matching parts and a logical plan


Staff member
I just had a rather long and detailed discussion with a guy who it was all too obvious ,was basically just,
trying to get me to give him a detailed list of engine components to build his engine.
one of the main secrets , too building a really effective combo is to match the engine and drive train components you use.
too the intended rpm range and power range.
like with most performance parts and applications the critical part of the build,
is generally in selecting the correct components for that particular application,
and in assembling those components correctly with the correct clearances.

its always a multi layered process,

you can,t expect sub-par or weak parts to withstand the shock and torque and rpm/impact loads.
you can,t also expect improperly installed or clearanced or insufficiently lubricated or cooled parts to last very long under loads.
obviously the process REQUIRES the person doing the work, or assembly to do some in depth research,
and have any tools or measuring devices that will be needed.

now thats hardly rare, and Ive had similar discussions a hundred times, Ive build a whole lot of engines and seen a whole lot more than those built and raced, and 95% of the time the guys building or racing those cars have made mistakes that were eventually corrected.
many guys ignore proven combos, because it may cost more than they want to spend, and either insist on using components they own currently or think they can buy far less expensively than the components, I know from experience will actually work.
it helps a great deal if you take the time and effort to find a trust worthy and reasonably priced local machine shop , and trust me when I say this is critical, and yes, the machinist will seem to point out endless things that should be done to increase durability, or just allow proper component function,and a good machinist will try to guide you in component selection to help avoid mis-matched parts and low quality parts being used, yes quality parts and machine work, ALWAYS COST more than you may expect them too!

but the thing that made me crazy during this discussion, was that Id ask specific questions, as to his goals, his budget, his skills and what he wanted to accomplish, and then suggest parts,, not necessarily a brand or a specific part number most of the time, but Id suggest something like find a deal on some cylinder heads that have about a 210cc port, 2.02 intake valves and flow in the 270-280cfm range at .600 lift and list detailed reasons why I thought those parts were a good match to reach his listed goal, and it was all too obvious that his real goal was to get me to suggest he use, or approve of or some how validate a huge list of totally miss matched, and mostly stock components, components that I strongly suspect he all ready owns, that were never going to allow him too reach his stated goals as to power and rpm range etc..
Cylinder Pressure Note: youll generally want to try hard to maximize the useable compression as the higher the compression before you get into detonation the more efficiently the fuel can be burnt and the more torque the engine can produce, if limited to pump high test 92-93 octane fuel,165 psi # of cylinder pressure is about the best cylinder pressure for Iron heads with 92-93 octane, using pure un-ethanol laced fuel, gasoline. while the faster heat transfer rate of aluminum cylinder heads will usually allow 190psi # as the upper limit or best for aluminum heads.
anyone can slap together parts and a few get lucky and find a combo that runs fairly well, but the chances wildly favor those guys that take the time to follow well known previously successful engine combos or at lease very similar builds

look, I,m probably never going to see this guy, Ill never make a single dime on his build and theres no possible reason Id want him to do anything but succeed with his build and be happy with the result, I don,t get anything, no financial kick backs or commissions, But I would like to see him reach his goals and not waste a ton of money and time building something thats doomed from the start to be restricting his potential power levels to far below his stated goals.
I started and maintain this web site mostly on my own dime with some very appreciated assistance occasionally, but its whole purpose is to help prevent the members from going thru the decades of frustration, wasted cash, mistakes and wasted effort I went thru and many (most) of my friends went thru before we learned some basic facts about what WILL and what WON,T generally work well when building a car, an engine or a garage and related subjects.
keep in mind your very unlikely to find a problem thats unique , or build something that someone else has not already built or at least built something very similar, so do some research, and follow previous successful car builds, look over those similar builds and be aware that knowing how the previous guys solved similar problems, can save you a great deal of time and effort, and if you want an engine that makes lets say 600 hp the best route is to duplicate a previous successful build that reached or exceeded that goal, not throwing together random components and hoping your combo will work.
heres some basics that won,t change theres a couple thousand related threads here to help you.
You may find this a bit different from other forums, as I can assure you I spend about 97% of my time on this site adding links info and valid additional text, where its needed in older threads as I see the need, I don,t think youll find many threads that are 6-8 months old or older that have not had additional sub links or pictures or text added
rebuilt or new chevy 383 crank






you need a decent , dry, level place to work, and at least some decent tools, you don,t need a huge garage, a 10' x10' shed or a single car garage, with a level concrete floor might do, but you do need a safe place to lock up and store tools and parts
a few hour or days of research can save you weeks of wasted effort, and having skilled friends helps so make as many contacts as you can in the hobby.
it helps to have friends that are willing to help.
find a decent quality machine shop you can trust.
parts and machine work always cost more than you think they will.
you need a plan with a well researched and detailed parts list.
youll need a decent engine stand and an engine crane if you do many engine builds.
lighter weight cars tend to be faster and easier to stop, and break fewer parts.
even a great engine matched to the wrong drive train or gear ratios will be well down on performance.
access too an air compressor , a drill press and a decent welder and a few accessories helps a great deal.
you NEED decent dependable transportation, and thats NOT going to be your performance car project.
any money you spend on parts that don,t match your well researched list , no matter what kind of a "DEAL" you get is likely to be wasted cash.
you will NEVER have the best or fastest car, unless bill gates is paying your bills,
but that certainly will not prevent you from having a really nice car., persistence and a well though thru plan are the key.
don,t get frustrated,everything you do is likely to take 2-5 times longer that you expect and cost more money, its part of the hobby, take the time to improve your skills, acquire parts and tools and make contacts in the hobby.
COMMENTS? THOUGHTS?USE THE CALCULATORS to match port size to intended rpm levels... but keep in mind valve lift and port flow limitations

the best bit of advice I can give , is if your in the process of assembling an engine,
or doing some mods to the car,
and you see ANYTHING that looks odd, out of place ,
makes you doubt you did something correctly ,
or you find something does not quite fit,
or you see something just not something you expected,
think things through.... but don't proceed until you know your 100% correct.

There is a reason why you are asking this question,
the just get a bigger hammer approach is surely the fastest way to get in serious trouble that will cost your a ton of cash and time wasted
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I love it, my best friend is one that just throws together mismatched parts and expects the moon. I have made that mistake with one engine in the last 4-5 yrs and won't do it again. I am planning a build right now and have a list but it seems to change daily. hahahahahaha!!! Thanks Grumpy, very good post friend!
By David Reher, Reher-Morrison Racing Engines
do yourself a favor.. buy this book

“Here’s a Reher analogy you’ve never read before: A racing engine is like a bowl of Jello.”

My daily fitness regimen is a brisk morning walk at Texas Raceway near my home in Kennedale, Texas. It’s just me, my dog, and a drag strip.

It’s quiet there on a weekday morning, and a man can think. Among things I’ve been thinking about recently are the common mistakes that racers make. One of the biggest errors is collecting parts for an engine that will be built “someday.”

Some racers build engines on the installment plan by stockpiling parts over a period of time. I know that a limited racing budget often dictates when parts can be purchased. However, the problem with this plan is that better parts are constantly being developed. Many components that were state-of-the-art a few years ago are now far behind the development curve. I think it’s a better strategy to collect the money to build an engine with current technology than to collect obsolete parts.

The pace of change in engine technology is accelerating. I see the evidence whenever I walk through our shop. Piston rings for sportsman engines rival the rings used in Pro Stock just a few years, at a fraction of the cost. Precision-machined dry-sump oil pumps that were once reserved for high-end engines can now be bought for a third of the price. Some sportsman cylinder heads can now outperform the extensively welded and modified castings that the pros used just a few years ago. And when I look at the valves and springs available now, I am amazed by the progress that’s been made in metallurgy.

It doesn’t take long for components to become obsolete. If you’d asked me two years ago about cylinder heads, rocker arms, and cam profiles, my recommendations today would almost certainly be different. My advice back then wasn’t wrong – it was simply based on what was available at the time. If you intend to race in the fast eliminators that have become popular with sportsman racers, then you can’t expect to be competitive with “antique” parts, even if they are only a few years old.

Another potential pitfall of buying parts piecemeal is ending up with an unworkable combination. Consider the staggering variety of big-block Chevrolet cylinder heads on the market – conventional ports, raised ports, spread ports, symmetrical ports, 18-degree heads, 14-degree heads, and many other variations. Each distinctive design requires specific complementary components, from intake manifolds and pistons to rocker arms, gaskets, and valve covers. Consequently that trick manifold introduced in 2010 may not work with the cylinder heads you buy next month.

It’s painful when a customer brings a pile of mismatched parts into our shop and asks me to build an engine out of them. I hate to turn business away, but I have a responsibility to be honest when someone shows up with a collection of incompatible parts. When a customer asks me to put a set of CNC-machined large-port cylinder heads on a marine engine that’s going to cruise at 3500 rpm, I really have to point out that he’d be much happier with smaller ports.

Here’s a Reher analogy you’ve never read before: A racing engine is like a bowl of Jello. Why? Because you can’t wiggle a bowl of Jello in just one place. Touch one part and the whole thing moves. To continue the metaphor, you can’t change just one part of a racing engine without affecting the entire combination. Change the intake manifold, and you may need to change the cam, the carburetor, and perhaps even the rearend gear ratio to get maximum performance with a new setup.

It’s easier than ever to purchase parts through online auction sites, virtual speed shops, and manufacturer websites. But are those parts in your shopping cart really the best for your application? Are they compatible? Are they high-quality components or cheap knock-offs? Before you hit the “Buy” button, it’s worthwhile talking with people who have real-world experience with building, testing, developing, and maintaining race engines.

Let’s say you buy pistons that are advertised as having a 14:1 compression ratio. And when you assemble the engine, you discover the actual ratio is 11:1 because the valve pockets and domes are designed to clear any conceivable cam/valve/cylinder head combination. A universal piston isn’t going to be effective and efficient in a serious racing engine. You don’t need or want .300-inch piston-to-valve clearance, but that may be what you get unless you talk with an expert.

There is no shortage of Internet experts who claim to have all the answers on engine building. Unfortunately, some keyboard gurus have little practical experience. I see endless discussions about rod length-to-stroke ratios on forums and bulletin boards, yet on the list of important factors in engine performance, rod ratio ranks about fiftieth. And please don’t get me started on cylinder head flow numbers. CFM is one of the least important characteristics of a competition cylinder head. Two head designs can have identical flow numbers, yet one will rev up and run on a racing engine, while the other is as flat as West Texas. In level of importance, the average air speed, port shape, and the efficiency characteristics of the port rank much higher than simple CFM numbers. Yet these vital characteristics are often overlooked, and most cylinder heads are sold on the basis of CFM figures.

Drag racing is a technology-driven sport that is continuously evolving. The winners constantly look for the next step forward, not yesterday’s hot setup.
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Verifying your engines clearances, and rocker geometry, and use of A rocker stud girdle and high quality roller rockers go a long way towards maintaining valve train durability



the higher rocker ratio increases the effective acceleration rate of the cams lobe ramp, being transmitted to the valve so the higher ratio tends to cause valve control issues at a lower rpm level UNLESS the valve spring load rates increased to compensate. this allows a greater area of lift or open port area so the engine will tend to run better in the mid rpm range, generally making it well worth while as the mile duration cam can use the extra lift and duration at the valve.

before you install any cylinder head on any engine clean it carefully , verify there's zero crud in the internal passages, and verify the clearance that you can, and first clean both the block deck and cylinder head mating surfaces with a clean lint free cloth soaked in acetone,
don,t even think of using copper paint its not designed as a true sealant in a similar application, use the correct sealant
I spent decades of time building engines using salvage yards as the source for the majority of the components ( I used, and recommended)
I also spent and still spend a great deal of time building engines for myself and others, with huge restrictions on component cost and time.
Brian may think I like to point out high dollar parts....
no I hate having to spend money, on parts especially if theres a perfectly good component you can get at a local salvage yard that will work perfectly well in the application,
that may cost less than 10%-40% of what the aftermarket part may cost.... but I think excellent long term durability is far more important than throwing something together fast and cheaply, that may not last very long If you do the research, and check everything the first time...if you , do things correctly and you don,t need too do it over.
I also built more than a few (several dozen 389,400,421, 428 Pontiac back in the 1960s-1990s, and several more in the last few decades
, or as the old saying goes.. if you can't afford to do it correctly, how are you going to afford to do it over when it self destructs after the original parts selected fail.

yeah it frustrating at times..

here is one area of reality, where the difference lies between the best vs the better ,
and the all too frequent .... guys charging an exorbitant amount of money for inferior work,

you know, exactly what I'm saying if youve ever dealt with skilled machine shops,
and the better mechanics, and all too often, scam machine shops, and fly by night operations, that pop up and go out of business every few years,
and why good machinist and knowledgeable engine builder's ,are so hard to locate, and most have long wait times , too get quality work done..
and why it almost always costs considerably more, and frequently takes longer to have some shops and race teams, work on your car or engine,
its also why many guys get rather pissed off, when they see what it costs for a top quality builder to build any engine.
and without doubt guys in some shops see what the best shops charge and think.. hell, if the best shop in my area, charges that much I should be charging a good deal more,
and I can knock that out for a bit less and in less time and make a killing...... and why finding a good machinist and machine shop is a real challenge in most areas.
I can easily suggest a cam , but its a rather meaningless gesture, and all too frequently a waste of time and effort for both of us.
simply because, without verifying the facts, and this is where Id say the vast majority of internet web sites,
and the recommendations, you see being posted in them, all too often, go wrong far too frequently.
yeah its easy to assume the timings correct the true functional compression, in every cylinder is nearly identical,
(most guys measure, two or three cylinders and without a second thought ignore the rest,
and thus they, blissfully assume all the other cylinders must be the same or so close its a waste of effort,
, most guys fail to put in the effort, too measure the less easily accessed cylinders, thinking
(why bother its a P.I.T.A. and if the first two or three are fine so will the rest of them, )
and that is the attitude that will be used for other factors, yeah, most guys, and every other guy reading similar threads on a vast ocean of similar web sites,
all over the internet, skip over anything that is redundant or takes a bit of extra effort, they simply assume they know things that may or may not be true.
the vast majority of guys , are absolutely convinced, that verifying every measurement and clearance issue in their engine,
in each cylinder is so close that they are effectively duplicate in all areas,
yeah without any doubt... its a waste of time and effort, too do what most guys, will just be convinced is busy work,
yes most tuners and car owners are just like the vast majority and are convinced everything between all the cylinders have not changed are exactly as you and they remember them too be..
especially if they have taken the time and effort too do things correctly several times in the past and found that to be true in the past.
thats the difference between the 5%-10% of guys consistently posting the best and most

consistent time slips and lap times vs the guys that frequently win a few races,
but over a season or two, don,t consistently, year after year build a good reputation, for durability and consistently winning.

be aware of the quality of the components you select, there are several merchants that advertise a great deal based on lower prices, who generally deal in the lower and mid range quality products,
and its goal seems to be a low price volume discount supply house.
now Ive seen a few good deals, over the years but keep in mind,
youll generally find discount price parts, use lower quality components or,
less extensive precision machine work, or imported components or a combination of those factors to reduce price.
now I'm not picking on the lower price parts suppliers, they certainly have a place in the economy and hobby.
I use rockauto and advanced auto, walmart and several other suppliers,
if I need too ,but I generally know the parts and use name brands not cheaper import clones.
remember thats frequently a very noticeable difference in quality, in similar components,
you may pay more for name brand parts and at times the higher cost is not justified in my opinion,
but many of the better known brands do tend to have better quality control and R&D
I would suggest you do research and avoid using the lowest cost import parts like bearings, brakes, and suspension parts ,
as Ive seen horrendous quality control on some import component examples
DO yourself a huge favor and carefully read the threads and sub links.. below
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the first few rule's of GRUMPY'S engine assembly







(2) if in doubt, about how to do anything, on an engine, do some detailed research,
find and compare at least 3-5 valid trust worthy sources info,
read the instructions over again, several time's very carefully
and if available watch several related videos.

(3) if any component will not easily function as designed or requires a good bit of physical force to install ,
or your not 100% sure your doing something CORRECTLY

theres a reason, and you better verify your clearances are correct , and your following the instructions before you proceed.

(4) never assume the parts you purchased can be used without carefully , cleaning them prior too,
checking the physical condition, verifying clearances and using the correct sealant, lubricants etc.

(5) the quality of a component is generally at least loosely related to the cost to produce it,
and the amount of detailed research and quality machine work that went into its production.
if you got a significant reduced price, theres typically a reason.
it might simply be because a new improved part superseded the one you purchased,
but it might be a far lower quality imported clone with lower quality materials and machine work.
its the purchasers responsibility to research quality.

(6) if you did not do the work personally or at least take the effort to verify it was done correctly and personally verify clearances

ITS almost a sure thing that it was NOT done , correctly, and yes that mandates you fully understand what your looking at,
and how the components are supposed to function and have high quality precision measuring tools.



blueprint engine blocks


world products blocks

G.M. performance








When the Mark IV was installed in production vehicles for the first time in 1965, it carried the Turbo-Jet name on the air cleaner, displaced 396 cubic inches, and was rated at a maximum of 425 horsepower in the Corvettes.

Here’s a quick look at milestones in the big-block’s expanding and contracting history of displacement:

396 cid – introduced in 1965, with 4.094-in. x 3.760-in. bore and stroke (first production Mark IV engine).

427 cid – introduced in 1966, with 4.250-in. x 3.760-in. bore and stroke (aluminum versions used in COPO supercars).

366 cid – introduced in 1968, with 3.935-in. x 3.760-in. bore and stroke (tall-deck; used in truck applications).

402 cid – introduced in 1970, with 4.125-in. x 3.760-in. bore and stroke (advertised as 396 cid).

454 cid – introduced in 1970, with 4.250-in. x 4.000-in. bore and stroke.

502 cid – introduced in 1988, with 4.466-in. x 4.000-in. bore and stroke (Gen V block, originally developed for non-automotive applications; adapted later by Chevrolet Performance).

572 cid – introduced in 2003, with 4.560-in. x 4.375-in. bore and stroke (developed by Chevrolet Performance; no production vehicle applications).

the longer exhaust duration and wide LSA is an advantage if the exhaust is provides more time for the mass of exhaust gases to exit the cylinders,keep in mind its that properly timed exhaust that drags in the following intake charge.
if your using open long tube headers with the proper length primary and collector design,to match your displacement ,compression ratio, and cam timing, longer exhaust duration rarely provides a useful advantage.






read through these links, and sub links,
yes it may take a couple days,
but after understanding how and why things work,
the info is sure to save you a great deal of wasted time,
and a bunch of wasted money.

there's a bit of discussion on cam selection in the thread links posted above and in this thread, notice the cam selected is far from the most radical that might fit the application,and there's discussion on the differential gearing intake selection and trans gearing and converter stall speed, and while the cam and heads selected were not (BY DESIGN) the components that would cost the least or produce the best peak power numbers they ARE well matched and can quite easily do two things, provide dependable and instantly available and impressive torque, and allow the car to drive without problems on the street, something, in the cars drive-able characteristics, that a much more aggressive cam, that makes a bit more peak power would most likely not provide.
this is a factor that a great many people don,t grasp or understand, and thats correctly matching the combos characteristics to the true intended application, it makes no sense to build a 600 hp sbc that produces peak power at 6700 rpm if your car has a transmission and gearing that restrict its operation to the 1500 rpm-6300 rpm range, yet I constantly see guys read the magazine articles in places like stock car magazine and decide to try and duplicate some 600 hp plus combo they read about on a street car engine build, then they proceed to really screw it up further because they decide that the expensive cylinder heads and block machine work can be ignored to save money, so they substitute much less expensive components and don,t match the drive train and gearing and act stunned and amazed when the combo of mis-matched components runs like crap, gets into detonation issues and surges and bucks at anything under 4500 rpm.

BTW, if your 496 -540 displacement BBC combo includes an engine with at least 10:1 compression and a cam with at least 240 duration at .050 lift, and oval port heads, youll almost always find a single plane intake has some advantages over a dual plane intake.

link too bore vs stroke info on hundreds of engines ,
Id point out one very common mistake I see made is guys ignoring the addition of a 7-8 quart baffled oil pan,

and ideally a windage screen,as this has a very noticeable effect on increased engine durability

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Im always amazed frankly at guys that insist they need a certain cylinder head port CC size for an engine, especially when I doubt theres been much if any time spent actually doing the required calculations required to find the correct cross sectional area of an engines intake port or manifold runner length, and you can,t possibly do that required math with out matching the engines displacement, compression ratio, intended power band,rear gear ratio, tire size,cam timing (lift & duration) valve curtain size, after measuring the cylinder head port cross sectional area, and header primary size and length.
I see guys have long discussions about things like the difference in port cross sectional area or the best connecting rod length, to use, no one factor is going to make your engine totally dominate the competition, its a combo of small almost insignificant individual component choices being made and a good deal of time and effort taken during the assembly and clearancing work, that stack up to give you or prevent you from maximizing the engines performance.
you may not even think about factors like polishing crank journals, or valve train geometry or intake runner cross sectioinal area or length ,or intake runner port matching or surface finish, but the combined effects of your choices and components selected do mater!
look guys I think a good deal of this discussion is missing the point here, Ive built well over 150 engines in the last 45 years, (I lost cound decades ago)
but I can assure you that longer rods and the easily verifyable slight increase in dwell time, the longer rods produce will be totally meaningless UNLESS, you design the engine for and select components too take full advantage of the minor increase, by carefully calculating the REQUIRED compression ratio,fuel octane required,all the factors related to the cam timing,(duration,lift, LCA) you calculate and build and install, and tune the engine for , a matched exhaust header scavenging (header primairy length and diameter plus collector design) and the intake runner length and cross sectional area, to maximize the cylinder scavenging effects, plus you match the fuel/air ratio, and ignition advance curve, to maximize that longer dwell times potential advantage.

I often have guys state they NEED a 180cc or 170CC port head to maintain low speed torque, then the same guys insist they need a VIC JR single plane intake and a 750 cfm holley double pumper carb, (for better peak power) and they will also point out the need for RAMS HORN EXHAUST MANIFOLDS to maintain good flow but save the cost of headers..obviously the list of mis-matched parts selected could be endless, the main point is that guys read some magazine article , and assume the limited info they read, is valid! (and not knowing that most of the stuff not being mentioned, and purposely over looked is critical) like the fact the car has a 4.11:1 rear gear and a 3200 rpm stall converter, ported heads, and extensive tuning, a non-stock ignition, and other mods.. and then they mistakenly assume the little info they do see, relates to every possible combo.
guys come away from reading the magazine articles, thinking all, thats required to built a killer engine, is slapping a listed cam and vortec heads with some trick intake manifold on a low compression 350 sbc to run killer times and do endless burn-outs

the very mention of the fact that theres MATH formulas available to actually calculate the correct matched components has never once been mentioned, and when it is I get that deer in the head lights stare or Im ignored as an OBVIOUS JERK who is just out to piss on their pizza , as they have read through several magazine articles so they know exactly whats needed!
selecting the CORRECT MATCHING CYLINDER HEADS is not a randomly made choice if your doing it correctly, its a process of matching the needs of the engines requirements under known or at least expected conditions.
yes its a KNOWN process with well understood MATH and REQUIRED testing, if your not following a know recipe exactly.

mention the fact theres actual tests for ideal fuel /air ratio, exhaust back pressure in the exhaust system,and intake plenum vacuum , fuel distribution, bearing surface speeds, rpm limitations , and ignition timing , valve float, air flow rates in the intake ports , port stall and they look at you like you are 9 feet tall and just stepped of a flying saucer

While cheat sheets might have frowned upon in your sixth-grade classroom, we strongly encourage them in the garage, shop, or pits. That’s why we’ve put together this list of 13 key performance formulas you should know when building or tuning your street or race vehicle. dynamic Comp Ratio.htm

Racing Carburetor CFM
Racing Carburetor CFM = RPM x Displacement ÷ 3456 x 1.1
Note: Summit Racing also offers this CFM Calculator to make the job easier.

Displacement = .7854 x Bore2 x Stroke x Number of Cylinders

Correct Compression Ratio (CCR)
CCR = FCR (Altitude/1,000) x .2
Note: You can also take this Compression Ratio Calculator tool for a spin.

Tire Diameter
Tire Diameter = (MPH x Gear Ratio x 336) ÷ RPM

Rocker Arm Ratio and Valve Lift
Gross Valve Lift = Camshaft Lobe Lift x Rocker Arm Ratio

Horsepower = (RPM x Torque) ÷ 5,252

Torque = (5,252 x HP) ÷ RPM

Rod Ratio
Rod Ratio = Rod Length ÷ Crank Stroke Length

Average Piston Speed
Average Piston Speed = Crank Stroke x RPM ÷ 6

Rear Gear Ratio
Rear Gear Ratio = (RPM at Finish Line x Tire Diameter) ÷ (MPH x 336)
Note: You can also save this link to a handy Gear Ratio calculator.

Volume (CCs) of Deck Clearance
CCs of Deck Clearance = Bore x Bore x 12.87 x Depth of Deck Clearance

Volume (CCs) of Head Gasket
CCs of Head Gasket = Bore x Bore x 12.87 x Thickness of Head Gasket
felpro # 1204=Port Size: 1.23" x 1.99"=2.448 sq inches

felpro # 1205=Port Size: 1.28" x 2.09"=2.67 sq inches

felpro # 1206=Port Size: 1.34" x 2.21"=2.96 sq inches

felpro # 1207=Port Size: 1.38" x 2.28"=3.146 sq inches

felpro # 1209=Port Size: 1.38" x 2.38"=3.28 sq inches

felpro # 1255 VORTEC=Port Size: 1.08" x 2.16"-2.33 sq inches

felpro # 1263=Port Size: 1.31" x 2.02"=2.65 sq inches

felpro # 1266=Port Size: 1.34" x 2.21"=2.96 sq inches

felpro # 1284 LT1=Port Size: 1.25 x 2.04''=2.55 sq inches

felpro # 1289 FASTBURN=Port Size: 1.30" x 2.31" 3.00 sq inches

blueprint engine blocks


world products blocks

G.M. performance

heres a chart FROM THE BOOK,HOW TO BUILD BIG-INCH CHEVY SMALL BLOCKS with some common cross sectional port sizes
(measured at the smallest part of the ports)
...........................sq inches........port cc
edelbrock performer rpm ....1.43.............170
afr 180.....................1.93.............180
afr 195.....................1.98.............195
afr 210.....................2.05.............210
dart pro 200................2.06.............200
dart pro 215................2.14.............215
brodix track 1 .............2.30.............221
dart pro 1 230..............2.40.............230
edelbrock 23 high port .....2.53.............238
edelbrock 18 deg............2.71.............266
tfs 18 deg..................2.80.............250


you may be amazed to find a great deal of research and testing has been done and theres actually proven facts rather than random guess work to use in planing a well built engine combo



reading a few links and sub links is well worth the time and effort



why is it that darn near everyone just reads a few magazine articles and assumes that when they show remarkable gains from a cam swap that they don,t mentally step back and ask what to me is an obvious question, "WHAT DID YOU DO THAT YOU FAILED TO MENTION?" like new valve springs ,new rockers, larger injectors porting etc. look the fact is that most stock valve trains are not designed to run at over 6000rpm, and most cars have injectors sized for the original power level, and most cars have automatic transmissions and rear gear ratios , and compression ratios more designed to lower emissions and increase mileage than to maximize peak power, so swapping a new more aggressive cam MANDATES other changes, like long tube low restriction headers and a low restriction exhaust behind the headers, to allow it to function to its full potential, and additions like an additional trans fluid cooler to math the higher heat produced by a higher stall speed torque converter and a different rear gear ratio, and better valve springs, higher cost roller rockers and porting the heads and intake is conveniently ignored,and that the original stock parts won,t work well with the new performance cam, without the parts they forgot to mention when that miracle cam jumped the peak power 80 plus hp is simply ignored, as posting that info might reduce sales of the cam the articles pushing for sale are not compatible with a noticeably longer duration cam. its the combo of small improvements and intelligently selected matched components that adds up, to allow you to build an impressive engine.
choices like upgrading from the stock rocker arms on an Lt1/Lt4 to a set of quality aftermarket full roller rockers with a 1.6:1 ratio might only produce small gains by themselves but
keep in mind that on an LT1/LT4 engine, in a corvette, that had about a 330-350 hp rating, the rockers having a gain of 12hp-17hp like I mentioned is about a 4%-5% boost, while its not going to pin you back in the seat during acceleration it might put you an extra 8-10 feet ahead in a 1/4 mile drag race as you go through the lights compared to the old combo

spending a few days or even weeks doing careful research well before you start writing checks or pulling out a credit card, can save you thousands of dollars and months of work, understanding the difference in component quality ,correct clearances and how and why each component is supposed to perform and the potential stress its under helps you make far more intellegent choices and tends to allow you to get an engine built that far exceeds the quality and performance of the average crate engine assembly

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I Really enjoy Reading your Personal Ancidotes Grumpy.

Big Blocks for me.
1 Street Engine.

The other Race Engine.
they purposely
little things like having to spend 45 hours porting the heads and intake,or clearance milling the block, or welding on the oil pan,to get them functioning correctly, or having to junk the original valves and valve springs and retainers to get the proper geometry, just get ignored
and concentrate on promoting this month favored part vendors product
most engine builds are at best thinly disguised advertisements for some vendor, or LIST OF VENDORS components
notice the list of manufacturers commonly listed in the article

youll rarely if ever see any detailed description of the valve train components
what the exact valve train clearances were the type of valves used the multi angle valve jobs
the back cuts on valves
what the part number was on the valves, or keepers, retainer, valve springs, shims cups clearances.

Once in a while Grumpy will talk about 7 K rpms.
Not very often.
thats simply because, of experience!
lets assume you have a 1969 camaro , that looks great like this

with several aluminum or fiberglass components and get the weight down near 3200 lbs with you in the car!
I learned decades ago that you can have choices and choices have concequences,spin a small efficient , high compression (12.5:1) engine , like a 302 sbc with a carefully assembled solid lifter valve train to 7500-8000 rpm
and make lets say 1.5 hp per cubic inch (302 x 1.5-or 1.6:1 = about 450 hp- maybe even 480 hp) and use expensive race octane fuel, which gets constantly more expensive and limits what you can do and where you can go with the car,
or you can build a 496 BBC,
now lets say you build it to have 10.5:1 compression so you can run it on premium pump 95 octane(hard but not impossible to find, especially if you are willing to add some octane booster occasionally.
4200 fpm with a 302 and its 3" stroke = 8400 rpm
lets say you cam that 302 so your making 350 ft lbs at 7000-rpm. thats 466 hp
or you build the 496 and make lets say 1.3 hp per cubic inch, and 1.3 ft lbs per cubic inch of displacement and with its 4.25" stroke the same 4200 fpm, limits you to, about 6000 rpm.
the 496 BBC makes nearly 645 hp and 645 ft lbs, and while it weights about 100 lbs more and might cost an additional $1000-$2000 additional to build
(remember the small blocks going to require an expensive valve train and decent forged components just like the BBC if you want both engines to last long term)
lets say we go with a 4 speed muncie in the 302 and match it to a 12 bolt with 4.56:1 rear gears
on the BBC we instal a 4l80R and a dana 60 so between the transmission, 3.55:1 rear differential and engine the BBC 496 car easily weights an aditional 330 lbs

your killer sbc in the 3200 lb camaro with its 466 flywheel hp is maybe at 400 rear wheel hp, that equates to about....Your ET / MPH computed from your vehicle weight of 3200 pounds and HP of 400 is running near, 11.65 seconds and MPH of 116.01 MPH.

your much more street friendly 496 cubic inch pump gas BBC 3530 lb camaro has about 540 rear wheel hp
Your ET / MPH computed from your vehicle weight of 3530 pounds and HP of 540 is running 10.89 seconds and MPH of 124.09 MPH.
or close to a second faster, its much easier to drive and you can actually go on trips because if your careful pump gas can be used.
think about the difference here, one car sounds impressive like a chain saw running nitro methane, its damn impressive running mid 11 second times at near 116 mph in the 1/4 mile but you don,t get to drive it much on the street because race octane fuel cost over $4 a gallon, and it runs like crap under 3500rpm

on the other hand the BBC version runs pump high test (maybe a bit of octane booster) and costs you maybe an additional $3-$4 k to build but its damn near bullet proof and you can jump in and drive from Colorado to Miami if you wanted to with a more reasonable expectation of arriving without having had and issues.
(keep in mind with 28" rear tires
the manual muncie sbc car spins roughly 3800 rpm at 70 mph.
the BBC version with the OD trans and the same tires is spinning about 2300 rpm on the same trip at 70 mph

There are places money can be saved and places it can't be some parts really make the combo what it should be. There are reasons why guys fall short on their goals of what an engine should be putting out. It usually has to do with a variation or compromise in the proven formula.

yeah! thats one extremely common reason why guys fail to build a decent engine,
I can,t begin to list the number of times I've had some guy ask me to build him an engine ,that will make 500,or 600 hp, for his muscle car, and when I explain whats involved in time and money to do it correctly,
and propose a very detailed list of the required machine work and draw up a parts list,of a well tested , known combo, I've built, before
without any doubt the first thing out of their mouths is the fact they want to substitute 1/2 of the parts for less expensive components,
and skip 3/4's of the machine work and then use a few parts they already own
they invariably are convinced that cheaper similar parts will work out fine and cost less!

When I explain that we can follow their version but it won,t make anywhere near the same power,
they generally can,t or won,t believe me.... at first!

I generally say, look this is a bit like backing a cake, if the recipe, calls for 2 cups of cane sugar and that sugar costs $4, and you go to the local store and find you can buy SALT that looks identical, for 79 cents, you could use that and save almost 80% on the cost!
both items are white granular substances, they look almost identical,, both are commonly used and there,s not a damn thing wrong with either product,
but I can assure you the resulting "
cake"or ENGINE, built using the less expensive substitute product will result in a much different finished result.
then I point out that THEY will be buying the parts and paying the local machine shop bills for the things I don,t have the required , tools to complete, and I'm probably not going to make over $5 an hour for the week or mores time that the project will require.
they have a choice, they can go to almost any local machine shop or buy a crate engine and in either case spend less money, but they are also not going to get the same end result.
you can take your time, take advantage of decades of experience, and learn how and why things get done a certain way ,and measure and carefully clearance and fit components and do things correctly
you can buy and assemble any random list of parts, or buy a crate engine, in either case your car will probably be up and running in a few weeks,
if you want things done correctly you,ll spend a good deal more time and probably 60%-to 200% more money , but I will not be making squat on the deal,but I will get a good deal of satisfaction from the end result.
yes I enjoy the builds and enjoy teaching, and yes I love watching guys, who correctly built their engines, blow the doors off the guys who go the crate engine route , or slap together random components.....this is not and never has been a money making proposition, and I don,t work too a stop watch....if it takes longer and costs a good deal more thats the price of quality, ..but I do have a decent list of satisfied people who like the results they got from building their engine with a good bit of help, many have returned several times over the decades, and I sleep well knowing they did the job correctly.
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the very mention of the fact that theres MATH formulas available to actually calculate
Yeah. That's funny. When is the last time you saw anyone that could actually make change for a dollar without the cash register telling them?
If we lost power long term today, within a week 1/3 of the population would be DEAD.
Yeah. That's funny. When is the last time you saw anyone that could actually make change for a dollar without the cash register telling them?
If we lost power long term today, within a week 1/3 of the population would be DEAD.
LOL Mike.
I was recently over at a friends home where he showed me a back un-used bedroom,
it was partly filled with a stack of boxes from summit, jegs etc.
and he had a legal pad with a good percentage of the parts he wanted to use,
listed and checked off,and it was obvious he had put a good deal of thought and money already into his dream car.
I think most of us have run into a great many similar choices, between buying tools and auto parts,
its simply the result of a limited budget ,in most cases,
and most of us make a few mistakes ,
but as long as you keep the goal of building the car in mind you'll do ok.
after you gain experience there's both engineering and art involved in the process,
you'll generally start with a goal, you've envisioned for your car, reality and physics will provide some of the limitations, you'll be limited to a budget and at times by your access too tools and limited by your skills and knowledge, youll generally start,by simply making a very detailed list of the components you want too use ,to upgrade and modify the car to gain the performance and look of the car, and once you have that list of components, and being forced by going back through that detailed, list and doing the required math too verify you have selected the correct matching parts, and when you find you have to change a few components you go back, change the list and again revue the math, most of us start out without the required knowledge to accurately match parts and your goal.
yet this process forces you to do some research into what you can reasonably accomplish with the tools and skills you have and the realization that you may need to acquire both skills and more tools as you proceed.
He had that legal pad, where he had listed the exact components he had decided he needed to build,his dream car and its engine and drive train.
I looked over the list and if he ever gets it completed and assembled he will have one kick-butt car & engine combo.
I had to admire his determination, as his intention is to build a 540 cubic inch, centrifugally super charged, and intercooled,
and fuel injected, big block chevy engine that should easily put 800hp to the rear wheels.
he wants to put a 4l80e transmission and dana 60 rear differential in a 1969 camaro
I'm fairly sure many of the guys reading through this don,t or have not dealt with, or built enough engines, and been involved with enough of the engine builds to realize the various manufacturers approach building components with a great many different objectives in mind,
component parts vary and careful research and selection is required!
I've always found SCAT and CROWER parts seem to be a good value!
keep in mind the "weakest link in the chain" concept,
Any logical engine builder needs to sellect components with a firm goal in mind and recognize the intended power band and rpm limitations.
need there's not much sense in selecting a rotating assembly that is built to easily handle lets say 1200 hp and 7800 rpm, at 4500 fpm in piston speeds,
if the block main caps walk at much lower stress levels, or if the block your thinking of using it in,will most likely have the caps walk well below that stress level.
nore would it make sense, using such a high dollar rotating assembly if your going to match it with a valve train and hydraulic roller cam that floats valves at 6400 rpm, or heads that reach port stall at 6700 rpm
have you ever taken the time, and effort,
too step back and grab a legal pad and pen, and logically make a reasonably complete list of the parts you,ll need,
and do the research required too list every part, (including all the small components like bolts, bearings gaskets) and their current cost, where you can find those components for sale, and part number, brand and supplier, and the phone numbers etc.
and call a local machine shop to get a better idea as to the labor cost of a project your looking into starting?
once you do theres commonly three things youll face,
the first is generally a sense of being over whelmed and depressed at the un-expected,total projected cost!
the second is a very common and strong temptation to either scrap the whole idea or to start substituting cheaper and generally considerably lower quality components that in the long run will eventually make the completed project either not worth owning and certainly something your less than proud to own.
and the third is the strong tendency to purchase parts that you find for bargain priced that either are not well matched to the intended projects goals, or nearly useless when matched to the project goals, but the bargain price seems nearly impossible to pass on.

all these tendency's result in a great many partly complete or abandoned projects, or projects that don,t resemble anything close to the original intent, or projects that never get started in the first place.
the completion of a well designed project will take some detailed planing and the ability to stick with the original projects part list and goals, and doing your research in detail, as to both the parts and machine shop costs, the time required and in many cases the tools that you might need,and of course youll need a place to work and store the project while its being built or repaired, well before you start buying components
my dad always stated..

"A couple hours , well spent in doing carefully documented &,detailed research,
before.... jumping head first off the dock,
into any project,....can prevent you from wasting month's of non-productive work and a wheel barrow full of cash!!"

I was impressed that he had taken the effort to select matched components like
AFR 315cc heads


holley throttle body

holley 83 lb injectors

3200 rpm stall converter

crane hydraulic roller cam


crane roller rockers

dart block
  • Siamesed Extra-Thick Cylinder Walls: Resists cracking and improves ring seal (minimum .300'' thick with 4.625'' bore).
  • Scalloped Outer Water Jacket Walls: Improves coolant flow around the cylinder barrels to equalize temperatures.
  • Four-Bolt Main Bearing Caps: In steel or ductile iron have splayed outer bolts for extra strength.
  • Crankshaft Tunnel: Has clearance for a 4.500'' stroke crank with steel rods without grinding.
  • True ''Priority Main'' Oil System: Lubricates the main bearings before the lifters.
  • Oil Filter Pad: Drilled and tapped for an external oil pump.
  • Rear Four-Bolt Cap: Uses standard oil pump and two-piece seal - no adapter required!
  • Lifter Valley Head Stud Bosses: Prevent blown head gaskets between head bolts.
  • External Block Machining: Reduces weight without sacrificing strength.
  • Simplified Install : Fuel pump boss, clutch linkage mounts and side & front motor mounts simplfy installation on any chassis.
  • Dual Oil Pan Bolt Patterns: Fits standard and notched oil pans.
  • Bellhousing Flange and Rear Main Bearing: Reinforced with ribs to resist cracks.
  • Note: Does not include cam bearings, freeze plugs, or dowels
rotating assembly
It really pays to step back and make a list of your basic goals, your skills, and to think through where your going to work on any project you start and think through what you want to have once its built, and realistically think about your budget, and the time it will take, and realize any budget you write out at the start of any muscle car restoration project,is likely to realistically be about 1/3 to 1/2 of the real price,by the time your finished and it runs correctly, you'll have a good grasp on the hobby.
a good many guys start a project without listed goals, It helps to join a local car club to make contacts in this hobby so you can gain skills and get discounts on parts, and having several friends who are building similar cars rarely hurts either.
and if you really don,t know what you want too be driving in a few years you can spend amazing amounts of cash on parts you really can,t use and waste a great deal of time on a car that your never going to be happy driving.
but if you stop and think things through carefully and list the type of car, its engine and drive train, your favorite color, the type of interior, and other, characteristics, and then make a detailed list of the components and tools you,ll need and the skills you might need to acquire to build it, your much more likely to accomplish your goals and be happy with the results.
this whole forum.. is installed and maintained to make it easy for both the beginners and the very experienced hot rodders to find, or post information regarding various car and engine related subjects, youll find threads generally have links to related info,
no your not having anything extraordinary happen,
if your building your first engine and running into quite a few problems ,
with the assembly process or sloppy machine shop work!
slapping something together vs
are vastly different concepts
I look back on the first few engines I built when I was about 17,
and I'm amazed they even ran.
I had never heard of ring gaps,
yet in-spite of that the cars engine started and ran.
A great deal of the content in this whole web sites based
on the idea that readers can benefit from reading about how too ,
avoiding the expensive mistakes many of us older geezers made in the past,
and learning how things should have been done correctly
theres no possible way that I can know each particular problems cause, or suggest the best possible parts choice, or process to fix it, in every case ,unless you post detailed info and perhaps clear pictures. so I try to make it far easier to find answers to the more common problems and questions.
I try to give a good over view on how things work, how they can be tested and what commonly fails.
or I try to provide links to related sources to make your search for information related to any subject covered both easy to find and as extensive as you care to push into your research. I've been building engines and racing for 45 plus years and while I have done many things.
I've built well over a 170 plus engines in 55 plus years , but keep in mind thats only 2-4 engines a year most years, Im always learning and looking to learn from others in this hobby ,so if you can add useful links or information or just as questions to clarify an answer or question you read on the site,to clear up a question or find an answer too the info please do so.

this hobby's never been cheap and easy good parts cost money, and it requires you to gain skills, and ask questions
having lots of connections, a few friends and a place to work and a reasonable budget helps.
keep in mind parts listed in videos may no longer be available, companies constantly go out of business

any time your thinking of getting involved in something like a serious race engine build its a good idea (really mandatory) that you get out a legal pad, and pencils and start making phone calls to ask questions about all the little parts, tat add up rapidly like bearings and gaskets, asking about the machine work and your options and the cost and time required and if the parts are even available, doing your research, listing the cost, adding all the costs up, scheduling the time frame and vendors phone numbers, the names of the people you talk tom and asking if, the parts ARE in fact available, the cost and knowing ahead of time what machine work is required is a huge help to avoiding being in a bottom less money pit and not having a reasonable way out!
yeah! most magazine articles and short u-tube videos, make it look like anyone can assemble a 500-700 hp engine in a day or two, using off the shelf parts, and yeah, it looks like re- building that $4000 set of heads you found at a swap meet, that you remember seeing listed for $8000, is child's play
then reality hits and you find out why you were able to get that GOOD DEAL, on that guys abandoned project car and its parts.
yes there's bargains to be had, there's also a great many car projects that turned into bottomless money pits
keep in mind there's very few skilled machinists, that give a damn, and get projects out on the date they said they will,
and a whole lot of semi skilled machine shop personnel , willing to charge top dollar for low quality work, that they may get around too eventually,
and there's endless videos making it seem like you can build a truly impressive car, in your garage, without expensive tools and with only off the shelf parts for a 1/4 of what you thought it would cost... but the truth is you tend to get what you pay for and everything' tends to take 3-4 times longer than you expected it too.

loosely related threads

each area has machine shops with different tools, experience and unfortunately some machinists have attitude issues
and don,t seem to think delivering top quality work at reasonable prices and on promised delivery dates are a reasonable expectation.

related threads

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I recently got an e-mail telling me they really appreciated the advice I had previously given them on a BBC engine project,
but I had made a point out of suggesting they print out a detailed list of the parts and machine work they needed to accomplish the goal they set,
and now for some strange reason , every time they get a few hundred dollars saved they look at the list, and have an obsessive urge,
to buy some minor component that they can currently afford so they can cross it off the list of components,
they know they need, but because of that, purchase they seem to always be depressed that they never seem to save up the money to purchase the major components,
like blocks or rotating assemblies or cylinder heads.and looking at shelves full of dozens of components they know they need to build their planed dream car combo, is getting very depressing!
I fully realize all too well that this hobby is rather expensive and it also takes a good deal of time and effort to learn the skills and afford the parts for most of us.
one of the major reasons I started this web site was to help readers on this site avoid making expensive mistakes ,and too learn those skills, thus reducing the time and expense required.

learning from mistakes , and successes other people have made helps reduce your potential cost and effort.
it helps a great deal if you take the time and effort to find a trust worthy and reasonably priced local machine shop , and trust me when I say this is critical, and yes, the machinist will seem to point out endless things that should be done to increase durability, or just allow proper component function,and a good machinist will try to guide you in component selection to help avoid mis-matched parts and low quality parts being used, yes quality parts and machine work, ALWAYS COST more than you may expect them too!

yes logically they could save up and spend the cask on the major components like the blocks or rotating assemblies or cylinder heads, but inevitably, if they wait that long some family emergency developed and the cash reserve,
they had planed to spend gets spent else ware?
I simply stated that is an all to common in fact expected result in this hobby and many guys go and use the credit card option and as a result they get themselfs into financial issues !
theres simply no free lunch in life and the best option Ive found is to get side jobs and use that cash toward the project goal rather than the basic household budget.
have any of you gentlemen found better options in the course of financing your projects?
this whole forum.. is installed and maintained to make it easy for both the beginners and the very experienced hot rodders to find, or post information regarding various car and engine related subjects, youll find threads generally have links to related info,
no your not having anything extraordinary happen,
if your building your first engine and running into quite a few problems ,
with the assembly process or sloppy machine shop work!
slapping something together vs
are vastly different concepts
I look back on the first few engines I built when I was about 17,
and I'm amazed they even ran.
I had never heard of ring gaps,
yet in-spite of that the cars engine started and ran.
A great deal of the content in this whole web sites based
on the idea that readers can benefit from reading about how too ,
avoiding the expensive mistakes many of us older geezers made in the past,
and learning how things should have been done correctly
theres no possible way that I can know each particular problems cause, or suggest the best possible parts choice, or process to fix it, in every case ,unless you post detailed info and perhaps clear pictures. so I try to make it far easier to find answers to the more common problems and questions.
I try to give a good over view on how things work, how they can be tested and what commonly fails.
or I try to provide links to related sources to make your search for information related to any subject covered both easy to find and as extensive as you care to push into your research. I've been building engines and racing for 45 plus years and while I have done many things.
I've built well over a 170 plus engines in 45 plus years , but keep in mind thats only 2-4 engines a year most years, Im always learning and looking to learn from others in this hobby ,so if you can add useful links or information or just as questions to clarify an answer or question you read on the site,to clear up a question or find an answer too the info please do so.

Its up to the guy who assembles or builds an engine to verify that the machine work on any components been done correctly,
theres unfortunately a good percentage of machine shops that don,t employ people that have the skills and experience,
or the tooling to do the work correctly, or in some cases and desire or capacity to accurately measure the components accurately,
before and after precision machine works been done.
I'd bet 90% plus of the people who have a machine shop do precision work on any major engine component, like that
would have naturally assumed that the precision machine work was done correctly,
and simply assembled the engine without thinking a second about that work being done correctly.
this is one reason I strongly suggest most serious engine builders may want to have some precision,measuring tools,
and spend the time and effort to check that machine shop work you paid good money for, was in fact, done correctly ,

taking the time too verify the precision machine work was done correctly,
takes a good deal of the time required, in any engine build
(vs slapping parts together out of the box and wondering why it never quite runs up to your expectations)
and yes you probably could use the block in its current condition and find the engine runs,
and most people would never know the engines measurements were not correct or why the engine did not produce power to its full potential,
and the results might be so close that it would hardly matter ,too most car/engine owners.
but that engine block machine work ,being off specs, does not mean its been built correctly either
I have to point out I have 50 plus years devoted to gaining knowledge ,
about how you succeed at building reliable engines,and I pay a great deal of attention to the successful combos ,
and I've taken the effort too learn why the less successful combos failed.
now the truth is Ive made more than my full share of mistakes, but unlike most people,
I learn from my mistakes and the mistakes made by others and don,t generally repeat them.
I also take the time and effort to find out why parts fail, or why various mis-matched components don,t work well.
that seems to be a rather unique skill, from what I've seen.
if you take the time and effort required to read enough threads and linked info you'll see a pattern emerge!
its based on a concept that its far better to sacrifice a few peak potential horse power if thats required,
if that change can make a very noticeable improvement in the engines long term durability!
or as SMOKEY YUNICK used to say, the most important characteristic in building a race winning combo,
is simply that the most successful engine combo is based on an engine that has to finish the race in good running condition.
that in no way should be read as I can,t build a kick-butt engine with massive power, it just means that rock solid durability ,
takes presidence over adding a few additional peak, bragging hp, and a wide torque curve in the intended rpm range ,
adequate lubrication, cooling and staying out of detonation, and proper exhaust scavenging and a stable valve train,
are factors that take a far higher level of concern than bragging rights on a dyno.
or put differently, do it correct the first time, use the best parts you can afford , check your clearances, mandate 100% durability,
and strive for max torque in the intended rpm range, and let the hp numbers fall where they may!
Ive build almost 200 engines now over the last 50 years, and I can,t remember anyone having one fail unless they did something stupid,
like forget to check oil or coolant levels too repeatedly try to hit absurdly high rpms on a frequent recurring basis.
piston speed should be kept under about 4500 fpm, and even that should not be done constantly.
most engine failures are the result of valve train component or rotating component failures,
use of parts not designed for the stress levels,
detonation or lack of proper clearances and lubrication and lack of proper cooling,
control those factors and your engine lasts considerably longer
my dad always stated..

"A couple hours , well spent in doing carefully documented &,detailed research,
before.... jumping head first off the dock,
into any project,....can prevent you from wasting month's of non-productive work and a wheel barrow full of cash!!"

related threads
I know that a good deal of the money I probably would be spending on my dream project,
of installing a killer BBC in one of my corvettes with a 4l80E transmission,
goes too keeping this web-site up and running,
or supporting my sons family who seems to have permanently moved into my home,
and lets me basically support him now that hes too sick to work,
so getting financially side tracked is hardly rare!
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When your planing to build a performance car, I've found it helps,
you see progress being made and prevents you from getting discouraged as easily,
if you work on accumulating components for each of the 8 basic sub assemblies,
and checking off your list those components and grouping those on a separate shelf,
as doing so tends to allow you to see more consistent progress,
being made, and you get a feeling your getting someplace.
look through these threads
yeah I know a few of you would rather gargle broken glass scrap than read links and sub-links but trust me if I tell you in the long term, youll gain a wealth of info you need to use to build an exceptional and durable engine, the secret is mostly in getting each component working to its maximum efficiency and in maximizing durability, you won,t win many races or enjoy owning the car if it spends most of its life being repaired or waiting for replacement components to arive, and in many cases simply thinking things through, and selecting the best quality matched components you can afford, and carefully installing them with the correct clearances and lubrication and cooling goes a long way to reaching that goal.
if you, as the engine builder, have a choice.
ID suggest you always give up that 5% in peak power potential,you might get by running on the ragged edge , if you can gain 10%-20% increased durability, by not pushing things to just at the point the parts are likely to fail, and knowing that point takes either experience or knowledge gained by watching others fail. and in many cases thats an option if you fully understand exactly how and why things are intended to function.
porting that intake port wall paper thin , pushing the rpm's you your constantly bouncing the valve train into valve float, or not having consistent oil flow on the critical components might seem like a route to gain an edge in power needed to win races, its much more likely to see you drain your checking account trying to do expensive repair work when components get pushed to the point of catastrophic failure.


notice how the rod bolts come close to the cam bearings and cam lobes,as the pistons reach top dead canter in the bores, this clearance must be individually checked and should be no less than about .060 (generally you cam use a LARGE plastic tie-wrap, you must install the timing set and index the cam correctly to get a valid clearance , as the cam lobes rotate and at some point they can be incorrectly indexed too hit the rods, while they would not if correctly timed.


placed between the cam lobe and connecting rod bolts or connecting rod shoulder areas to check clearances as the soft tie-wrap will not damage the cam lobe while you verify clearances)







why you need to verify the cam to rod bolt clearance

rods that use bolts with nuts like pictured below will be weakened if excessively clearance ground


stroker profile rods offer more clearance to cam lobes, and yes the stroker clearanced profile rods are available in both (h) and (I ) beam designs

on some stroker applications SOME rods need to have the bolts ground for cam lobe clearance
first step.

before you start panicking and potentially wasting money and time.
would be to assemble a single piston and rod assembly without rings,
but ideally with some old bearings on the crank and connecting rod and install the cam, in the block
( indexed with a simple,dot to dot timing on the timing gear sets should be ok at this point)
move that connecting rod and piston to all 8 locations and very carefully verify clearances (remember the rod clearance bevel faces the crank counter weight and the piston valve clearances face the outer block)through the full 720 degree rotational cycle, remember the cam spins at 1/2 the crank speed so the cam lobe comes close to the rod every other rotation,
and actually verify you DO, have or DON,T have a potential clearance problem
theres zero sense in runninbg around pulling your hair out and screaming until,
theres actually a PROVEN ISSUE too SOLVE (THERE MAY NOT BE!)
now if you find theres an issue to be solved you proceed using facts
and while your checking the cam lobe to connecting rod clearance check the connecting rod to block clearance ....yes the same minimum .060-.080 clearance is suggested

generally its a minor easily done clearance job





don,t forget to verify the cam to connecting rod clearances
a cams VALVE LIFT is determined by the DISTANCE the lifter moves as the cam rotates under the lifter base as it moves from the cam lobe base circle
(the closest the lifter comes to the cams center line)
up to the cam lobes ramp to the lobes peak,
(the furthest the lifter up off or from the cams center line)
don,t forget to carefully check the piston skirt to crank counter weight clearance, it should be a MINIMUM of .080 thousands

heres some pictures taken of an engine assembly that use a crank designed for a MINIMUM of a 6.25" connecting rod that was used with a 6.135" connecting rod



you can clearly see where the piston pin boss was being hit bye the counter weights, even though the builder checked one piston and found it had .025 clearance during assembly


the result was a trashed engine with lots of damage


(1) BLOCK (bearings, freeze plugs main caps and machine work)

(2) ROTATING ASSEMBLY (crank, rods pistons, rings, flywheel,damper etc.)

(3) CYLINDER HEADS and VALVE TRAIN ( valves, valve springs, cam, timing gears, rockers, valve guides, push-rods lifters . etc.)

(4)INDUCTION(manifold, throttle body, sensors, carbs, supercharger, injection , fuel pump, fuel pressure regulator injectors etc.)

(5) DRIVE TRAIN ASSEMBLY COMPONENTS(clutch, stall converter, transmission ETC.)

(6) ignition system (distributor,coils, ignition wires, magneto etc.)

(7) LUBE SYSTEM (oil pan, oil pump, windage tray,oil cooler, ETC.)
these threads and links and sub-links might help

(8) EXHAUST (headers and exhaust system, mufflers ETC.)

please let us know the parts list and machine work you have done,
and the eventual results you get and your driving impressions.
once the cars engine is installed and tuned and tested out.
you'll have much better results if you don,t randomly select parts,
and keep in mind a trusted machine shop, and listening too advice from an experienced machinist,
can help prevent you from a great many mistakes ,Try to find some friendly, knowledgeable older geezer,
with 30-45 plus years of experience building race engines

and if your going too build an engine for bracket racing,
you,ll want to get the static compression up to about 11.5:1-12.5:1 ( MINIMUM,)

and use race octane fuel, (do the required calculations) not crappy pump gas.
youll want to build the lightest weight car you can, because weight,
or increased mass takes more energy (hp) to accelerate,
building an engine to maximize torque over the intended rpm range,
and gearing the car too match that, and tuning the tires and suspension to use that available torque is key,
as it tends to maximize your cars potential.

if you find the rotating assembly is more difficult to rotate than you expected, you may want to verify some clearance issues that get over looked at times,
theres also some, other potential issues,
theres a slight potential for the piston wrist pins too not rotate effortlessly in the piston pin bores ,

that may add to the difficulty in rotating the assembly in the block.
the piston rings must have vertical and back clearance in the piston ring grooves




Piston Ring Groove Clearance
Pistons are grooved to fit rings that seal the cylinder’s compression and allow for lubrication of the cylinder walls. Piston rings come in a set. There are two compression rings. The top ring is affected by the most cylinder compression pressures. The second compression ring reinforces the top ring. The third ring down is the oil ring. It controls lubrication between the piston and cylinder bore.


Place the new ring into the top piston groove, and then place a feeler gauge into the gap between the new ring and the upper land. Move around the pistons groove and obtain a few measurements. Compare this reading to specifications. If this reading is too much and the gap is too large, the piston must be replaced. The top ring takes the most compression. This causes the ring to slap against and wear the lands in the piston groove.



and of course the pistons must have the correct piston too bore clearance. and connecting rod can only be installed facing one direction






bearingoffset2.jpg dynamic Comp Ratio.htm


this has never been a cheap or easy hobby and the more you learn, the more you realize there's always a situation where you have just upgraded several components only to find that that upgrade resulted in the need to , upgrade some other system , like the ignition, brakes, cooling or drive train durability.
you'll always find you are forced to learn new skills and upgrade the quality and durability of parts if your intention is to vastly increase the cars power, high speed stability, braking, cooling and over all driveability, especially if you think racing against similar cars at higher speeds is your goal.

you might not initially realize all the mods that a true performance upgrade requires, especially if it's being done correctly, and yeah, it's always going to be much more expensive than you might have initially thought as there's alway incidental but required upgrades.
constant research on your options and carefully balancing the potential performance against the potential cost and difficulty in matching all the components, and verifying they fit and function properly,
as to not compromise the max performance, can at times be rather difficult, especially when you will be forced to conclude there's always the need to do at least some custom parts fabrication work' there's almost zero chance for an example that you can install a tall deck,BBC engine in lets say a 1996 corvette without having custom motor mounts, transmission mounts a upgraded rear differential, a custom exhaust and custom headers, and obviously installing better brakes more gages, a much bigger and more efficient cooling system, an oil cooler, a transmission cooler and a dozen other upgrades.

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(Words and photos by Scott Liggett) – We know many Bang Shifters are not made out of money. We are in that crowd ourselves. Any way we can save money on our project cars allows us to have a better car or truck. The easiest place to save money using our time and sweat instead of paying shop labor rates. One place many people often over look is the assembly part of rebuilding an engine.

Sure, there are few that have access to the tools necessary to do machine work on our engines, but putting together an engine doesn’t require fancy tools. A good torque wrench is about the only fancy tool that we needed putting together a 454 we recently had machined for a rebuild. Since we were getting estimates up to $500 from machine shops to assemble our engine, we decided that we save that money by taking the time to do it ourselves. That is just putting the new parts and machined block, crank and rods back together.

Yes, we were a bit apprehensive to do it. Engines are not cheap to get built these days. That can scare many people away from attempting this kind of work. But, after talking to some friends and our machine shops, we decided to go for it.

Truth be told, this is our second time assembling this 454 after machine work. But, the reasoning for this had nothing to do with the machine work done, or assembly job. We had two things that had us pulling the engine again after only 10,000 miles. First, we had constant lifter noise after the engine warmed up. Second,was piston slap from only doing a dingle ball hone with the original pistons with new rings and bearings. All the lifters failed a bleed down test and the pistons had too much clearance after the home honing job. This time we bought new pistons and had the block completely machined top to bottom with a .030 over bore. The rotating assembly had to be balanced for use with the new pistons.

You want to work in as clean as space as possible to avoid debris getting into your fresh engine. We were working in Scott’s one car garage at his house, which is pretty clean. We kept the engine covered by old, but clean towels in between days we were working on the engine.

This is how we received our 454 block back from the machine shop. The guys over at BluePrint Engines did the work for Scott and the block came back looking like a brand new casting, not like a 45 year old block. In case it isn’t obvious, the first thing to do is to get it on an engine stand. We got our from Harbor Freight, but this one is the big dog. A fully dressed 454 weighs near 700 lbs. They also replaced all the freeze and galley plugs for us.

After taping off the areas we didn’t want painted, we shot the engine in Chevy Orange. We were told not to paint in the oil filter housing, so we took some time to clean that up later in the build.

Before doing any assembly, we decided to see if our factory windage tray would work with the Milodon 7 quart oil pan and Melling high volume oil pump we are using. We also decided to upgrade to ARP main studs instead reusing the original main bolts for better support for the crank. The studs have provisions for the windage tray.

Even though the Milodon pan has these dimples to make room for the studs, we had to dimple them a bit more so the pan would sit flush on the block.

BluePrint Engines did the crank turning and balancing for us as well. The crank was standard when we took it to them, but polishing did not get all the scratches out of the bearing surfaces, so we had it turned .010/.010. They balance all their rotating assemblies below 2 grams, but ours came out .41 grams on the front and .89 grams on the back. We first laid in the block sides of the main bearings and carefully laid the crank in the block without any assembly lube at this point. Forged big block cranks weigh in excess of 60 pounds, so if you can get help to set it in the block, do so. Dropping it on your bearings, or your foot, would not be good.

Next, we cleaned the main caps with Brakleen and a lint free rag before installing their half of the main bearings. Even though the block was thoroughly washed after machining, their was still some dirt after sitting around for two weeks before getting to work on it. The rear main seal is not needed at this point.

We got some Plastigauge from the local parts store to double check bearing clearances. Your machine shop should have done this during the machining process with their measurements. You are just making sure. Taking your time and being anal during engine assembly is a good thing. After laying the piece of waxy, plastic string across the bearing surface on the mains, you place the main caps on and torque them down to manufacture specs. In the case of our 454, it was 105 ft lbs.

Next, remove the main caps and check the measurements on the Plastigauge’s paper cover. Our Chevy Factory Overhaul Manual says that the main should have between .001 and .003 clearance. All of our mains had .015 readings. This is only approximately, but you are being sure of what you got before you have the engine together and running. The alternative is finding bearing material in your oil filter after a few miles. Not a good day. Repeat this process on all of the main caps and bearings.

Remove the crank from the block, then get out your engine assembly lube and liberally cover the main bearings. Then, you need get out the rear main seal from your engine gasket set. Fel-Pro includes instructions on which way it is suppose be installed to keep it from leaking all over your driveway.

Some people say you should install the rear main seal halves offset slightly for better leak protection. Others don’t. We did.. We did add a little bit of RightStuff sealant on the seal ends for added security.

Now your crank is done. Time to move on the connecting rods and pistons. We used the same plastigauge on each of the rod bearings to check their clearances as well.

For the purpose of checking the bearing clearances with the pistons already installed on the rods, we did this before installing the rings on the pistons. This made sliding them in and out of the bores much easier. The rods were stamped with their numbers when Scott took the engine apart before machining, but he wrote big numbers on the end caps cause he is slowly going blind like all middle aged men. The machine shop added those colored paint dabs as part of their checks and rechecks. They mark the side of the rod that has the rod bearing tabs. The tabs should face towards the outer part of the block.

Torque the rod bolts to their recommended specs. Before removing the rod caps and checking the clearances with the plastigauge you used, check the side clearances on the rods. We checked between the rod pairs and between the rods and the crank sides. On our 454, those clearances should be between .015″ and .021″. Bearing clearances on our 454 is the same as mains, .001″-.003″.

After checking the rod clearances were all good, we moved on to installing the rings on the pistons. Even if you buy rings that are supposed to be pregapped, we suggest you check the clearances anyways. Remember what we said about being thoroughly anal? Our rings came with our piston set from Keith Black. They are moly rings, but we had to gap them. It is tedious, but necessary. Too tight of clearances and you will break them and the ring lands on the pistons. Too loose and you can have oil usage problems and lack of power. We wanted to get consistent measurements, so we always made sure they were the same distance down in the bores each time.

Using a feeler gauge find the clearance on the ring. The measurement will depend on the type of rings you are using and the intended purpose of your engine. The use of nitrous and boosted engines need more clearance for the added cylinder pressure and heat. We wanted .021″ on the top ring, and .024″ on the second ring.

Our rings needed a bit of filing. here are ring gapping tools available from many companies, but we put a metal file in the bench vise and gently ground them a bit. Do a little bit at a time. Don’t get in a hurry. It’s better to go back to the file a few times, then over gap your rings.

Once all 16 rings are gapped, they need to be installed on the pistons. Certain types of rings are reversible. Ones that are not often have a dot to which side is the top. Keith Black’s instructions said not spiral them onto the pistons. This means we needed to spread the two ends apart in order to get the rings on the pistons. There are many inexpensive tools for safely doing this. We should have gotten one ourselves as we got impatient and broke one of the rings trying to install it. The oil rings are the easiest to install and are usually three pieces.

Since ring sets don’t come with spares, we had to order another set. We were able to get another set of the same style and material from another brand, but it will work.

Clock the rings 180* apart before moving on to installing the pistons and rods in the engine for the last time.

Now that there are piston rings on your pistons, getting them into the block is a little more work. So not damage the bearing surfaces on your crank, cover the rod bolts with rubber hoses or specific boots so not to scratch crank. We just used 3/8″ fuel line.

Now, it’s time to install your rods and pistons for the last time. You will need a ring compressor. There are fancy, size specific ones available. We just used this $18.00 one we got at Napa. Set the rod into the bore, then tap the compressor flush with the deck surface of the block. Be sure the valve reliefs in the pistons are oriented in the correct direction.

We used the rubber handle of a ballpeen hammer to tap the piston down into the bore. A dead blow, or a specific dead blow piston driving tool will work as well. Just do not use anything metal against the piston face. That would be bad.

With this type of ring compressor tool, you do need to stop a couple of times during the piston installation to be sure the compressor stays flush with the deck surface. If the piston ring slips out, you will be starting over.

Use the engine assembly lube on the rod bearing halves just like the main bearings. When you get the piston driven down to where the rod meets the crank throw, put the rod cap on the rod and tighten the bolts down to recommended specs. Our ARP rod bolts were torqued to 50 ft lbs.

You will need to install your oil pump next. Don’t forget the oil pump pickup screen as well. We are using a Melling high volume pump and a pickup screen for use with a 7 quart oil pan. This pickup screen is pretty much dummy proof in it’s installation. We still checked for it’s clearance to the bottom of the oil pan. Before installing the oil pump, make sure you install the oil pump drive shaft first, or the day you fire up your engine will not be a good day. The oil pump’s bolt gets torqued to 60 ft lbs on our 454. The rotating assembly installation is complete.

We took some extra time to install our factory windage tray for better oil control and a few more horsepower. Our ARP stud kit included the four longer studs for its use. Be sure to check the rod clearance under the windage tray. Rotating parts need at least .060″ clearance.

Flip the engine back over for the camshaft installation. Apply liberal amounts of moly lube to the camshaft lobes and bearing surfaces. We only add the moly lube to four lobes and a bearing surface at a time, then install the cam up to that point. Then add some more to the next set of four. The keeps your hands cleaner and it easier to install. We used a 5/16″ x 6 inch long bolt in the front of the cam for more leverage. Or, you can buy a cam handle. We’re cheap.

We used this cam moly lube we got from Isky. This tub has been used on five or six cams and we still have plenty left.


the tall deck block requires a longer reach distributor shaft thats about 0.28 longer thus the need for the adjustable collar on the distributor adding the extra reach to get the oil pump drive and drive gears to properly align and mesh.


be aware theres an oil supply passage in the lower block skirt, and coolant passages that extend quite low on the mark IV blocks so you can't just grind excessive rod clearance, for crank counter weights and large, longer stroke , stroker type crank's to the same extent you can get away with on the later MARK V and VI blocks, or the far better choice of a DART aftermarket block, so you'll need to be careful,doing clearance grinding,I would advise limiting stroke lengths to a 4.375" max, even in the tall deck truck MARK IV blocks, the later Mark V and VI blocks have that passage up near the cam tunnel
The last thing to do is install the timing chain. First, drive the crank gear on the crank with the round dot on the crank key way and the dot pointing straight up. The cam gear goes on with the dot pointing straight down. This Cloyes timing set has a three way set up for advancing, or retarding the cam 4*. We installed ours straight up.

That’s it for the short block. The cam’s lifters will go in with the pushrods and valvetrain. It wasn’t all that hard, was it? We did this over a weekend.

blueprint engine blocks


world products blocks

G.M. performance
a few related threads that might help you build a better car

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heres some calculators you might use
gear spread sheet that comes in handy THANKS TO 1FATGMC
a few resources to allow you to calculate the ideal results
heres some differant calculators
average the results
its unfortunate but theres always going to be some transaction where machine shops or suppliers drop the ball or screw up.
Ive certainly had more than what Id consider my fair share of less than ideal transactions and dealing with machine shops over the decades,
and you can,t even in most cases point out the ones you should always go too...or avoid simply because many will go for hundreds of transactions,
having hundreds of happy customers.. then a couple totally #$%^& up , totally uncharacteristic transaction's,
and following with a "we just don,t really give a S4$%^& attitude and less than quality parts shipped."
then followed inexplicably reverting back to the normal customer relationship.

a few factors to consider


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Ultimate Guide to Building Chevy-Big Blocks: Cylinder Blocks Instruction

These big chunks of iron or aluminum are indeed the building blocks upon which your entire engine is crafted. Like a raw canvas or flawless piece of marble awaiting the master’s touch, the block is only as good as the casting itself.

Oil passages, lifter bores, and dozens of bolt-hole locations all factor into what makes a good block for a true highperformance or racing big-block Chevy. Most of these machining operations have been handled at the factory, and more often than not, they are going to be right on the money. When it comes time to select your block, you want to start with the right casting for your projected power level, and then find the best machine shop to bring everything to spec.

This Tech Tip is From the Full Book “HOW TO BUILD KILLER BIG-BLOCK CHEVY ENGINES“. For a comprehensive guide on this entire subject you can visit this link:

SHARE THIS ARTICLE: Please feel free to share this post on Facebook / Twitter / Google+ or any automotive Forums or blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link:

Block Selection
The first decision you need to make when it comes to selecting a block for your bruiser is whether to start with a factory production or aftermarket block. For the vast majority of people, the decision is an easy one: you plan to use a stock block, whether it’s one you already own or plan to purchase at the right price. There’s nothing really wrong with a stock block engine. It’s just that the beefier aftermarket or Bowtie blocks have advanced features (such as siamesed bores that can safely be bored to 4.600 inches or more) that contribute to greater power potential.


Gen VI Bowtie block with splayed bolt billet steel main caps. (Photo Courtesy GMPP)


This cutaway of a Merlin III block shows the beefy cylinder walls made possible with siamesed bores. This allows much larger bore sizes than stock 454 blocks and the thick cylinder walls promote better ring seal. Also note the additional head-bolt bosses in the lifter valley, which give extra clamping power for a better head gasket seal. (Photo Courtesy World Products)

Here are the basics: if you plan to produce up to 650 hp (normally aspirated or “all motor” as the sport compact guys say) on the street or 750 hp on race gas, you can definitely get there with a stock-block four-bolt main engine. I limit power levels to 600 hp with a two-bolt main block. For higher power requirements, the aftermarket blocks start to look a lot better.

Let’s look at some examples: say your target power level is 750 hp. You can get there with a stock block 467-ci engine (4.250-inch bore plus .060-inch overbore, and 4.000-inch-stroke crank), but to produce 1.602 hp per cubic inch may require better flowing CNC-ported cylinder heads, a larger camshaft, a full kickout oil pan and matching pump, and other such tricks to produce the power needed. And, you probably have to spin the engine up to about 8,000 rpm, which puts additional wear and stress on all components, especially the valvetrain.

But a 565-ci engine (4.600-inch bore x 4.250-inch stroke) only needs to make 1.327 hp per cubic inch. And you can easily get there by using less expensive heads and a typical high-performance oiling system. You make the power at a lower RPM, which eases wear and tear and takes less of a toll on the valvetrain. And the real kicker is how, when you decide to “step it up” to the next class, bracket, or you just want to go faster, the same parts you needed just to qualify with a 467 really wake up that 565.

Maximum Bore Sizes
When overboring your block, the best way to determine the maximum safe bore size is to use a sonic wall thickness tester, a very expensive piece of equipment that most high-end machine shops will have on hand. The minimum safe wall thickness is .200 inch, but you are better off with a slightly smaller bore (and thus thicker cylinder walls) if the engine will be used on the street or for endurance racing applications such as off-shore boat racing. Most production blocks will easily accommodate overbores of .030-inch or .060-inch as long as there is no evidence of extreme core shift. The best indicator of core shift during the casting process is to look at the lifter bore bosses: the lifter bores should be well centered in their bosses. If there is no visible core shift in the lifter bosses, many 454-based engines are bored to +.100-inch (yielding a bore size of 4.350 inches), and some brave souls have gone as far as +.125-inch, although that is usually best left to drag-race-only applications using some form of block filler in the water jackets to support the resulting thin cylinder walls.

502 engine blocks (8.2 cast on sides of block) will safely tolerate a 4.500-inch bore, which is only .034-inch over their 4.466-inch bore size as produced. The cylinder wall thickness of Bowtie and aftermarket blocks with siamesed bores has varied considerably over the years, but most can safely tolerate bores to 4.600 inches and some are rated up to 4.625 inches. For the amount of money being invested in an engine of that nature, you are best advised to have the cylinder walls sonically checked and hold to the minimum wall thickness of .200 inch.

Stock Blocks
When I refer to stock blocks, I’m talking about original-equipment cylinder blocks found in cars or trucks, as opposed to the Bowtie blocks, which, even though they are “Genuine GM Parts,” were never available in a production vehicle. Always inspect a used engine for damage that is unrepairable, like cracks or excessive overboring, as well as flaws that can be fixed at additional expense, like stripped bolt-holes, main bore misalignment, and uneven deck surfaces.


Aftermarket blocks, like this Dart Big M cast-iron block, may cost more than stock blocks initially but can save you money in the long run as you search for more horsepower.


Original ZL-1 aluminum blocks are scarce as hen’s teeth, but you can buy a brandnew version from GMPP (PN 12370850) with the Mark IV–style two-piece rear main seal. PN 88958696 comes with the Gen V/VI–style one-piece rear main seal. (Photo Courtesy GMPP)


A. Here are the specifications of the front of the block:
B. Main Bore: 2.937 to 2.938 inches
C. Main Caps: (five) two- or four-bolt, 7/16-14 bolt holes
D. Cam Bore: 2.140 inches (number-1), 2.130 inches (number-2 and number-5), 2.120 inches (number-3 and number-4); cam bearing inside diameter: 1.950 inches
E. Crankshaft-to-Camshaft Centerline: 5.152 inches
F. Deck Height: 9.800 inches (standard), 10.200 inches (tall-deck Marine, Truck, and some High Performance)
G. Timing Cover Rail: ten 1/4-20 boltholes (Mark IV, Gen V), two .250-inch alignment dowels G. Water Pump Pads: 3/8-16 bolt-holes, two each side
H. Accessory/Motor Mount Pads: 7/16-14 bolt-holes, two each side
A. Here are the specifications of the front of the block:
B. Main Bore: 2.937 to 2.938 inches
C. Main Caps: (five) two- or four-bolt, 7/16-14 bolt holes
D. Cam Bore: 2.140 inches (number-1), 2.130 inches (number-2 and number-5), 2.120 inches (number-3 and number-4); cam bearing inside diameter: 1.950 inches
E. Crankshaft-to-Camshaft Centerline: 5.152 inches
F. Deck Height: 9.800 inches (standard), 10.200 inches (tall-deck Marine, Truck, and some High Performance)
G. Timing Cover Rail: ten 1/4-20 boltholes (Mark IV, Gen V), two .250-inch alignment dowels G. Water Pump Pads: 3/8-16 bolt-holes, two each side
H. Accessory/Motor Mount Pads: 7/16-14 bolt-holes, two each side

All stock blocks are cast iron except the rare ZL-1 aluminum block, which saw limited production in 1969. It’s a pretty safe bet that all of these jewels are well accounted for, and your chances of stumbling across one in some salvage yard are fairly slim.

Mark IV Blocks
Stock blocks produced from 1965 to 1990 are the original Mark IV design, and were available with either two- or four-bolt main caps, and in three bore sizes (four, if you count the 366T talldeck truck blocks with their miniscule 3.935-inch bores, but I’m not counting them because they are totally unsuitable for any performance big-block buildup). The 396 had a bore of 4.094 inches, the 402 was slightly larger at 4.125 inches, and 427s and 454s share a 4.250-inch bore. All else being equal, there is no reason to start with any stock block other than the larger 4.250-inch-bore blocks.


Muscle-car era Mark IV blocks with four-bolt mains were drilled and tapped for oil cooler fittings just above the oil filter mount. Note the 1/8-inch NPT pipe plugs just above the oil pan rail. These are where the main oil gallery was crossdrilled to feed the main bearings.


Standard big-block deck height is 9.800 inches from the crank centerline to the deck surface, and tall-deck blocks like this one measure 10.200 inches. You can easily spot a tall-deck block by looking at the distance from the top water pump bolt-hole to the deck surface. With a standard-height block, the top of the water pump is nearly even with the deck, but a tall-deck block has .400 inch more material, about the same amount as the diameter of the 3/8-16 bolt-hole. Also, most tall-deck Mark IV blocks have a 1/8-inch NPT oil gallery tap in front of the manifold end rail, as shown here.

Very early Mark IV blocks had a couple of peculiarities you should be aware of. First, 1965 and 1966 blocks used a grooved rear cam bearing with a matching groove in the rear camshaft journal. This groove was designed to supply oil to the lifters, and if a non-grooved bearing or cam is used, there is no oil supply to the passenger-side lifters—this is not good. Second, all Mark IVs through 1967 used the 1950s-era oil canister with an oil filter cartridge inside. The 1968-andlater engines got the traditional spin-on oil filters that we all enjoy changing to this day.

Gen V and Gen VI Blocks
In 1991, General Motors changed several important design features of the Mark IV big-block with the introduction of the Gen V engine, most notably the addition of a one-piece rear main oil seal, and different coolant core passages in the deck surface of the block and heads. Gen V and Gen VI blocks are easy to spot in the wrecking yard; they all have a revised front core that features a distinctive continuous machined boss for the front cover, water pump, and front accessory mounting bosses, giving the appearance of having a frame around the front timing cover. All production engines were fuel injected by this time, so the mechanical fuel pump boss was also eliminated. Most of us “old timers” initially viewed this version of the big-block as something of a disappointment. The supply of good crankshafts, oil pans, and cylinder heads would no longer fit, which limited its performance potential.

Those performance challenges were addressed by a responsive aftermarket parts industry, and soon we had a choice of high-performance cylinder heads designed to work with either Mark IV or Gen V deck surfaces (with the appropriate head gasket for the block being used), two-piece seal adapters allowing the use of traditional Mark IV crankshafts, and performance oil pans designed for the wider rear main cap with its one-piece seal on the Gen V block.


All Gen V and Gen VI blocks came with four-bolt main caps, like this Gen VI 502 block. Gen V/VI main caps are about .200 inch taller than Mark IV caps, and require different bolts or studs. This block has been drilled and tapped to accept a standard 10-bolt front cover; stock timing cover had six bolts.



Gen V and Gen VI blocks feature a priority main oil gallery that runs parallel to the lifter supply oil passage on the left of the block. It is the larger hole at the 3 o’clock position next to the cam bore. The two lifter oil galleries are above the cam bore at the 10 and 2 o’clock positions.


Gen V/VI blocks have an abbreviated oil filter mounting pad with a 1-inch-wide reinforcing rib. The filter sealing surface is nearly flush with the oil pan rail, while it is recessed by 7/8 inch on Mark IV blocks.


502 blocks can easily be identified by the “8.2” designation cast into the side of the block. They feature siamesed cylinder barrels and the finished bore size is 4.466 inches. They can safely be bored to 4.500.

With this kind of parts availability, there’s no reason not to consider a Gen V or Gen VI block as a good starting point for your project engine, with a few caveats. For one thing, production-line Gen V blocks have no provision for mechanical fuel pumps or traditional clutch linkage. These obstacles can be overcome by using an electric fuel pump and hydraulic clutch linkage, but you have to factor in these additional expenses and see how they compare to simply buying a block that has the features you need in the first place. Also, consider the limited cylinder head availability for the Gen V deck surface. There were very few factory performance heads made for this engine family, and these were mostly for the over-thecounter 502 HO engine. The production Gen V heads were all low-performance “peanut” port heads designed to produce good low-end grunt for the truck applications these engines were used in.

There is a good assortment of aftermarket cylinder heads, both cast iron and aluminum, that work on the Gen V, but you have to factor in the additional cost of these premium parts. One often overlooked difference between the Mark IV and Gen V engines is that the taller rear main cap bolts required for the Gen V’s one-piece rear main seal interferes with the original Mark IV oil pump. Gen V and Gen VI engines require matching oil pumps, along with a heavy-duty oil pump driveshaft like GM PN 3865886. On the plus side, all Gen V and Gen VI blocks were fitted with four-bolt main caps.

In 1996, the Gen VI was introduced with additional changes. Probably the easiest feature to spot when trolling for blocks at the salvage yard is the six-bolt composite or aluminum front timing cover. Both the Mark IV and the Gen V used stamped steel front covers with 10 bolt holes. If the cover is missing, just look for the six-bolt pattern, compared to the 10-bolt pattern used on all Mark IV-style engines, including Bowtie and aftermarket blocks. Gen VI blocks also benefit from the reintroduction of the mechanical fuel pump boss and clutch pivot stud boss.

Production Gen VI blocks still have the large water passage and core holes in the deck surface, again requiring the use of Gen V or Gen VI cylinder heads or aftermarket heads designed to fit either the Mark IV or Gen V/VI blocks. Other refinements to the Gen VI include bosses in the lifter valley for the factory hydraulic roller lifter retainer, commonly called a “spider,” although not all Gen VI blocks have this feature. This can be important if your plans call for the use of a hydraulic roller lifter camshaft, because the cost of the lifters is quite a bit more than the cost of the camshaft. If your core engine includes the original GM roller lifters, they may be reused (unlike conventional flat-tappet lifters) as long as they are in good condition, although the stock lifter and guide arrangement is limited to valve lifts of around .600 inch.

If your block does not have the factory roller lifter alignment bosses, there are aftermarket roller lifters available with self-aligning tie bars so you can still use a hydraulic or mechanical roller cam. If you use tie-bar roller lifters, the taller lifter bores require roller lifters that are .300-inch taller than Mark IV lifters, and they are readily available from most cam companies.

Gen V and Gen VI blocks feature a priority main oil gallery that runs parallel to the lifter-supply oil passage on the left (driver’s) side of the block. This feature has two advantages: first, oil from the oil pump goes directly to the main bearings (after being filtered, of course) then on to the lifters and cam bearings; and second, relocating the oil gallery from the driver’s-side oil pan rail (Mark IV location) means there is no chance of breaking into this passage when grinding the block for additional connecting rod clearance, or when fitting the block with splayed-bolt main bearing caps. This feature has proven to be so popular that it is now standard on most aftermarket cylinder blocks, as well as Gen V/VI blocks.

There is one more OEM block that was found in the last production bigblock engines used in trucks from 2001 to 2006, and that is the 8.1L (496 ci). While General Motors is nearly mute about this engine, you could call it the Gen VII big-block, because it has substantial differences from all other big-blocks. It uses entirely different symmetrical-port cylinder heads, which are bolted to the block with 18 head bolts instead of the usual 16 found on Mark IV and Gen V/VI production blocks. And no, the 18-bolt pattern is not the same as the Bowtie or aftermarket 18-bolt pattern, both of which use two additional bosses in the lifter valley. This engine, designated the “Vortec 8100” or RPO L18, has a tall-deck block with a 4.25-inch bore and a cast crankshaft with a 4.37-inch stroke. It is fully computercontrolled, and features a distributorless coil-near-plug ignition system and multipoint electronic fuel injection (EFI). It relies upon crankshaft and camshaft position sensors, and has redesigned water pump and coolant passages.

In short, it is a unique animal in the big-block jungle, and very few other bigblock performance parts fit. It does have both early- and late-model-style motor mount bosses, meaning it bolts into any engine compartment originally designed for the big-block, but its tall-deck design and different accessory mounting locations likely require some surgery with a cutting torch. There are aftermarket sources for powertrain control modules, if you really want to tackle something different in the world of big-block engine swaps. The block is readily identifiable by the “8.1” designation cast into the sides of the block.

Another block of considerable interest to hot rodders is the 502, sometimes referred to as the 8.2 liter, which is easily identified by the large “8.2” designation cast in the sides of the block. The 502 was never installed in production vehicles, though many were used by the marine industry, especially Mercury Marine. It features siamesed cylinder barrels and a finished bore size of 4.466 inches. They can safely be bored to 4.500 inches, which, even with the stock 454/502’s 4-inch-stroke crank, yields a displacement of 509 ci. Drop in a 4.250-inchstroke crank, and you’re looking at 540 cubes (actually 540.7, but everyone calls them 540s). This makes the 502-ci block an ideal start for a moderately high horsepower street, marine, or drag race engine, but remember that it is basically a production-line block and does not tolerate large overbores. It is not the same casting as the factory-produced highperformance Bowtie blocks. These blocks are available from GMPP (PN 19170540).

General Motors Performance Parts Blocks
While never installed in production vehicles, General Motors Performance Parts (GMPP) offers several replacement four-bolt main blocks suitable for performance applications. PN 19170538 is a non-siamesed-bore block with a 4.250- inch bore that is a hybrid of the original Mark IV and the newer Gen V/VI designs. Because it is a production-based block, bore size should be limited to 4.310 inches. Like all Gen V/VI blocks, it has a one-piece rear main seal and must be used with a Gen V/VI crankshaft or adapted to the older two-piece rear main seal for use with Mark IV cranks. It is machined for the Gen VI 6-bolt front cover, but there is adequate material to drill and tap the block for use with traditional 10-bolt covers, if desired.


GMPP block PN 19170538 is used in the 454 HO short block. This production-based non-siamesedbore block with a 4.250-inch bore is a hybrid of the original Mark IV and the newer Gen V/VI designs. (Photo Courtesy GMPP)

This block features traditional Mark IV features such as a machined fuel pump pad, clutch pivot stud bosses, and deck coolant passages that have been designed to seal properly with either Mark IV or Gen V/VI cylinder heads. It incorporates many of the Gen VI block’s desirable features such as provisions for hydraulic roller lifters, redesigned priority main oil passages, and the standard Gen VI oil filter mount with oil cooler fittings in the pan rail surface. This block is used in the ZZ427, the 454 HO, and the ZZ454 crate engines offered by GMPP.

PN 19170540 shares the same traits as the PN 19170538 block, but has siamesed 4.466-inch bores that may be increased to a maximum bore size of 4.500 inches. This is the block that General Motors uses for all of its 502-ci crate engines, including the ZZ502.

Bowtie Blocks
Beginning in the 1980s, Chevrolet rewarded its legion of Pro Stock and other big-block racers with the introduction of the Bowtie blocks, which have substantial improvements over regular production-line blocks in terms of strength and potential bore sizes. The most notable of all these features was the introduction of siamesed bores, which have no water passageways between the individual cylinder barrels. The thickness of the cylinder barrels was increased enough to accept 4.500-inch and larger bores while still retaining a wall thickness of .200 inch or more. There have been many versions of the Bowtie blocks, in Mark IV, Gen V, and Gen VI configurations, so the maximum bore size varies with the individual block casting number. Many can be safely bored to 4.600 inches.

Mark IV Bowtie blocks still used the original oil passage design, which I like to call side-oilers (not to be confused with Fords of the same name), since the main oil gallery is a drilled passage along the left side of the block just above the pan rail surface. Gen V and Gen VI Bowtie and production blocks feature a priority main oiling system, in which the main journals receive the oil before the lifter bores, ensuring that the most critical components in the engine are the first stop on the oil supply route.

You can easily identify the difference between the side-oilers and the priority main blocks by looking for the four 1/8-inch national pipe thread (NPT) plugs along the bottom left side of Mark IV blocks. These plugs cover the opening where the factory drilled intersecting holes to feed the main bearings from the main oil gallery. This applies to production blocks, as well as the Bowtie blocks, so it is one more quick and easy way to distinguish Mark IV blocks from Gen V/ VI blocks.

Another major benefit of all Bowtie blocks is the extra-thick deck surface with blind cylinder head-bolt holes. The thicker-than-stock decks are more stable under high loads, such as ultra-highcompression ratios, nitrous, or supercharged applications. Any time power production goes up, the load on the cylinder head and block junction surface increases, and the thicker decks are simply more stable and provide a better clamping force for the head gaskets. The blind head-bolt holes require no thread sealant, and positively eliminate the ageold problem of engine coolant leaking into the engine through the head-bolt bores in the head. Most Bowtie blocks also feature additional head-bolt bosses in the lifter valley, providing six-bolt clamping around every bore for superior gasket seal. Compare this with the smallblock, which has five bolts per cylinder, and Ford/Chrysler designs, which must get by with only four per hole. Those poor non-Chevy guys…

General Motors didn’t stop there: Bowtie blocks have been beefed up in the main webs as well, some more than others. There are short-deck (9.8-inch) and tall-deck (10.2-inch) versions of the Bowtie blocks, and some feature splayed bolts on the center three main bearing caps for additional crankshaft support. This little luxury item won’t add any performance to your basic 600- to 800- hp big-block, but it gives peace of mind when power levels exceed 900 hp.

GMPP Drag Race Competition Engine Blocks
GM Performance Parts currently offers two versions of this exotic iron block engineered to meet the specific needs of NHRA Pro Stock drag racers. Both are short-deck, semi-finished blocks with 4.900-inch bore spacing (4.840 inches is stock), and they are the spec blocks required by NHRA for GM competitors. They are supplied without head-bolt holes or lifter bores, allowing customization by the individual race teams to suit their needs. They may be machined to locate the starter on the left, allowing the use of oil pans with a full-length kick-out on the right side. The distributor-hole location has been moved to behind the lifter valley bulkhead and requires the use of special Drag Race Competition Engine (DRCE) camshafts. Side-motor mount pads have been eliminated, requiring the use of race-style front and rear motor plates.

The DRCE 2 (PN 24502572) is cast from traditional gray iron and comes with a 9.525-inch deck height that may safely be machined to 9.000 inches.


How do you know it’s a Bowtie block? Well, you can carry this book around with you and check the casting numbers listed on pages 25–27, or, even easier, look for the prominent Bowtie logo cast into the side of the block.


Most Bowtie blocks feature splayed-bolt main caps on the three center mains for added bottom-end strength.


Gen V and Gen VI Bowtie blocks have been available with both the productionstyle one-piece rear main seal and with a two-piece adapter and Mark IV–style rear main cap for use with traditional Mark IV cranks and oil pans. Unlike their production counterparts, Gen V and Gen VI Bowtie blocks have small round coolant passages in the deck surface, and they accept all design cylinder heads, including traditional Mark IV heads. (Photo Courtesy GMPP)


DRCE 2 block (PN 24502572) for Pro Stock competition comes without head bolt-holes or lifter bores. It features a Chevy/Pontiac/Oldsmobile bellhousing bolt pattern and in-block distributor-hole location. Pro Stock racers use dry sump oiling systems and front-drive distributors, so this hole is usually blocked off. (Photo Courtesy GMPP)

The camshaft bore is raised to 5.750 inches (stock is 5.152 inches) and the semi-finished 4.500-inch bores may be enlarged to 4.700 inches. The oil pan rails are spread .400 inch per side.

The DRCE 3 block (PN 25534406) is cast from compacted graphite iron for its superior strength and resistance to bore distortion. The 9.250-inch deck height may be reduced to 9.000 inches and the cam bore has been raised to 7.067 inches. The semi-finished 4.590-inch bores can be bored to 4.700 inches and the oil pan rails are spread to 12 inches. Main bores are 2.500 inches (409 Chevy) and they accept a special nine-journal camshaft with 60-mm bearings.

Aftermarket Blocks
Aftermarket blocks are standard fare for most serious big-blocks built these days, not only for extreme competition but for high-end street and weekly bracket racers as well. They are available in cast iron, cast aluminum, and fully machined billet aluminum configurations. Most follow the Mark IV blueprint and accept original equipment–spec parts such as cylinder heads, oil pans, starters, and water pumps, but there are also “mutant” variety blocks with specialized features such as spread oil pan rails for long-stroke clearance, raised cam bore locations, and spread-bore blocks with a bore spacing of 4.900, 5.000, 5.200 inches or more (stock bore spacing is 4.840 inches).

Brodix, Inc.
Long known as a leader in the field of high-performance and racing aluminum cylinder heads, Brodix also manufactures A-356 virgin aluminum blocks for the big-block Chevy in a variety of stock-replacement or custom configurations. They feature splayed billet main caps made of 1044 steel and coated with black oxide, and additional head bolt lugs in the deck area provide additional head gasket clamping. The main bulkheads have been strengthened and the lifter valley includes reinforcing ribs to prevent flex under high-power, high-load conditions. The lifter oil gallery is easily restricted from the front using Brodix oil restrictors (available separately), and a plug kit is provided with these blocks.

The 8B 2000A block is available in short-deck (9.800 inches) or tall-deck (10.200 inches) versions, and is a direct replacement for conventional Mark IV blocks with 4.840-inch bore spacing and standard cam location. It accepts either stock or stroker oil pans. The cast-iron sleeves, available in two bore sizes (4.480 or 4.590 inches), are retained by 1/4-inch registers, and may be bored up to 4.600 inches (small-bore sleeves are available on request).

The 8B 2000C block features a .400- inch raised cam location and your choice of 9.800-, 10.200-, or 10.700-inch deck heights. The 8B 2100C block adds your choice of 11.100- or 11.200-inch deck heights, and the 8B 2200C block can be had in 11.500- or 11.625-inch deck heights.

The 8B 2000 series blocks may be ordered with conventional big-block Babbitt cam bearings, 50-mm roller bearings, 55-mm roller bearings, or 60-mm Babbitt bearings. Lifter bores are standard Chevrolet (.842 inch) or Chrysler (.903 inch) with larger sizes available. Stroke clearance is 4.750 inches with standard cam location blocks and 5.000 inches with the raised-cam blocks (additional machining required).

If a mountain motor Rat is in your sights, you want to take a good look at Brodix’s fully CNC machined 5000 series aluminum blocks with 5.000-inch bore spacing. These blocks feature a 1.000-inch raised cam location and your choice of cam bearing and lifter sizes. Deck heights are 11.200 or 11.625 inches, and all are designed for dry sump oiling systems. Bore size as delivered is 4.585 inches, and the thick wall sleeves allow bore sizes up to 4.700 inches, which, combined with a 5.000-inch-stroke crank, gets you 694 ci of tire-frying power! Of course, Brodix also manufactures 5.000-inch bore space spread port cylinder heads that are the perfect match for these blocks.

CN Blocks
CN Blocks produces fully CNC machined aluminum blocks whittled out of a solid chunk of forged aluminum. According to CN Blocks, its billet aluminum blocks have more than 36-percenthigher tensile strength than a cast 356 aluminum block, with a yield strength that is 66 percent greater than cast blocks. As a result of the greater material strength of the billet aluminum, you can expect less cylinder liner distortion and a better piston ring seal, reducing blow-by and producing more force on the crankshaft and improved horsepower.


Brodix 8B 2000C tall-deck block. (Photo Courtesy Brodix)


Brodix 8B 5000C tall-deck block featuring 5.0-inch bore spacing and a 1-inch raised cam bore. (Photo Courtesy Brodix)

Obviously, the cost to produce a 100-percent CNC-machined block is far higher than traditional cast-aluminum blocks, but many top racers in the IHRA Pro Stock and Pro Mod ranks rely on these whittled aluminum gems when the need for maximum performance outweighs capital expenditure concerns. Most of these blocks are available as either “dry” or “wet” blocks. Dry blocks have no coolant passages and are used only for drag racing where the short running time does not require coolant circulation. You can custom order a block from CN Blocks to just about any specs you provide, but the following are some of its standard offerings.

A splayed-bolt main cap block is available in four configurations: a traditional Mark IV replacement-style block with standard 4.840-inch bore spacing, 9.8-inch deck height, and stock cam location; a tall-deck (10.2 inches) block with raised cam; a 4.900-inch-bore-spacing block with raised cam; and a 5.000-inchbore- spacing block with raised cam location.

Cross Bolt blocks are intended for serious blower racers utilizing big-block Chevy-based engines. All five aluminum main caps are cross-bolted using 9/16- inch tool steel main studs and 1/2-inch side bolts; a custom Keith Black (KB) Olds or CN Blocks wide oil pan must be used with these blocks. Cam bearing sizes are standard BBC, 2.125 inches (460 Ford), 55 mm, 60 mm, or 65 mm. You also have your choice of lifter bores: .842, .904, .936, 1.00, or 1.062 inches. Blocks may be ordered with or without a distributor hole for racers who use a dry sump oil system and front-drive distributor.

The 1040Y can be used as a replacement block for KB Olds or Arias New Century blocks, and the 1041Y raises the cam .400 inch for larger cam cores and better pushrod geometry. The 1050Y and 1070Y feature 5.000-inch bore spacing, and the 1050Y features spread .160-inch mains and a +.400-inch-high cam. The 1070Y raises the cam +1.0 inch, and these blocks allow you to use bores of 4.600 to 4.750 inches. Dual starter bosses allow the use of full kick-out oil pans with leftmounted starters.

Dart Machinery
Founded by Richard Maskin, one of NHRA Pro Stock’s pioneers, Dart has been making outstanding blocks for Rat racers for years. Most Dart blocks for big-block Chevy engines are patterned after the Mark IV block, but are designed for hardcore racing, addressing all the weaknesses of the factory castings. Extra-thick decks, siamesed bores, enlarged water jackets, priority main oiling, four-bolt main caps, and finished main bearing bores and cam tunnels make it easier to build superior racing and performance engines.

The Big M block is available with deck heights of 9.800 and 10.200 inches, and bore sizes of 4.250, 4.500, and 4.600 inches. The priority main oil system features a stepped main oil gallery (9/16 to 1/2 to 7/16 inch) to increase the flow of oil to the crank at high engine speed (RPM), and the front oil crossover eliminates internal oil leaks around the distributor shaft. There are two slotted head stud bosses on both sides of the lifter valley so you can use studs instead of hardto- install bolts to take the place of the “missing” head bolts.


For mountain motor addicts, CN Blocks makes a series of 5.300-inch-bore-space billet aluminum blocks. These blocks are designed for a minimum bore size of 5.000 inches, yielding displacements in excess of 900 ci. The 5300 series features a 1.917-inch raised cam bore machined for 65- or 70-mm cam bearings and they may be ordered with head-bolt patterns to fit Alan Johnson, Sonny’s GM Hemi, or Sonny’s GM Wedge 5.3-inch cylinder heads. (Photo Courtesy CN Blocks)


CN Blocks’ Cross Bolt billet aluminum blocks are intended for serious blower racers who need the ultimate in bottomend strength. They are available with standard 4.840- or 5.000-inch bore spacing and cam bore locations up to +1.000-inch raised. (Photo Courtesy CN Blocks)


The Dart Big M Sportsman block is available with deck heights of 9.800 and 10.200 inches, and is fitted with ductile iron fourbolt main bearing caps. (Photo Courtesy Dart Machinery)


Manufactured from virgin C355-T61 aerospace aluminum alloy, Dart’s Aluminum Big M block is a conventional Mark IV configuration that retains all production dimensions for compatibility with standard components. (Photo Courtesy Dart Machinery)


Dart’s Race Series tall-deck block is available with deck heights up to 11.100 inches. (Photo Courtesy Dart Machinery)


Most big-block Chevys used in racing cars are mounted with a 1/4-inch-thick mid-plate between the engine block and the transmission, and require longerthan- stock bellhousing dowel pins. The stock diameter is .619 to .621 inch, and some racers try to use common 5/8-inch (.625-inch) dowels. That’s going to require a pretty big hammer, and may damage the block from the excessive force needed to drive them in. These dowel pins from Brodix and Speedway Motors (PN 91025840) are the correct diameter and are long enough for use with motor plates.

Big Ms are fitted with billet-steel fourbolt main caps for ultimate bottom-end strength, and they are machined on precision CNC equipment to ensure quality and to eliminate the need for additional machining. Another nice feature is the use of coated cam bearings, which have an annular groove on the back side and three oil holes to better lubricate the cam journals. The Big M Sportsman block was designed to be an even more affordable version of the Big M block, and is fitted with ductile iron four-bolt main bearing caps. All other features of the Big M are retained in the Big M Sportsman blocks.

The Dart Race Series block is for racers wanting to build real mountain motors—up to 763 ci—and it offers crank-to-deck dimensions of 10.600 and 11.100 inches, nearly 1 inch taller than the factory tall-deck block. The camshaft is raised .600 inch above the stock location for improved connecting rod clearance with stroker cranks, and the block is available with either 4.840- (standard big-block) or 4.900-inch bore spacing. The oil pan rails are spread to increase clearance for the connecting rods and crankshaft counterweights, and it can be ordered with various lifter locations and provisions for symmetrical or siamesedport cylinder heads. You can specify 2.125-inch (standard), 55-mm, or 60-mm roller cam bearings, and the lifter bosses can be machined to accommodate a variety of valve layouts with a choice of .842- (standard Chevrolet), .904-, .937-, or 1.063-inch-diameter lifters, with bushings for either standard tie-bar or keyed lifters. This is a good foundation for one very serious racing engine.

Dart also makes lightweight (140- pound) aluminum blocks that feature extra strengthening in critical areas, increased displacement capacity, true priority main oiling, and precision CNC machining. Dart’s Aluminum Big M block is a conventional Mark IV configuration that retains all production dimensions for compatibility with standard components. It is manufactured from virgin C355-T61 aerospace aluminum alloy and machined in-house to ensure absolute quality. Dart aluminum blocks feature ductile iron sleeves with extra-thick walls to promote excellent ring seal. Reinforcing ribs strengthen the lifter valley and bellhousing flange, and inboard head stud bosses provide additional head gasket sealing. The priority main oiling system delivers oil directly to the crankshaft bearings to enhance reliability at high engine speeds. These blocks include coated cam bearings, freeze plugs, and dowels.

Donovan Engineering
Donovan Engineering has been making aluminum racing engine blocks for more than 30 years, and each Donovan block is cast from strontium-modified B356 alloy with a special heat treat. These blocks may be ordered with full-water jackets, half-water jackets, or solid for drag racing use only.


Merlin III cast-iron blocks are available in 9.800- and 10.200-inch versions, and can be ordered with nodular iron or billet steel splayed-bolt main caps. All versions include priority main oiling, expanded water jackets for improved cooling of the siamesed bores, and .600-inch-thick decks with blind tapped bolt-holes. (Photo Courtesy World Products)


Cast from 357-A6 aluminum, Merlin X alloy blocks feature horizontal reinforcing ribs along the sides of the block and cross ribs in the lifter valley to stiffen the engine. (Photo Courtesy World Products)

The standard Donovan block weighs 140 pounds and is a traditional Mark IV replacement with oil filter and fuel pump bosses, standard motor mount and cam locations, and a custom 3/8-inch-wider oil pan rail. It is available in any deck height up to 10.300 inches, and with stock 4.840-inch bore spacing or custom 4.900- or 5.000-inch bore spacing. Chevy lifter bores (.842 inch) are standard, but any lifter bore diameter may be specified. For you marine types, you can even order the block anodized for corrosion resistance.

If you’re headed for the mountains, you can specify one of Donovan’s raised-cam blocks with options of .400- or 1.0-inch raised-cam location, 4.840- or 5.000-inch bore spacing, and deck heights up to 12.000 inches. These blocks all feature a 3/4-inch wider-than-stock oil pan rail to clear long strokes. Weight is up to 180 pounds, depending on the deck height and water jacket configuration desired.

Merlin (World Products)
As one of Bill Mitchell’s innovative companies, World Products has been producing its Merlin line of big-block Chevy engine blocks for years. They also follow the original Mark IV pattern in terms of parts fitment, and accept Mark IV spec cranks, heads, cams, oil pans, timing covers, etc. World’s current version of the Merlin block is the Merlin III, easily identified by the name cast in 1-inch-tall letters on the front of the block.


This 454 block has the last three digits of the casting number, 445, repeated on the block just above the oil filter mount, along with the date code K 2 1, plus the words “Hi Perf” and “PASS.” The “7.4” between the two freeze plug holes tell us it’s 454 (7.4 liters) with an original bore size of 4.250 inches. K 2 1 indicates that it was cast on November 2 in 1981 (K = November, 2 = day of the month, 1 = the last digit of the decade). How do you know it’s 1981 from the single digit “1”? In 1971 Chevy had not yet started using the metric designation 7.4, and by 1991 it would have been a Gen V block, which you can tell it’s not from the recessed oil filter boss and the 1-3/4-inch freeze plug bores. “Hi Perf” and “PASS” means it could be either a two- or four-bolt main block; you just have to look to see which one it is. Nearly all big-blocks have both Hi Perf and PASS cast into them, so ignore that.

Merlin III blocks are available in 9.800- and 10.200-inch (tall deck) versions, and can be ordered with nodular iron or billet steel splayed-bolt main caps. All versions include priority main oiling, expanded water jackets for improved cooling of the siamesed bores, and .600-inch-thick decks with blind tapped bolt-holes to prevent coolant leakage. The bottom end accepts standard Mark IV oil pans, and the crankcase has been clearanced to accept strokes up to 4.375 inches (up to 4.750 inches in the tall-deck blocks). The blocks are available in three bore sizes: 4.240, 4.490, and 4.590 inches, allowing you to finish hone the bores to your specs. Maximum bore size is 4.625 inches, and the minimum cylinder wall thickness is .240 inch at 4.600 inches.

World also sells its blocks fully raceprepped to your specifications, with finished bores and deck heights, cam bearings installed, etc., allowing you to do a fit-check and assemble the short block with no further machining required. Merlin blocks come with indexed stock location and diameter (.8437 inch) lifter bores. Approximate weight of these sturdy iron blocks is 270 pounds.

If an aluminum block is what you want, the Merlin X offers all the same features of the Merlin series in a 140-pound package. Cast from 357-A6 aluminum, these alloy blocks feature horizontal reinforcing ribs along the sides of the block and cross ribs in the lifter valley to stiffen the engine. Recommended maximum bore size is 4.600 inches, due to the use of cast-iron sleeves. The lubrication system features an integral boss for front-feed and a boss for rear scavenge. The rear main cap has provisions for a wet sump pump, and the block is also drilled for dry sump valley scavenge lines with cross-feed lines between left and right lifter oil galleries. The splayed-bolt main caps are made of 1045 alloy steel, attached with premium APR main studs and bolts.

Block Casting Dates
Big-block casting dates are generally located on the rear ledge of the block on the passenger side, although occasionally you find these dates on the driver’s side or even on the side of the block near the freeze plugs. The code is a simple alphanumeric code such as “C 12 7.” The first letter stands for the month of the year (A = January, B = February, etc.), so C would be March. The second numeral is the day of the month, and the last is the year of the decade. Which decade is not always clear, though it’s pretty easy to decipher for the big-block Chevy.

Early Mark IV–style big-blocks were not produced until 1965, and by 1975 they were only found in trucks. By the late 1970s, big-blocks had the displacement in liters cast into the sides of the block, for instance, 7.0 (427 ci), 7.4 (454 ci), or 8.2 (502 ci), so the decade your block was produced is usually pretty easy to decipher. Gen V blocks were only produced from 1991 through 1996, and Gen VI blocks from 1996 to 2000.

Going back to our mystery “C 12 7” code, the block was cast (not necessarily assembled until later) on March 12 of some year ending in “7.” If it were 1967, the block would accept an old-style canister oil filter housing, and might be a 396 (4.094-inch bore) or 427 (4.250-inch bore). If it were 1977, it would be 454 truck block with a 4.250-inch bore. By the 1980s, big-blocks had the engine size (in liters) cast into the side of the block, so a 1987 block from a truck would have “7.4” cast in. Simple, no?

Written by Tom Dufur and Posted with Permission of CarTechBooks
probably one of the most common problems I see over and over is some guy who reads through some magazine article,
that shows some group of guys who build a 600-900 hp engine,
what they skip over or ignore in that article would fill a couple books.
then to compound the problem further, the guy wanting to duplicate the articles engine build,
he looks at the components they used and says to himself....

I can,t afford those big dollar heads, or that forged stroker crank , or forged big dollar connecting rods, and forged high compression pistons,
and I already have a perfectly good 5 quart oil pan,
why should I spend $500 plus on a 8 quart oil pan, windage screen and oil system machine work,
or about any of that expensive detailed machine work, or a couple dozen other parts,
like, new higher ratio, roller rockers or new valve springs or a multi angle valve job,or port work on the ridiculously expensive new heads, they used?
and I already have a stock cast crank, or pistons and..
I just had my stock heads rebuilt last year,
so Ill just buy the cam and install it, after all, that is the key!
then they seem shocked when if it even runs its producing nowhere near the intended power

a general list of components commonly found in such an engine:

  1. Engine block (and main caps and bolts)
  2. Cylinder heads(head gaskets and bolts)
  3. Crankshaft
  4. Pistons
  5. rings for pistons (compression, second and oil rings)
  6. piston connecting rod pins
  7. cylinder head index dowels
  8. timing cover index dowels
  9. crank keyway
  10. oil filter
  11. oil pressure sensor
  12. crankshaft pilot bearing
  13. intake manifold thermostat
  14. block oil pressure sensor
  15. Connecting rods(including bolts)
  16. bearings (crank and rod)
  17. oil pump( plus mounting bolt)
  18. oil pump pick-up (remember to braze)
  19. BRASS freeze plugs (use sealant)
  20. oil passage plugs
  21. Camshaft (security plate and bolts)
  22. lifters
  23. push rods
  24. gaskets
  25. crank damper
  26. crank damper, washer and bolt
  27. timing chain
  28. timing chain cam and crank gears
  29. timing chain cover
  30. flexplate
  31. flex plate bolts
  32. pushrod guide plates
  33. rocker arms
  34. rocker arm adjustment nuts
  35. rocker arm studs
  36. valve covers
  37. valve cover bolts
  38. Valvetrain components (valves,spring shims, valve seals, springs,valve keepers,spring retainers)
  39. Intake manifold (gaskets and bolts)
  40. Exhaust headers (gaskets and bolts)
  41. Oil pan(gaskets and bolts)
  42. windage tray
  43. Water pump(gaskets and bolts)
  44. ignition wire and (ceramic spark plug boots)
  45. Spark plugs
  46. Fuel injectors
  47. Ignition system components
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read through this

do your research carefully and talk to your local machinist about you project before you start spending money on parts and machine work!
one factor I really hate about building seriously competitive engines, at a reasonable price is both the required research, and it is that uncontrollable fact, that once you build a really good and cost effective combo, you could safely bet your next 5 pay checks, that inside of a year several of the components you tested and found matched well and you found that worked perfectly in that combo,
are going to be manufacturer discontinued or the price will go up 30%-50% and the part will have been modified in several ways so its no longer compatible, or it no longer fits etc.
I know I built several SBC, BBC, and early 392 hemi engines where I carefully listed, documented and tested combos,
and you go to duplicate it, and its impressive results, a year or two later and 1/3rd of the components and at least one or two of the vendors or manufacturers have recently gone out of business or they say the components are no longer being made.
and of course you spent a good deal of time getting the local machinist in your local machine shop, to do the machine work correctly,, only now you find that the skilled machinist has retired or quite or died, or that machine shop closed!
then you kick yourself because you could have purchased major components you used last year in any reasonable quantity
at 1/2 or 2/3rds the current price , and even at the new higher price the parts offered are not the same quality, or they are on a 4-5 month back order...and if you paid for the part and wait the 4-5 months it really takes 6-7 months to arrive, but your patient, knowing you have a killer combo,
a well proven set of well matched parts.... only to find...after having waited even at the new higher price the parts offered are not the same quality,
or the manufacturer substituted some "improved" non-compatible part to fill your order, or he failed to even read the order correctly, and you listed specific details like a SCAT 4340 steel crank with a 4.5" stroke BBC crank assembly with 4.5" forged pistons and 6.535" connecting rods
and you get a mix of eagle, manely and a selection of some chinese copy's of the part's you ordered (like a cast vs a 4340 forged crank,) and some moron on the service desk phone, who even if you are totally polite and fax him a copy of the order with the details typed on it in large print, pointing out the pistons have the wrong pin or compression height or diameter for the bore size you listed, or the ring's got substituted , and they are not compatible with the pistons shipped.
who won't give a refund, because "its all the same parts you ordered" :swearing: :facepalm:
then of course its was ordered as a BALANCED rotating assembly and its obviously a random selection of mis matched parts your machinist must clearance and balance if its even useable,

best advice always order direct from SCAT, or BRODIX, AFR, CROWER, LUNATI, or at least JEGS AND SUMMIT, as they have a decent track record ,many of the less well known vendors advertising on EBAY, simply have parts dropped shipped, and have little reason to give a crap, as they have your money, and would not know the difference between a 348 crank and a 482 BBC crank if their lives depended on guessing correctly.
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