types of crankshaft steel


Staff member
when shopping for a rotating assembly , it pays too carefully compare features, read the fine print carefully ,and do some careful pre-purchase research.
price is NOT the most important consideration, value per dollar spent, quality and durability would be far higher on my list of concerns, or if I could make in clearer, if I found spending an additional $100-$200 would add significantly to the precision of the parts being used,or you could select parts made from a significantly better alloy Id certainly opt for spending a bit more cash to boost precision and durability.

bore diam x bore diam. x stroke length x # cylinders x .7854= displacement



When the counterweights alone can be made to balance the crankshaft, the crank is said to be "internally balanced". If the counterweights are too light by themselves to balance the crankshaft and more weight is needed, an "external balance" can be used.


Directions for crankshaft grinding and polishing
Crankshaft journal surfaces should be ground and polished to a surface finish of 15 micro inches roughness average Ra or better. Journals on highly loaded crankshafts such as diesel engines or high performance racing engines require a finish of 10 micro inches Ra or better.

The above is a simple straight forward specification which can be measured with special equipment. However, there is more to generating a ground and polished surface than just meeting the roughness specification. To prevent rapid, premature wear of the crankshaft bearings and to aid in the formation of an oil film, journal surfaces must be ground opposite to engine rotation and polished in the direction of rotation. This recommendation and examination of the following illustrations will help make the recommendation more clear.

Metal removal tends to raise burrs. This is true of nearly all metal removal processes. Different processes create different types of burrs. Grinding and polishing produces burrs that are so small that we can't see or feel them but they are there and can damage bearings if the shaft surface is not generated in the proper way. Rather than "burrs", let's call what results from grinding and polishing "microscopic fuzz." This better describes what is left by these processes. This microscopic fuzz has a grain or lay to it like the hair on a dog's back. Figure 1 is an illustration depicting the lay of this fuzz on a journal. (Note: All figures are viewed from nose end of crankshaft.)


The direction in which a grinding wheel or polishing belt passes over the journal surface will determine the lay of the micro fuzz.

In order to remove this fuzz from the surface, each successive operation should pass over the journal in the opposite direction so that the fuzz will be bent over backward and removed. Polishing in the same direction as grinding would not effectively remove this fuzz because it would merely lay down and then spring up again. Polishing must, therefore, be done opposite to grinding in order to improve the surface.

In order to arrive at how a shaft should be ground and polished, we must first determine the desired end result and then work backwards to establish how to achieve it. Figure 2 depicts a shaft turning in a bearing viewed from the front of a normal clockwise rotating engine. The desired condition is a journal with any fuzz left by the polishing operation oriented so it will lay down as the shaft passes over the bearing (Figure 2).


The analogy to the shaft passing over the bearing is like petting a dog from head to tail. A shaft polished in the opposite direction produces abrasion to the bearing which would be like petting a dog from tail to head. To generate a surface lay like that shown in Figure 2, the polishing belt must pass over the shaft surface as shown in Figure 3.


The direction of shaft rotation during polishing is not critical if a motorized belt type polisher is used because the belt runs much faster than the shaft. If a nutcracker-type polisher is used, then proper shaft rotation must be observed (Figure 4). Stock removal during polishing must not exceed .0002" on the diameter.


Having determined the desired surface lay from polishing, we must next establish the proper direction for grinding to produce a surface lay opposite to that resulting from polishing. Figure 5 shows the grinding wheel and shaft directions of rotation and surface lay for grinding when viewed from the front or nose end of the crankshaft. This orientation will be achieved by chucking the flywheel flange at the left side of the grinder (in the headstock). Achieving the best possible surface finish during grinding will reduce the stock removal necessary during polishing.


The surface lay generated by grinding would cause abrasion to the bearing surfaces if left unpolished. By polishing in the direction shown in either Figure 3 or 4, the surface lay is reversed by the polishing operation removing fuzz created by grinding and leaving a surface lay which will not abrade the bearing surface.

Nodular cast iron shafts are particularly difficult to grind and polish because of the structure of the iron. Nodular iron gets its name from the nodular form of the graphite in this material. Grinding opens graphite nodules located at the surface of the journal leaving ragged edges which will damage a bearing. Polishing in the proper direction will remove the ragged edges from these open nodules.

All of the above is based on normal clockwise engine rotation when viewed from the front of the engine. For crankshafts which rotate counterclockwise, such as some marine engines, the crankshaft should be chucked at its opposite end during grinding and polishing. This is the same as viewing the crank from the flanged end rather than the nose end in the accompanying figures.

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having used quite a few lathes and mills, while in engineering classes.
the thing that I noticed immediately,
while watching the video,
was the
lack of an expected flood of cutter lubricant,
and coolant, being used during the machining process




before you buy components talk to both the vendors and your machine shop of choice , you damn sure don,t want mis-matched components and clearances.
you need to measure accurately, know what your current block will function correctly with and pay attention to clearances and other details that make or break the engines potential durability and power potential.
Theres no direct interchangeability, but,you might want to have a long detailed discussion with your local performance machine shops, skilled machinist,
if you have access to a good skilled machinist and deep pockets you have options, the 348/409 cranks are similar in dimensions to the 396-427 BBC engines, if you wanted to stroke out a 348 or 409 the better machine shops can cut down the main bearing size on a 427-or-454 BBC crank down from its 2.75" diameter to fit a 2.5" journal size of the 348/409 blocks bearings, and if you wanted to go through the cost and trouble you could have the main crank journals welded up and then cut and polished too DE-stroke a BBC engines main journal bearing size.
obviously the options would require re balancing and clearance work.
all cranks must be , cleaned carefully, the oil passages cleaned carefully,checked for straightness and journal finish and bearing clearances carefully verified
and assemblies carefully balanced, and of course clearances to the block walls, lower cylinders and cam to rod
clearances checked , and rod lengths, piston pins, must match rods and pistons, piston compression heights, must be verified, and ring, bore size ,end gaps and ring thickness to fit piston grooves , with any non-original bore/stroke combos must be checked carefully





Engine Balance: Internal vs. External
An engine must be balanced to ensure smooth operation. It minimizes vibration and maximizes engine life. Balancing can be internal, external, or a combination of both.

Balancing an engine means offsetting the weight of the pistons and rods. This involves adding or removing weight from the crankshaft. The Harmonic Balancer and/or the flexplate or flywheel can also be weighted.

Internal Balance
An internally balanced engine has all the counterweight on the crank. External parts like the balancer and flexplate/flywheel have a neutral balance. They will not affect the other rotating parts.

External Balance
If the crank's counterweights are too light, the engine must be externally balanced. This involves adding weight to the harmonic balancer and/or the flexplate or flywheel.

How does it affect performance?
Generally speaking, internal balance is the better option. External counterweights can cause the crankshaft to flex at high rpm. This can cause engine damage. However, either type of balance is fine for most engines.

Converting from external to internal balance can be expensive. It requires a new crankshaft, harmonic balancer, and/or flywheel or flexplate. You may also need to clearance the block for the larger counterweights. Unless you're racing, it's easiest to balance the engine the same way the factory did.

Engine Type Factory Balance Method
Chevy 305/350 (2-piece rear main seal) Internal
Chevy 396-427 Big Blocks
Chevy LS Engines
Ford Modular Engines
Chevy 400/454 External
Ford 302/351W
Chevy 350 (1-piece rear main seal, including LT1) Combination of Internal & External

Balanced Rotating Assemblies come pre-balanced from the manufacturer. These can be installed without taking the parts to the machine shop.

If you buy an Unbalanced Rotating Kit, you will need to have it balanced before it's installed. The same is true if you buy a crankshaft, connecting rods, and pistons separately.

Crankshafts are listed as internal or external balance. This doesn't mean it's already balanced. It just tells you how it's intended to be balanced. It must be checked with the specific piston and rod combination you use.







these links may help








while the basic steel type used in a crank shaft is very important, the accuracy of the machine work, heat treatment and the care taken in surface prep,journal concentracy, surface smoothness and the balancing of the whole rotating assembly can be critical to durability
you may find this info useful, on CRANK SHAFT STRENGTH
MATERIAL....................TENSILE STRENGTH.....PSI.
CAST IRON.....................APROX 75,000
NODULAR IRON................APROX 95,000
CAST STEEL...................APROX 105,000

1053 forged....................APROX 97,000(can be heat treated higher)
5140 forged steel.............APROX 115,000
4130.forged.....................aprox 123,000
4340 forged.....................aprox 143,000




Ive placed both scat and eagle crank shafts next to a similar chevy OEM crank, and carefully examined all three and in my opinion the eagle crank was the least well finished with the scat crank being the best, now obviously all three manufacturers have made several grades of cranks and Ive used a truck load of SCAT and FORGED CHEVY crank shafts over the years with good results








Mallory metal
From Wikipedia, the free encyclopedia
Mallory metal is proprietary name[1] for an alloy of tungsten, with other metallic elements added to improve machining.

Its primary use is as a balance weight which is added to the crankshaft of an automotive engine, where the existing counterweight is not large enough to compensate for the weight of the reciprocating and rotating components attached to the crankshaft's connecting rod journals. Rather than add to the counterweight by welding or fabrication, holes are drilled in structurally safe positions in the counterweights, and "slugs" (cylindrical dowels) of Mallory metal are inserted and fastened securely.

The difference in density between the replacement Mallory metal and the original steel is about 2:1, so the counterweight is heavier without changing its shape or size.

stock crank?
cast iron?
cast steel, nodular iron,
5140 forged?
4340 forged?
that can cover a wide range, any idea as to the part number and keep in mind the block and main caps ,
limits how much rpm and torque to some extent before the main caps and main cap bolts start to distort,
but its valve train failures and connecting rods and connecting rod bolts that are the most common sources of failures,

FAILURES that frequently get ignored yet,those parts failing get BLAMED AS CRANK FAILURES.
Small Block Chevy Crankshaft Casting Numbers

Years Casting CID Material Journal Rmain Seal Applications

1968-73 1130 307,327 cast large two all
1968-76 1181 350 cast large two all
2680 327 steel small two
2690 350 steel two
1968-69 3279 302 forged large two Z-28
1962-67 4577 327 forged small two -
1968-73 4672 307,327 cast large two -
1975-85 310514 350 - large two -
330550 350 steel two
1975-76 354431 262 cast large two Monza,Nova
1955-67 3727449 265,283 forged small two -
3729449 265 steel two
1962-67 3734627 327 forged small two -
1955-67 3735236 265,283 forged small two -
1957-63 3735263 283 forged small two -
1962-67 3782680 327 forged small two -
3814671 327 steel small two
1955-67 3815822 265,283 forged small two -
1957-65 3835236 283 forged small two -
1956-63 3836266 265,283 forged small two -
1963-67 3849847 283 cast small two -
1964-67 3876764 283 cast small two -
1964-67 3876768 283 cast small two -
3884577 327 steel small two
1967-76 3892690 350 cast large two -
1968-73 3911001 307,327 cast large two -
3911011 307,327 cast large two
3914672 327 steel large two
3923279 302 steel large two
1969-85 3932442 305,350 cast large two in 1979-82 267
1968-73 3941174 307,327 cast large two -
1968-69 3941178 302 forged large two Z-28
1969-85 3941182 350 forged large two Z28, Vette,truck, some nitrided
3941188 350 steel two
1964-67 3949847 283 - small two
3951130 327 steel large two
1970-80 3951529 400 cast XL mns two 3.76" stroke, ext. bal.
1986-on 14088526 305,350 cast large one
1986-on 14088532 350 forged - one truck
1986-on 14088535 305,350 cast large one all
86-88 14088552 350 forged one








OBVIOUSLY a machine shop doing balancing work on a rotating assembly's , and adding mallory metal slugs to counter weights,on the crank must do quality work or problems with durability usually result that get damn expensive or dangerous

"5140 or 4340 ? Get the Facts and End the Confusion."

Before we can answer the question "which metal do I need in my crankshaft". I think we need to take a moment and review just what each metal is made of and what are the best applications for each. In the following discussion we will see the strengths and weaknesses of each and with this information we will be able to decide which Crankshaft material will best fit our needs. and keep in mind the longer the stroke, and the smaller the bearing journal diameter, and the smaller the counter weights are, the less structural strength is physically possible in the areas connecting the main bearing journals to the rod bearing journals, theres always a trade-off in weight and material strength and area cross section

Starting with the basics, metals containing primarily iron are classified as "ferrous metals". They range from pure iron through exotic high-alloy steels. Stock Crankshafts are made from cast iron, a metallic iron with more than 2 percent dissolved carbon. One preferred variation, ductile or nodular iron has all its carbon contained in the form of tiny spherical graphite nodules uniformly dispersed throughout the metal's matrix. This makes the material more ductile (deformable rather than brittle) and eases casting and machining.

Even the best cast iron has only limited tensile strength. Increasing ductility, hardness, malleability and fatigue resistance requires removing most carbon and at the high end, alloying iron with other elements, creating "steel" an iron with less than 2 percent carbon

The most basic form of this is carbon steel, which contains up to 1.7 percent carbon and minimal additional alloying elements. Carbon steels are designated by a four digit number. The first two digits indicate the basic type, and the last two digits indicate the approximate midpoint of the carbon content. The "10" ID's these alloys as non-resulfurized carbon steel with some manganese (popularly called medium-carbon or mild steel). The second two digits the "45" or "53" means the steel contains about 0.45 or 0.53 percent carbon respectively. Stock forged OEM cranks are usually made from 1045 or 1053 steel. There are exceptions to this, some 350 high performance steel cranks in the sixties were made from 5140 and some manufactures offer 5140 or 4340 in their high performance aftermarket catalogs.

From these mild OEM steels the next step up is Alloy steel. Alloy steels allow for more variations depending on the alloying materials. Over time as manufacturing techniques improved and chemical knowledge grew., metallurgist developed whole families of alloy steels, custom-tailored to make metals stronger, lighter, more durable, more ductile, and harder. Alloy steels are also identified by a four-digit number, with the first two digits indicating the major alloying element or elements, with the last two digits indicating the approximate midpoint of the carbon range.

We will now examine the four most common groups of steel, we will examine their best uses and hopefully come up with a buying criteria for making a decision on our crankshaft purchase. We want our purchase to be based on knowledge of the product and its intended use.

4130 The best known chrome-moly steel. It is a high-strength/high-stress alloy when produced in thin sections (sheet metal and tubing). But 4130 possesses very poor deep heat-treating characteristics which make it a bad choice for machined or forged parts.
------------------------- ------------------------- ------------------------- -----

4140 A deep-hardening chrome-moly steel , it forges well and has good impact resistance, fatigue strength and general all around toughness.
------------------------- ------------------------- ------------------------- -----

4340 A nickel-chrome-moly steel, this alloy is used to make premium cranks.4340 has good tensile strength, toughness, and fatigue resistance. Modified 4340 alloys with vanadium and more silicon can make this already good alloy even tougher and more fatigue-resistant. The main drawback is cost.
------------------------- ------------------------- ------------------------- -----

5140 This chromium alloy increases tensile strength, hardness, toughness, and wear-resistance over carbon steel. It has the same basic elements of 4340 and is made with the same process but is more affordable.
------------------------- ------------------------- ------------------------- -----

So what can we conclude from this short primer. Our first conclusion is that we don't want to purchase a crank made from 4130. The lack of deep heat treating properties makes it unacceptable for most performance applications. That leaves us with 5140 and 4340. Of the two we feel 5140 is the crankshaft material that suits most clients needs. Reason #1, based on feedback from clients using our cranks the 5140 crankshaft lasts as long as the 4340 when used in all but the most extreme racing conditions. For applications where the engine is putting out 800hp or less and turning 8,000rpm or less, 5140 is the right choice. Reason #2, in engine building you save money where ever you can, if it doesn't effect the performance or durability of the engine and our 5140 crankshafts are priced 30-40% below 4340 crankshafts in cost.

short answer,forged is best, cast steel is significantly stronger than plain cast iron and can be slightly more flexible, unfortunately, as the quality gets better the cost gets higher, and your connecting rods are FAR more likely to fail than the crank in most engine combos below about 6500rpm

As with most components you tend to get what you pay for to a great extent and companys like (CROWER, CARRILLO,and OLIVER will gladly provide you with much stronger AND MORE EXPENSIVE) connecting rods , good moderately priced connecting rods are available from SCAT







http://www.crankshaftco.com/steel-crank ... ening.html



http://www.popularhotrodding.com/tech/0 ... index.html


http://scatcrankshafts.com/scattechpdfs ... e_Nose.pdf

http://www.campbellenterprises.com/cran ... cranks.htm

http://www.flatlanderracing.com/.....look up (stroker kits)+ (corrillo rotating assemblies)

http://www.enginebuildermag.com/Article ... build.aspx

http://www.scribd.com/doc/11454996/How- ... Crankshaft

http://www.carcraft.com/techarticles/11 ... index.html

http://www.autosteel.org/AM/Template.cf ... NTID=33458

http://www.crankshaftco.com/steel-crank ... ening.html


http://www.steel.org/AM/Template.cfm?Se ... NTID=29408

http://books.google.com/books?id=TcN8Do ... q=&f=false

Ive used dozens of SCAT rotating assembly's
(mostly the 4340 forged versions) but a few 9000 cast and I have not had any major issues, but Id suggest selecting the 7/16" upgrade rod bolts and connecting rods and having the assembly balanced

Im using a scat forged 6" rod kit with a 4340 crank in my personal 383

judging from what Ive seen personally, looking at the import cranks
good quality

not quite as good but still acceptable

even lower quality , Id pass.
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"Tech Tips Provided by Andy Jensen

April 2005 Tech Tip: Crankshafts

This month I'd like to cover the part of your racing engine that makes it all happen. It takes the reciprocating motion of the pistons moving up and down in the cylinder and transforms it into rotating motion that can be used to turn the wheels. The crankshaft! First we'll cover what types of crankshaft materials are available and how to choose the right one for your application.

Beginning the list, because it's the most common and economical, is cast iron. This is the material that is found in most stock engines. A lot of guys will say that a cast iron crankshaft is no good for performance use, but with the right preparation these crankshafts will endure a lot of abuse.

For mild street use or stock rebuilds, all we do at the shop is magnaflux and regrind them. If a racer wants to use it for bracket racing or limited oval track use, we will remove all of the casting imperfections on the rod throws to eliminate stress risers (a place for cracks to start). We will also cross drill the oil holes to provide better rod bearing lubrication.
One of the most important things that we do to a cast iron crankshaft equipped engine is not done to the crankshaft. It is very important that we use rods and pistons that are as lightweight as possible, so they don't tear the rod journal off of the crank when it tried to stop them and pull them back down the cylinder at top dead center. With the right prep work and a lightweight rod and piston combination, a cast iron crankshaft should handle 500+ HP with no trouble at all.

Next, on the crankshaft ladder is a factory forged steel crankshaft. If one was made for your engine, the most common steel used is 1038. This is pretty much just plain old clean steel with some carbon added for heat treating purposes. A forged steel factory crankshaft is usually a good compromise of cost and strength, especially when purchased used. These crankshafts will hold up in more demanding applications than cast crankshafts, but still need some prep work before being used in racing applications. Again, the first thing we do is magnaflux it to make sure we don't spend time and money on a cracked crankshaft. Also, we remove the stress risers from the rod throws and cross drill the oil holes. Another option, especially attractive to circle track racers, is to drill the rod throws parallel to the crank axis with a ¾ or 7/8 hole. This makes the rod journal hollow and much lighter, with only a minimal loss in strength and it can be done for under $100.

The last thing we do before having the crankshaft reground is to have it shot peened. This also stress relieves the steel and makes a more stable crankshaft. A steel crankshaft prepared in this fashion will survive in all but the most demanding racing environments. A racer can choose what degree of crankshaft preparation best suits their application and budget.

At the top of the ladder are the aftermarket forged and billet steel crankshafts. There are many different manufacturers and price ranges. So how does the racer determine which way to go? First, I'll cover the most common materials available. There's 4130 and 4340 these numbers pop up all the time in crankshaft ads, but do we know what they mean?
I'll try to give a quick explanation. The last two numbers tell us how many 100ths of a percent of carbon is in the material. Carbon adds to the harden ability of the steel. 4130 will have 30% of carbon and 4340 will have 40% and so on. Both 4130 and 4340 start with a #4, this tells us that the steel is alloyed with molybdenum, or moly. This adds toughness to the steel. More moly means a tougher crankshaft. 4130 has 20% moly, while 4340 has 25%. In addition to more carbon and more moly, the 4340 is also alloyed with nickel, this is noted by the second number in the alloy. A nickel assures deep and uniform hardness in the crankshaft.

Clearly 4340 is the better material, but it does cost more. If you've reached the degree of performance that requires an aftermarket crankshaft, I can't see buying one of mediocre quality. Save your money and buy the top quality stuff, you'll be happier in the long run.
The next thing you should consider on a crankshaft purchase is how much it weighs. The lighter the crankshaft the more it will cost. Most company's start with the same forging for their standard and lightweight crankshafts, so if you're on a budget and can sacrifice the weight, the standard crankshaft is the way to go (as the strength and durability will be the same).

Well, that's about all the time I have this month. I hope this will help you spend your crankshaft dollars more wisely. Until next time, keep your right foot down. If you have an idea for a future tech tip, just email them to andy@jensensenginetech.com "
forged is always preferred on a performance build but if the cast cranks been checked carefully for cracks and the blocks mains are strait and you've got a decent lube system in place, 500hp-550hp on a cast big block crank and up to about 6000rpm seem to get along ok, cranks rarely fail, but they get blamed when bent valves or rods fail causing them to break,its usually, lubrication,issues, balance issues,clearances,rod bolt failures, detonation,damage, main caps, or valve control issues not crank strength in big block engine failures that cause problems, Id never worry about a cast BIG BLOCK CRANK under 6000rpm or 500hp-550hp, they seem to be well able to hold that stress level with zero problems.
Ive run several 454 and 496 engines with nitrous kits that worked for years with cast cranks as long as the balance, lube system, rods and ignition timing and valve control was not a problem, the cast BBC cranks take a significant amount of abuse, far more than ID suggest on a SBC cast crank.
its not the hp its the rpm,piston speed and the stresses on the block and crank that's generally the problem, we all know guys that have pushed cast cranks past the 500hp and 6000rpm limits I posted above and got away with it hundreds of times
a 3.76" stroke 427/396 can pull 6400rpm easily while a 454 can only pull 6000rpm at the same piston speed with even more rod angle.
yes you can push the limits and may get away with it for years, but stress is cumulative, the more you stress parts the faster they fail.
its the quality of the machine work and balancing plus attention to details like bearing clearances and the damper used that has a HUGE effect on durability , Ive built dozens of engines with SCAT cranks both CAST STEEL and 4340 FORGED STEEL, with ZERO issues the mere fact that there mention of needing excess force to spin the engine indicates MAJOR assembly issues.
the links posted go into most of the potential things that need to be checked BEFORE, and During the assembly process.
Even a forged 4340 crank will quickly fail if you don,t balance and assemble an engine with those factors set up correctly,and the FACT is that a forged steel or CAST STEEL crank is made of stronger material than a cast iron crank, thats not in dispute, its the engine builder thats responsible to make sure the clearance work, , parts selection,and balance work and parts matching process is correctly completed.
get cheap, assemble a random bunch of miss matched components , forget to do the clearance work, install a damper thats not correct and ANY crank assembly will eventually fail.
why do I say the BBC cranks tend to be stronger?
just larger stronger components, a cast sbc crank weights 50-57 lbs a cast bbc weights 67-69 lbs
that extra 10-19 lbs of cast steel adds strength
take the time to read thru these links theres a lot of good info
heres the catalog

Phone: 310 370 5501





keep in mind a few facts
and a crank thats flexing in the bearings tends to cause faster and more extensive bearing wear and main cap register issues more frequently.
while Ive always suggested use of ARP main studs the studs only increase the clamp loads and the cap strenght is not increased noticeably, if your going to put severe loads on a crank an aftermarket block with its thicker casting and better design, even splayed outer main cap bolts is a big help in maintaining bearing life



In any application where your tightening a nut on a stud , such as on the outer threaded ends of main cap studs or head bolt studs, youll want to use a lube on the threads that gives consistent torque reading from your torque wrench indicating the correct bolt or stud TENSION, oil and MOLY assembly lube and various thread sealants do not always do that,the end in the blocks course threads have thread sealant, the fine threads on the outer end require a totally different lubricant

Chevy V8 Crankshaft Journal Sizes
Here's a list of Chevy V-8 crankshaft journal sizes. All journal sizes are given in "STANDARD" sizes. Your crankshaft may have been cut down in size previously by a machine shop. Make sure your crank will work in the block you have. Blocks were made for each crank main journal size. If you are putting a "small" or "medium" journal smallblock crank into a "medium" or "large" journal smallblock block you will need crank bearing "spacers" or use special "thick" bearings available from aftermarket suppliers.

Chevy Smallblock V8 Crankshaft Journal Sizes

Gen.I, "Small Journal"

Gen.I, "Medium Journal", includes "Vortec" 305 and 350 thru '98

Gen.I, "Large Journal"

Non-production Gen.I combination, using Gen.I 400 crank in Gen.I 350 block
383...400 crank, Mains cut to 2.45"-Rods-2.10"

Non-production Gen.I combination, using Gen.I 350 crank in Gen.I 400 block
377..."Spacer" or "thick" main bearings with 350 crank-Rods-2.10"

Gen.II, "Medium Journal", includes "L-99" 265, "LT-1" 350, "LT-4" 350

Non-production Gen.II combination, using Gen.II 265 "L-99" crank in Gen.II 350 block

Gen.III, includes '97-2005 "LS-1" Corvette, Firebird, Camaro

Corvette "ZR-1", DOHC, "LT-5"

Chevy Big Block V8 Crankshaft Journal Sizes
ALL Chevy big blocks used...Mains-2.7488"-2.7495"---Rods-2.20"

Chevy 348-409 "W" Motor V8 Crankshaft Journal Sizes
427 "Z-11"
ALL "W" family motors used...Mains-2.50"-Rods-2.20"


if your using an INTERNALLY BALANCED crank and rotating assembly the damper and flywheel or flex-plate are at least in theory neutrally balanced and will have minimal effect on the total assembly, BUT if your crank and rods etc. are EXTERNALLY balanced I can,t see how the assembly CAN BE balanced without those components

related info






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My 468 big block Chev still has the # 7416 crank,its made from the 1053 forged material.Where does this stand as far as the tensile strength goes ???
http://gmperformancepartszone.com/crank ... -6236.html

http://paceperformance.com/index.asp?Pa ... odID=22912

http://www.mustangandfords.com/howto/29 ... index.html

http://books.google.com/books?id=Y98Smx ... el&f=false

http://books.google.com/books?id=N2XOAA ... q=&f=false




tensile strenght is in the 97,000 lb range,(can be heat treated higher) but IVE run those cranks in 700hp big blocks with out any problems and one link shows one in a 900hp turbo bbc without issues

Performance cranks for your LS6 or LS7.

These 454 c.i.d. and 502 c.i.d. forged steel crankshafts from GM Performance are designed for use in your LS-6 and LS-7 big-block V8s. Constructed of 1053 steel, they're nitride treated to increase hardness and fatigue strength. The main bearing journals are cross-drilled to provide a constant supply of oil to the rod bearings.
Crankshaft Selection Dictated by Design

All of the force generated from the explosion of the air/fuel mixture in the combustion chamber creates a force through the piston and rod, onto the journal of the crankshaft. The crankshaft turns this linear motion of the rods and pistons into rotary motion that propels the vehicle.

By Jim Walbolt

We like to think that inside a modern engine, for all the violent explosions and metal-straining power, a whole world of harmony can be found. Parts work together to produce the most power possible, races are won and trophies are captured.

Of course, this “cooperation” is a little deceptive. While there are dozens of parts that go into the building of any motor, and every part must work with every other part, some components inherently have a more important role than others. In essence, some parts are a little more equal than others.

The crankshaft is one of those parts. Everything that happens in an engine starts with the “crank.” It is the foundation or backbone of the engine.

All of the force generated from the explosion of the air/fuel mixture in the combustion chamber creates a force through the piston and rod, onto the journal of the crankshaft. The crankshaft turns this linear motion of the rods and pistons into rotary motion that propels the vehicle.

As you can imagine, the rod and piston are trying to shove the crank right out the bottom of the motor, so obviously, strength is a prime characteristic of a crankshaft. There are currently three types of manufacturing techniques used to make crankshafts – casting, forging and machining from solid billet. The type of crank that you use is directly dependent on the expected use of the part.

On the strength scale, cast iron crankshafts will fall the lowest. Manufacturing a cast crankshaft is simply a matter of pouring a molten metal into a mold. This has been the method OEMs have preferred for crankshaft manufacturing for many years. While I could quote you all kinds of numbers I will just mention a few. Most of you are engine builders, not metallurgists, and hey, even I don’t understand all the numbers! We’re just looking for results, right? And a lot of those results can be tied to strength.

The basic cast iron used for crankshaft production has a tensile strength of around 80,000 psi, but is rather brittle. Nodular iron is a slightly improved cast iron with a tensile strength of around 95,000 psi, but because of slightly higher carbon content, nodular iron has nearly twice the elongation characteristics of standard cast iron.

Crankshafts will actually flex and bend, so greater elongation properties will give the nodular iron crank increased fatigue resistance.

Cast steel is also used and can increase tensile strength to around 105,000 psi. Cast steel has greater carbon content than nodular iron so it has even better elongation characteristics. Many companies offer cast steel crankshafts as entry-level performance pieces. These cranks are great when used in the right application.

Some engine builders believe that a cast crank is fine for a performance street motor but should never be used in a racing application. In fact, that’s really not true: the rules may dictate that you use an OE crankshaft. And in the majority of cases, that means a cast crank. A cast crank is perfectly suitable in the right applications. A general rule of thumb for cast cranks would be a horsepower range of 300-500 depending on the type of casting.

Keep in mind that there are many factors involved in selecting the right crank and you need to rely on experience to guide you. So you can’t just use the crank that came out of that junkyard motor that you are building up into a race motor. The crank will need to be prepped before it can be used, and that means magnetic particle inspection in addition to numerous machining operations. Many times (read most), it will be cheaper to purchase an aftermarket crankshaft. Many performance part suppliers carry a complete line of them.

Forged steel crankshafts are the most popular choice for performance engines. These are strong and durable and can handle horsepower from a few hundred to 1,500-plus hp. Forged crankshafts come in a variety of materials starting with 1045 or 1053, commonly used by the OEs for their forged cranks. These crankshafts have a tensile strength of about 110,000 psi, which is not much more than a cast steel crank. However, they have an elongation of 22 percent, much higher than the 6 percent of the cast steel.

Next up are the 5140 materials with a tensile strength of 115,000 psi. A crankshaft made from 5140 chromium steel would make a good choice for someone looking for an economically priced forged crank. Top-of-the-line forged cranks are typically made from 4340 alloy with a tensile strength of around 145,000 psi.

At the very top, at least in terms of tensile strength, are the forged billet crankshafts at around 165,000 psi. While a forged crank starts as a chunk of steel that is forged into the proper shape, a billet crank is CNC-machined out of a chunk of forged steel. The steel that a billet crank starts from is much larger than that used for a forged crank and with the extensive machining, a billet crank will cost many times that of a forged crank.

There are arguments on both sides as to whether a forged or billet crank is better (ask ten experts and you will get ten answers). We are not going jump into the fray here, but we will talk a little about the pros and cons of each.
One of the traditionally weak points in a crankshaft is where the rod journal meets the web. The force exerted on the rod journal by the rod causes the web on either side of the journal to flex in and out. In a forged crank, the grain of the steel is flowed and condensed making it stronger and tougher. By design, the flow can be made to follow around these stress points, packing the grain tighter, giving these areas greater strength and fatigue resistance.

In a CNC’d billet crank, the grain of the metal will run parallel to the centerline of the crankshaft. If the grain converges at a stress point there is a greater possibility for a crack to develop. However, it is much easier to get special alloys in a billet material, giving the opportunity to manufacture a stronger, tougher crankshaft.

Another advantage to a billet crank is that you can create it to virtually any design specification. With a forged crankshaft you are limited to the tooling and die available. To introduce a new design in a forged crank you would need to develop new tooling and dies, an expensive proposition. With a billet crank, it’s just a matter of changing the CNC programming. If you are doing a lot of R&D work with the crankshaft, such as moving journals around, trying different overlaps and strokes, etc., billet would be the best way to go.

Again, there are pros and cons to forged and billet crankshafts and there are arguments on both sides. For the average racer, a forged crank will provide good service; you don’t need to go to the expense of billet.
It should be noted that at the top echelons of racing such as drag racing’s Top Fuel and Top Alcohol classes, and NASCAR Sprint Cup, most teams are utilizing billet crankshafts. However, I think this has more to do with the flexibility to easily customize and create one-off pieces than other factors. Keep in mind that these teams can afford the additional expense and they have the engineers and technicians who spend thousands of hours in R&D looking for the design that will give them an edge over the competition.

The quality of any particular crankshaft is also related to the quality of the metal being used. But remember that all 4340 steel, for instance, is not the same. The percentages and mixtures used are proprietary to the top manufacturers and they constantly test the steel they use in manufacturing their crankshafts. It isn’t uncommon for a batch of steel to come in that is not within specifications. Buying from the top manufacturers will assure you of getting a quality part.



DAMAGE LIKE THIS IS far MORE FREQUENT WITH cast CRANKS AND ITS FREQUENTLY THE RESULT OF A DAMAGED OR DEFECTIVE BALANCER OR DAMPER! the reason its usually the front two cylinders or front of the crank that fails is because its that front counter weight and crank journal that absorbs the highest amplitude harmonic stress.
so be darn sure you replace the damper and have the new rotating assembly balanced correctly.

The American Society for Metals oversees the grading of metals, and for 4340 a range of different elements is allowed with the chemical data as follows:

Carbon 0.38-0.43 percent
Chromium 0.7-0.9 percent
Manganese 0.6-0.8 percent
Molybdenum 0.2-0.3 percent
Nickel 1.65-2 percent
Phosphorus 0.035 percent max
Silicon 0.15-0.3 percent
Sulphur 0.04 percent max
Iron Balance of material

The difference in quality among the top manufacturers is insignificant. Your choice will more likely depend on other factors, such as design, availability and customer service. As with any other part of your business, you will build a rapport with your supplier that works for you. Your supplier will be invaluable to you in the selection of the proper part for the application and can also assist you in creating your own proprietary designs if that is your cup of tea.

Crankshaft selection depends on many factors including rules, horsepower, rpm range, and whether the engine is naturally aspirated, turbo-charged, or supercharged. Supercharging, and to a lesser extent, turbocharging put a tremendous amount of stress on the bottom end of the engine. Again, your supplier can be a great help in the selection process.

Crankshafts are so good today, that if you choose the proper one for your application, it’s very unlikely that one will fail. Unless you used a cast crank in a nitro burning top fuel dragster, most crankshaft failures are actually the result of another problem in the engine. Just because the crank broke, don’t assume it was the crank’s fault: look for other reasons.

As an example, consider this story about a sprint car racer who broke two cranks in two weeks. The cranks broke at the front, which, by the way, is the most common area of breakage for crankshafts. He checked all kinds of things at the front of the engine, but couldn’t find a problem. He was ready to blame the breakage on a couple of bad crankshafts when he discovered the real culprit.

As most of you probably know, a sprint car is direct drive and the drive shaft is bolted directly to the back of the crankshaft. It turned out that the flange that attached the drive shaft to the crank had been machined slightly off-center. This caused a harmonic imbalance to develop at the front of the crank, causing it to fail.

Regardless of how good a fuel system you use, how good a tune-up you put on the engine, how good an ignition system, or for that matter, whether you use the best parts available or not, there is a point in any engine that it becomes unstable. The engine may run great – nice and smooth to a certain rpm – then it’ll run a little rough and you’ll feel that as a vibration. Once the engine passes that point it may smooth out again and be fine.

Some people believe that short tracks are harder on a crankshaft than a super speedway. Just the opposite is true in many cases. On a short track, an engine may not spend any time at that unstable rpm since you are on and off the throttle more. However, on a big track, the engine may spend more time at the critical rpm. Knowing where that point is can help extend the life of your crankshaft. If the engine spends a lot of its time at that point, failure will be much more likely.

Choosing the proper crankshaft depends on a host of factors, and each of them should be considered. Choosing a crank that is not strong enough for a particular application is as much a waste of money as choosing one that is stronger than needed.

why cast cranks and high stress and rpm are a bad idea





DAMAGE LIKE THIS IS far MORE FREQUENT WITH cast CRANKS AND ITS FREQUENTLY THE RESULT OF A DAMAGED OR DEFECTIVE BALANCER OR DAMPER! the reason its usually the front two cylinders or front of the crank that fails is because its that front counter weight and crank journal that absorbs the highest amplitude harmonic stress.
so be darn sure you replace the damper and have the new rotating assembly balanced correctly.
OEM SBC BLOCKS , are NOT as strong as the THICKER AFTERMARKET BLOCKS, and should NOT be used if your goal exceeds about 550 HP



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Small Block Chevy Crankshafts
Small block chevy crankshaft The 400 engines that were made from 1970 to ’80
used larger diameter crank main journals (2.65") and
the same rod journal size as medium journal cranks
(2.10"), but with a crank stroke of 3.76". These cranks
require external balancing by using specific vibration
dampers, flywheels or flexplates in the 400 motor.
This is also true if you build a popular non-factory
combination: a 400 crank with the main journals cut
down to 2.45" in a 350 block.
You must use the externally balanced 400 damper and 400 flywheel or flexplate. It is possible to
internally balance a 400 crank by having an experienced machine shop add heavy metal slugs to the
counterweights. Do not use an externally balanced 400 damper, flywheel or flexplate on an internally
balanced motor. I bring this up because on a number of occasions, folks have shown up at my shop
with a running 350 smallblock that had a huge vibration or a newly rebuilt 350 that had broken some
rods or suffered some other major disaster. When we checked the motor, I noticed that the 350
engine had a 400 vibration damper or a 400 flywheel or flexplate. The owners didn’t know the
difference, and they had unknowingly pulled a tired 400 motor out of the vehicle, replaced it with a
rebuilt 350, and used the 400 damper and flexplate on the new internally balanced 350 motor. It
doesn’t work for long.
A forged 350 steel crankshaft Rear flange of a crankshaft for use with a two piece rear main seal

A forged 350 steel crank (Casting
#-3941182) has casting numbers on the
front counterweight. However, only two digits
(41) are discernable here.
Shown are the rear flange and journals of a
Gen I crank that uses a two-piece rear main

In 1986, Chevy introduced the one-piece rear main oil seal and made related changes in cranks, oil
pans, gaskets and blocks. The medium journal cranks, used in one-piece seal blocks, are all
externally balanced and require the use of matching 1986 or later flywheels and flexplates. The flange
on the rear of the new style cranks was changed to fit the one-piece seals, and the bolt pattern for
flywheels and flexplates was reduced to a 3" diameter from the 3.58" bolt pattern used on two-piece
seal cranks from ’55 through ’85.

Cranks were balanced with whatever size motor and related rotating components it received at the
factory. A 307 crank is not balanced the same as a medium journal 327 crank, even though they
physically interchange with each other and have the same stroke. If you mix and interchange rotating
parts from different engines, have the rotating assembly rebalanced. Some cast, 2.45" main journal,
3.48" stroke, two-piece cranks have the same casting number (3932442), but are balanced
differently. Cast cranks used on 267, 305 and 350 motors should not be interchanged from one
engine size to another because of possible balancing problems, even though they have the same
stroke and will physically interchange in medium journal blocks.
The 1997 and later Gen. III cranks should be easy to spot once they become more available. The
main thrust bearing is on the middle #-3 crank journal, instead of on the #-5 rear journal as it is on the
Gen. I and II cranks.
Rear of crankshaft for use with a one piece rear main
This is the one-piece rear main
seal crank, which first came into
use in 1986 on all production
motors. Compare the rear flange
area to the earlier Gen. I two-piece
rear main seal crank.

(PN-3932444) is a nodular cast-iron 350 Gen. I crank with a 3.48" stroke. This crank is used with a
two-piece rear main oil seal and has 2.45"/2.10" journals.

(PN-366280) is a raw 5140 alloy forging used to build large journal cranks of various journal sizes and
strokes. This crank is no longer available from Chevy; it has been replaced by a forged raw crank
(PN-24502460). Use with a two-piece seal.

(PN-3941180) (Casting #-1182) is a 1053 forged steel crank, with a 3.48" stroke and 2.45"/2.10"
journals, not nitrided. This crank is used with a two-piece seal.
(PN-3941184) This is the same as (PN-3941180), but nitrided; 1182 casting number.
(PN-10185100) Same as (PN-3941184), but it is a raw forging of S38 alloy and it can be machined for
3.46" to 3.5" stroke length.

(PN-10051168) is a 4340 alloy, raw, non-twist forging, 3.20" to 4.0" strokes possible. It comes with
2.900" unmachined journals that can be cut to fit 400 smallblock 2.65" main journals. Use with a
two-piece seal.

(PN-3951527) is a cast 400 crank, 3.75" stroke, 2.65"/2.10" journals, ductile iron. Use with a two-piece
oil seal. It requires external balancing by using an appropriate 400 front damper and 400 flywheel or
(PN-24502460) is a raw forging of 4340 alloy steel that is similar to the raw forging (PN-10051168),
but it has additional material on the crank snout that can be machined to a larger diameter for use
with bigblock Chevy vibration dampers.This crank uses the two-piece rear seal.
Some crank surface treatments, such as nitriding, only penetrate the surface of the metal a few
thousandths of an inch. If the crank journals are later cut or reground, the treated surface may be cut
or ground off and the crank will have to be retreated. Some aftermarket crank makers use a
hardening treatment that penetrates .010" to .015" and will still be there after a reduction in journal
diameter of .010".
A cast crankshaft with its thin casting line Wide parting serface found on forged crankshafts

A cast crank can be distinguished from a
forged crank by its thinner parting line.
A thick parting line is seen on this 350 forged

One-Piece Rear Seal Cranks
All 1986 and later one-piece rear main oil seal cranks are externally balanced, have medium sized
journals and have a smaller bolt circle (3.0") pattern on the rear crank flange. This requires the use of
matching late-model flywheels and flexplates, which have mounting bolt hole patterns that match the
cranks for one-piece rear main seal engines. Flywheels and flexplates for two-piece rear main seal
cranks do not interchange with one-piece seal cranks.

Gen. III engines use cast cranks with rolled fillets and have a different firing order. These cranks have
2.558" main and 2.1" rod journals. The thrust is on the #-3 main bearing. In addition, the Gen. III uses
a front-mounted gerotor oil pump that is driven by a gear on the Gen. III crank snout. Consequently,
these Gen. III cranks are not interchangeable with previous smallblocks.
(PN-14088527) is a nodular cast-iron crankshaft for use with a one-piece rear main seal. This is a
3.48" stroke crank with 2.45" and 2.10" journals.

(PN-14096036) is a 1053 alloy forged crank with 2.45"/2.10" journals, 3.48" stroke. Requires a
one-piece rear main oil seal. The ZZZ, ZZ1 and ZZ2 350 HO crate motors received this crank.
(PN-14088533) is a 1053 alloy forged crank with 2.45"/2.10" journals, 3.48" stroke. Requires
one-piece rear main oil seal. This crank is used on the ZZ3 and ZZ4 crate motors and on the ZZ3
short-block partial assembly.
Used Cranks
When you are looking at a used smallblock crank, determine if it is a cast or forged crank. You can
expect to pay more for a forged one. The cast crank has a thin parting line on its throw arms. The
forged crank has a much thicker or wider parting line.

Check the casting number and casting dates to determine what stroke it is. Does it use a one-piece or
two-piece rear main oil seal? Measure the rod and main journals. Has the crank been previously cut
down? Machine shops that recondition cranks usually stamp the amount they have cut the crank on
the front crank throw arm. If your measurements show that the crank journals have been previously
cut more than 0.010", walk away. You can find another one.
Are the threaded holes in the rear flange stripped? Has the drilled hole for the pilot bearing at the
rear of the crank been elongated or damaged? Has the thrust surface on the crank been worn or
damaged? How about the threaded hole in the crank front snout? Some early crank snouts are not
drilled or tapped for a vibration damper retention bolt. You can get the snout tapped and threaded for
the bolt at a machine shop. Also, some early cranks that were used in automatic transmission cars did
not have a hole drilled in the rear of the crank for a manual transmission pilot bushing.

Remember, when you get the crank to the machine shop, ask the crew to clean it, checked for cracks
and straightness, clean out the threaded holes and oil passages, and possibly have it ground and
micro-polished. If any of the journals have been damaged, you may be able to have the journal
welded or chromed, then cut back to acceptable size. However, you need to compare the cost of fixing
a damaged crank to the cost of buying an undamaged one. At some point, it’s cheaper and easier to
find an undamaged used crank or buy a new one.
Cast Versus Forged Cranks
Chevy stock cranks are either nodular cast-iron or forged steel. To figure out which yours is, check
the parting line, which is left from the molds when the crank is poured. A cast crank has a thin parting
line, while a forged crank line is thicker or wider. Tap a crank lightly with something hard, and a cast
crank will emit a thudding noise. A forged crank rings like a bell; it is a quite distinctive sound. Of
course, you can also check the casting number.

Some people who build high-performance motors believe that they must have a forged crank and that
cast cranks just don’t cut the mustard. They would rather shell out the extra money for a forged crank.

The truth of this belief depends on your situation. Up to a point, cast cranks are fine. In a short-
duration, bracket drag race engine, 450 genuine horsepower is around the upper limit for a
smallblock cast crank. Almost any street application, short of insanity, can get along just fine with a
cast crank. At horsepower levels higher than 450, or if you are planning a nitrous or high-boost
blower or turbo applications, move to a forged steel crank. Good used cast cranks are more
numerous and less expensive than cast cranks. You can take the money you saved and spend it on
something else. Just be sure the crank is magnafluxed and properly prepped and use a high-quality
vibration damper (especially with a cast crank). Good things will happen.
These days, a large number of forged cranks are available from aftermarket suppliers for a large
range of applications, stroke lengths, steel alloys (most use a very strong 4340 alloy) and total
weights. These aftermarket cranks can also be prepared in various ways.
measuring a crankshaft with micrometers
Check the crank journal
diameters to see if the crank has
been previously cut and to
determine the size of the
bearings you need.

Chevy Big Block 454 Early/Late
CI Crank Rod Crank Stroke Rod Length Piston Piston Bore Type 112CC 118CC 124CC Unbal Complete

Chevy Big Block Series 9000
Cast Stock Replacement Street & Strip Rotating Assemblies

Series 9000 Cast Cranks, Pro Comp I-Beam Connecting Rods with 7/16" Cap Screws, Pistons

460 9-10454 2-ICR6135-7/16 4.000" 6.135" HYPER 4.280 FLAT 8.9 8.4 8.2 1-92249 1-92249BE
460 9-10454 2-ICR6135-7/16 4.000" 6.135" FORGED 4.280 FLAT 8.9 8.4 8.2 1-92250 1-92250BE
460 9-10454 2-ICR6135-7/16 4.000" 6.135" HYPER 4.280 DOME 13.7 12.8 11.9 1-92254 1-92254BE
460 9-10454 2-ICR6135-7/16 4.000" 6.135" FORGED 4.280 DOME 13.7 12.8 11.9 1-92256 1-92256BE
460 9-10454 2-ICR6385-7/16 4.000" 6.385" FORGED 4.280 FLAT 8.9 8.4 8.2 1-92260 1-92260BE
460 9-10454 2-ICR6385-7/16 4.000" 6.385" FORGED 4.280 DOME 14.0 12.7 11.7 1-92263 1-92263BE
489 9-454-4250-6135 2-ICR6135-7/16 4.250" 6.135" FORGED 4.280 FLAT 9.4 9.0 8.6 1-91350 1-91350BE
489 9-454-4250-6135 2-ICR6135-7/16 4.250" 6.135" PREMIUM 4.280 FLAT 9.4 9.0 8.6 1-91360 1-91360BE
489 9-454-4250-6135 2-ICR6135-7/16 4.250" 6.135" PREMIUM 4.280 DOME 10.5 10.1 9.5 1-91460 1-91460BE

Series 9000 Cast Cranks, Pro Comp I-BeamConnecting Rods with 7/16" Cap Screws, Pistons

489 9-454-4250-6385 2-ICR6385-7/16 4.250" 6.385" FORGED 4.280 FLAT 9.4 9.0 8.6 1-91505 1-91505BI
489 9-454-4250-6385 2-ICR6385-7/16 4.250" 6.385" PREMIUM 4.280 FLAT 9.4 9.0 8.6 1-91510 1-91510BI
489 9-454-4250-6385 2-ICR6385-7/16 4.250" 6.385" FORGED 4.280 DOME 10.7 10.2 9.7 1-91605 1-91605BI
489 9-454-4250-6385 2-ICR6385-7/16 4.250" 6.385" PREMIUM 4.280 DOME 10.7 10.2 9.7 1-91610 1-91610BI

Chevy Big Block 4340 Forged
Competition Rotating Assemblies

4340 Forged Standard Weight Cranks, Pro-Comp H-Beam Connecting Rods
with 7/16" Cap Screws, Forged Pistons, Rod Bearings, Main Bearings & Rings

460 4-454-4000-6135 2-454-6135-2200 4.000" 6.135" FORGED 4.280 FLAT 8.9 8.4 8.2 1-42005 1-42005BE
460 4-454-4000-6135 2-454-6135-2200 4.000" 6.135" FORGED 4.280 DOME 13.7 12.8 11.9 1-42055 1-42055BE
489 4-454-4250-6135 2-454-6135-2200 4.250" 6.135" FORGED 4.280 FLAT 9.4 9.3 8.6 1-42255 1-42255BE
489 4-454-4250-6135 2-454-6135-2200 4.250" 6.135" PREMIUM 4.280 FLAT 9.4 9.3 8.6 1-42257 1-42257BE
489 4-454-4250-6135 2-454-6135-2200 4.250" 6.135" PREMIUM 4.280 DOME 10.5 10.0 9.5 1-42260 1-42260BE

4340 Forged Standard Weight Cranks, H-Beam Connecting Rods
with 7/16" Cap Screws, Forged or PREMIUM Pistons

460 4-454-4000-6385 2-454-6385-2200 4.000" 6.385" FORGED 4.280 FLAT 8.9 8.4 8.2 1-42105 1-42105BI
460 4-454-4000-6385 2-454-6385-2200 4.000" 6.385" FORGED 4.280 DOME 13.7 12.8 11.9 1-42159 1-42159BI
489 4-454-4250-6385 2-454-6385-2200 4.250" 6.385" FORGED 4.280 FLAT 9.4 9.0 8.6 1-42305 1-42305BI
489 4-454-4250-6385 2-454-6385-2200 4.250" 6.385" PREMIUM 4.280 FLAT 9.4 9.0 8.6 1-42310 1-42310BI
489 4-454-4250-6385 2-454-6385-2200 4.250" 6.385" FORGED 4.280 DOME 10.8 10.2 9.7 1-42355 1-42355BI
489 4-454-4250-6385 2-454-6385-2200 4.250" 6.385" PREMIUM 4.280 DOME 10.7 10.2 9.7 1-42360 1-42360BI

4340 Forged Standard Weight Cranks, H-Beam Connecting Rods
with 7/16" Cap Screws, PREMIUM Pistons

540 4-454-4250-6385 2-454-6385-2200 4.250" 6.385" PREMIUM 4.500 FLAT 9.8 9.4 9.0 1-42370 1-42370BI
540 4-454-4250-6385 2-454-6385-2200 4.250" 6.385" PREMIUM 4.500 DISH 8.7 8.4 8.2 1-42375 1-42375BI
540 4-454-4250-6385 2-454-6385-2200 4.250" 6.385" PREMIUM 4.500 DOME 14.8 13.5 12.3 1-42380 1-42380BI
510 4-454-4375-6385 2-ICR6385-7/16 4.375" 6.385" PREMIUM 4.310 FLAT 9.1 8.7 8.4 1-42382 1-42382BI
510 4-454-4375-6385 2-ICR6385-7/16 4.375" 6.385" PREMIUM 4.310 DOME 14.8 13.5 13.3 1-42383 1-42383BI

4340 Forged Standard Weight Cranks, Pro Comp H-Beam Connecting Rods
with 7/16" Cap Screws, PREMIUM Pistons
10.200 TALL DECK

572 4-454-4500-6535 2-454-6535-2200 4.500" 6.535" PREMIUM 4.500 FLAT 10.0 9.7 9.4 1-42385 1-42385BI
572 4-454-4500-6535 2-454-6535-2200 4.500" 6.535" PREMIUM 4.500 DISH 8.8 8.5 8.2 1-42390 1-42390BI
572 4-454-4500-6535 2-454-6700-2200 4.500" 6.700" PREMIUM 4.500 DOME 15.3 14.3 13.5 1-42392 1-42392BI
572 4-454-4500-6535 2-454-6700-2200 4.500" 6.700" PREMIUM 4.500 FLAT 10.0 9.7 9.4 1-42395 1-42395BI
572 4-454-4500-6535 2-454-6700-2200 4.500" 6.700" PREMIUM 4.500 DOME 15.5 13.1 12.2 1-42397 1-42397BI

CI Crank Rod Crank Stroke Rod Length Piston Piston Bore Type 112CC 118CC 124CC Unbal Complete
4340 Forged Standard Weight Cranks with Center Counterweights, Pro Comp H-Beam Connecting Rods
with 7/16" Cap Screws, Premium Forged Pistons
10.200 TALL DECK

572 4-454-4500-6535-C 2-454-6535-2200 4.500" 6.535" PREMIUM 4.500 FLAT 10.2 9.6 9.2 1-43271 1-43271BI
572 4-454-4500-6535-C 2-454-6535-2200 4.500" 6.535" PREMIUM 4.500 DISH 8.6 8.3 8.7 1-43276 1-43276BI
572 4-454-4500-6535-C 2-454-6535-2200 4.500" 6.535" PREMIUM 4.500 DOME 12.5 11.8 11.3 1-43277 1-43277BI
572 4-454-4500-6535-C 2-454-6535-2200 4.500" 6.535" PREMIUM 4.500 FLAT 10.2 9.6 9.2 1-43278 1-43278BI
572 4-454-4500-6535-C 2-454-6535-2200 4.500" 6.535" PREMIUM 4.500 DISH 8.6 8.3 8.7 1-43279 1-43279BI
572 4-454-4500-6535-C 2-454-6535-2200 4.500" 6.535" PREMIUM 4.500 DOME 12.5 11.8 11.3 1-43284 1-43284BI
632 4-454-4750-6700-C 2-454-6700-2200 4.750" 6.700" PREMIUM 4.600 FLAT 11.4 10.6 10.2 1-43281 1-43281BI
632 4-454-4750-6700-C 2-454-6700-2200 4.750" 6.700" PREMIUM 4.600 DOME 13.9 13.2 10.2 1-43285 1-43285BI

CI Crank Rod Crank Stroke Rod Length Piston Piston Bore Type 112CC 118CC 124CC Unbal Complete

9000 Cast Street & Strip Rotating Assemblies

Series 9000 Cast Cranks, Pro Comp I-Beam Connecting Rods
with 7/16" Cap Screws Hypereutectic, Forged or PREMIUM Pistons

460 9-10454L 2-ICR6135-7/16 4.000" 6.135" HYPER 4.280 FLAT 8.9 8.4 8.2 1-92399 1-92399BE
460 9-10454L 2-ICR6135-7/16 4.000" 6.135" FORGED 4.280 FLAT 8.9 8.4 8.2 1-92400 1-92400BE
460 9-10454L 2-ICR6135-7/16 4.000" 6.135" HYPER 4.280 DOME 13.7 12.8 11.9 1-92404 1-92404BE
460 9-10454L 2-ICR6135-7/16 4.000" 6.135" FORGED 4.280 DOME 13.7 12.8 11.9 1-92406 1-92406BE
460 9-10454L 2-ICR6385-7/16 4.000" 6.385" FORGED 4.280 FLAT 8.9 8.4 8.2 1-92410 1-92410BE
460 9-10454L 2-ICR6385-7/16 4.000" 6.385" FORGED 4.280 DOME 14.0 12.7 11.7 1-92414 1-92414BE
489 9-454-4250-6135-L 2-ICR6135-7/16 4.250" 6.135" FORGED 4.280 FLAT 9.4 9.0 8.6 1-91650 1-91650BE
489 9-454-4250-6135-L 2-ICR6135-7/16 4.250" 6.135" PREMIUM 4.280 FLAT 9.4 9.0 8.6 1-91655 1-91655BE
489 9-454-4250-6135-L 2-ICR6135-7/16 4.250" 6.135" PREMIUM 4.280 DOME 10.5 10.0 9.5 1-91710 1-91710BE

Series 9000 Cast Cranks, Pro Comp I-Beam Connecting Rods
with 7/16" Cap Screws Forged or PREMIUM Pistons

489 9-454-4250-6385-L 2-ICR6385-7/16 4.250" 6.385" FORGED 4.280 FLAT 8.7 8.4 8.0 1-91755 1-91755BE
489 9-454-4250-6385-L 2-ICR6385-7/16 4.250" 6.385" PREMIUM 4.280 FLAT 9.4 9.0 8.6 1-91760 1-91760BE
489 9-454-4250-6385-L 2-ICR6385-7/16 4.250" 6.385" FORGED 4.280 DOME 10.5 10.0 9.5 1-91805 1-91805BE
489 9-454-4250-6385-L 2-ICR6385-7/16 4.250" 6.385" PREMIUM 4.280 DOME 10.7 10.2 9.7 1-91810 1-91810BE
540 9-454-4250-6385-L 2-ICR6385-7/16 4.250" 6.385" PREMIUM 4.500 FLAT 10.2 9.8 9.4 1-91900 1-91900BE
540 9-454-4250-6385-L 2-ICR6385-7/16 4.250" 6.385" PREMIUM 4.500 DISH 9.8 9.4 9.0 1-91905 1-91905BE
540 9-454-4250-6385-L 2-ICR6385-7/16 4.250" 6.385" PREMIUM 4.500 DOME 10.8 10.3 9.9 1-91910 1-91910BE


4340 Forged Standard Weight Cranks, H-Beam Connecting Rods
with 7/16" Cap Screws Forged or PREMIUM Pistons

460 4-454-4000-6135-L 2-454-6135-2200 4.000" 6.135" FORGED 4.280 FLAT 9.4 9.3 8.6 1-42445 1-42445BE
460 4-454-4000-6135-L 2-454-6135-2200 4.000" 6.135" FORGED 4.280 DOME 10.5 10.0 9.5 1-42446 1-42446BE
489 4-454-4250-6135-L 2-454-6135-2200 4.250" 6.135" FORGED 4.280 FLAT 9.4 9.3 8.6 1-42450 1-42450BE
489 4-454-4250-6135-L 2-454-6135-2200 4.250" 6.135" PREMIUM 4.280 FLAT 9.4 9.3 8.6 1-42452 1-42452BE
489 4-454-4250-6135-L 2-454-6135-2200 4.250" 6.135" PREMIUM 4.280 DOME 10.5 10.0 9.5 1-42454 1-42454BE

4340 Forged Standard Weight Cranks, H-Beam Connecting Rods
with 7/16" Cap Screws Forged or PREMIUM Pistons

489 4-454-4250-6385-L 2-454-6385-2200 4.250" 6.385" FORGED 4.280 FLAT 8.7 8.4 8.0 1-42405 1-42405BI
489 4-454-4250-6385-L 2-454-6385-2200 4.250" 6.385" PREMIUM 4.280 FLAT 9.4 9.0 8.6 1-42410 1-42410BI
489 4-454-4250-6385-L 2-454-6385-2200 4.250" 6.385" FORGED 4.280 DOME 10.5 10.0 9.5 1-42455 1-42455BI
489 4-454-4250-6385-L 2-454-6385-2200 4.250" 6.385" PREMIUM 4.280 DOME 10.7 10.2 9.7 1-42460 1-42460BI

4340 Forged Standard Weight Cranks, H-Beam Connecting Rods


Casting Number CID Years Journals Stroke Comments
1130 307/327 68-73 2.45/2.10 3.25 Nodular Iron
1178 302 2.45/2.10 3.00 Forged
1181 305/350 68-76 2.45/2.10 3.48 Nodular Iron
1182 350 2.45/2.10 3.48 Forged
2680 327 2.30/2.00 3.25 Forged
2690 350 2.45/2.10 3.48 Forged
3279 302 68-69 2.45/2.10 3.00 Forged
4577 327 62-67 2.3/2.0 3.25 Nodular Iron
4672 307/327 68-73 2.45/2.10 3.25 Nodular Iron
310514 350 77-85 2.45/2.10 3.48 Nodular Iron
330550 350 73-75 2.45/2.10 3.48 Forged
354431 262 75-76 2.45/2.10 3.1 Nodular Iron
3727449 283 57-67 2.3/2.0 3.00 Forged
3729449 265 55-57 2.3/2.0 3.00 Forged
3734627 327 62-67 2.3/2.0 3.00 Forged
3735236 265/283 55-67 2.3/2.0 3.00 Forged
3735263 283 57-63 2.3/2.0 3.00 Forged
3782680 327 62-67 2.3/2.0 3.25 Forged
3814671 327 2.30/2.00 3.25 Forged
3815822 265/283 55-67 2.3/2.0 3.00 Forged
3835236 283 57-65 2.3/2.0 3.00 Forged
3836266 265/283 56-63 2.3/2.0 3.00 Forged
3849847 283 57-67 2.3/2.0 3.00 Forged
3876764 283 64-67 2.3/2.0 3.00 Nodular Iron
3876768 283 64-67 2.3/2.0 3.00 Nodular Iron
3884577 327 2.30/2.00 3.25 Forged
3892690 350 68-85 2.45/2.10 3.48 Forged
3911001 307/327 68-73 2.45/2.10 3.25 Nodular Iron
3911011 307/327 68-73 2.45/2.10 3.25 Nodular Iron
3914672 327 2.45/2.10 3.25 Forged
3923279 302 2.45/2.10 3.00 Forged
3932442 305/350 69-85 2.45/2.10 3.48 Nodular Iron
3941174 307/327 68-73 2.45/2.10 3.25 Nodular Iron
3941178 302 68-69 2.45/2.10 3.00 Forged
3941182 350 68-76 2.45/2.10 3.48 Forged
3941188 350 2.45/2.10 3.48 Forged
3949847 283 64-67 2.3/2.0 3.00 Nodular Iron
3951130 327 2.45/2.10 3.25 Forged
3951529 400 70-80 2.65/2.10 3.75 Nodular Iron
10106122 350 90-95 2.76/2.10 3.66 Forged LT-5 ZR-1
10168568 265 2.45/2.10 3.00 Cast One Piece Seal
12552216 346 2.558/2.10 3.62 Cast LS-1 One Piece Seal
14088526 305 1986 2.45/2.10 3.48 Nodular Iron One piece seal
14088532 350 86-88 2.45/2.10 3.48 Forged One piece seal
14088535 305/350 86 & UP 2.45/2.10 3.48 Nodular Iron One piece seal
14088552 350 86 & UP 2.45/2.10 3.48 Forged One piece seal


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That's just too hard to read. I think this looks better ! :cool:

Do you type these numbers in or do you copy and paste ???
A few easy changes on your side would make it a lot easier for me.

Download a PDF version here:


Chevy V8 bore & stroke chart


262 = 3.671" x 3.10" (Gen. I, 5.7" rod)
265 = 3.750" x 3.00" ('55-'57 Gen.I, 5.7" rod)
265 = 3.750" x 3.00" ('94-'96 Gen.II, 4.3 liter V-8 "L99", 5.94" rod)
267 = 3.500" x 3.48" (Gen.I, 5.7" rod)
283 = 3.875" x 3.00" (Gen.I, 5.7" rod)
293 = 3.779" x 3.27" ('99-later, Gen.III, "LR4" 4.8 Liter Vortec, 6.278" rod)
302 = 4.000" x 3.00" (Gen.I, 5.7" rod)
305 = 3.736" x 3.48" (Gen.I, 5.7" rod)
307 = 3.875" x 3.25" (Gen.I, 5.7" rod)
325 = 3.779" x 3.622" ('99-later, Gen.III, "LM7", "LS4 front wheel drive V-8" 5.3 Liter Vortec, 6.098" rod)
327 = 4.000" x 3.25" (Gen.I, 5.7" rod)
345 = 3.893" x 3.622" ('97-later, Gen.III, "LS1", 6.098" rod)
350 = 4.000" x 3.48" (Gen.I, 5.7" rod)
350 = 4.000" x 3.48" ('96-'01, Gen. I, Vortec, 5.7" rod)
350 = 3.900" x 3.66" ('89-'95, "LT5", in "ZR1" Corvette 32-valve DOHC, 5.74" rod)
364 = 4.000" x 3.622" ('99-later, Gen.III, "LS2", "LQ4" 6.0 Liter Vortec, 6.098" rod)
376 = 4.065" x 3.622" (2007-later, Gen. IV, "L92", Cadillac Escalade, GMC Yukon)
383 = 4.000" x 3.80" ('00, "HT 383", Gen.I truck crate motor, 5.7" rod)
400 = 4.125" x 3.75" (Gen.I, 5.565" rod)
427 = 4.125" x 4.00" (2006 Gen.IV, LS7 SBC, titanium rods)

Two common, non-factory smallblock combinations:

377 = 4.155" x 3.48" (5.7" or 6.00" rod)
400 block and a 350 crank with "spacer" main bearings
383 = 4.030" x 3.75" (5.565" or 5.7" or 6.0" rod)
350 block and a 400 crank, main bearing crank journals
cut to 350 size


366T = 3.935" x 3.76"
396 = 4.096" x 3.76"
402 = 4.125" x 3.76"
427 = 4.250" x 3.76"
427T = 4.250" x 3.76"
454 = 4.250" x 4.00"
496 = 4.250" x 4.37" (2001 Vortec 8100, 8.1 liter)
502 = 4.466" x 4.00"
572T = 4.560" x 4.375" (2003 "ZZ572" crate motors)

T = Tall Deck

ALL production big blocks used a 6.135" length rod.


348 = 4.125" x 3.25" (6.125" rod)
409 = 4.312" x 3.50" (6.010" rod)
427 = 4.312" x 3.65" (6.135" rod) 1963 "Z11" SHP drag race


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Written by David Reher

Once upon a time, a 454-cubic-inch engine was considered a big motor, and anything over 500 inches was referred to in awe as a “Mountain Motor”. But like Big Gulps and the budget deficit, everything is bigger in the 21st century – especially drag racing engines. While we’ve run 500-cubic-inch engines in Pro Stock since 1982, the rest of the drag racing world has adopted 600ci, 700ci, and even 800ci motors.

The one essential ingredient for a big-inch engine is a long-stroke crankshaft. The availability of reasonably priced aftermarket cranks has fueled the displacement inflation. When the only alternatives were factory forgings and high-dollar billets, racers had few choices. It’s a different world now with high quality crankshafts available with strokes that range from 4.250 inches up to 5.750 inches. And with the growing popularity of Top Sportsman and Pro Mod classes, the trend toward bigger and bigger engines is gaining momentum.

A long-stroke crankshaft is a highly specialized component, and not all cranks are created equal. When racers pulled crankshafts out of junkyards or bought over-the-counter factory forgings, they took what they could get. Now with the advent of affordable aftermarket cranks, racers face a bewildering assortment of materials, counterweight styles, oiling systems, and options. These choices have serious consequences when a 75-pound chunk of machined steel is spinning in the heart of an engine.

Balancing is a serious issue with long-stroke crankshafts. As the stroke increases, it takes larger and heavier counterweights to offset the weight of the rotating and reciprocating assemblies. I’m not an advocate of external balancing, which puts a portion of the required counterweight on the flywheel and balancer. I’m also not a fan of counterweighted flywheel flanges on crankshafts. While external weights do balance the crankshaft assembly overall, they also introduce torsional forces into the crankshaft by positioning some of the weight at the extreme ends of the crankshaft. Although a steel crankshaft seems quite rigid, in fact it twists and bends in response to power pulses and torsional forces. A crankshaft doesn’t have to fail to make the effects of this stress apparent: Worn bearings and cap walk (fretting of the main caps against the block) are signs of torsional bending.

A production V-8 crankshaft typically has six counterweights positioned at the front and rear of the crank. Many aftermarket crankshaft manufacturers offer “eight weight” designs with two additional counterweights adjacent to the middle main bearing journal. These center counterweights simplify balancing and significantly reduce the torsional loads on the crank.

While external balancing is less expensive than internal balancing, I believe it’s better to balance the crankshaft internally even if it’s necessary to install heavy metal in the counterweights. These heavy metal plugs must be installed parallel to the crankshaft axis by drilling holes through the counterweights and pressing the plugs in place. Plugs installed in the counterweights perpendicular to the crank axis can be dislodged by centrifugal force, turning them into heavy metal projectiles.

When we install heavy metal in a crank at Reher-Morrison Racing Engines, we don’t put all of it in the end counterweights. We drill through the first counterweight and into the second counterweight; in some instances, it’s necessary to drill through to the third counterweight as well. We then repeat this procedure on the other end of the crank. Each hole is progressively smaller, and the corresponding plugs of heavy metal are turned on a lathe to produce the correct interference fit. Distributing the weight throughout the crank in this manner also reduces the torsional loads on the crankshaft.

Hollow rod journals are a real asset for a long-stroke crankshaft. Drilling the crank pins to lighten the throws has the same effect on balancing as adding mass to the counterweights, but it produces a lighter overall rotating assembly. The longer the stroke, the more important it is to drill the crank pins. Most manufacturers offer drilled crank pins as an option, and it’s money well spent. Don’t be tempted to buy an “economy” crank when building a big motor; the cost of balancing with heavy metal can more than offset the low initial cost of an undrilled crank.

The position of the counterweights is also important to proper balancing. Unfortunately it’s difficult to determine whether the counterweights are in the right positions unless the crank is mounted on a balancing machine. If a crank needs a lot of material to be removed from one side of a counterweight and then a plug of heavy metal inserted at the opposite end, it’s likely that the entire counterweight is in the wrong place. It’s possible to balance a crank with this problem, but the fact that the counterweights aren’t indexed properly means that more weight is required to balance it than if the counterweights were in the correct positions.

A crude example of this is an out-of-balance tire. If a tire is mounted on a wheel and it’s way out of balance, often the easiest solution is to rotate the tire to a different place on the rim. Perhaps the wheel and tire are both heavy in one place; if both heavy sides happen to be together, it takes a lot of lead to balance them. But if the heavy sides of the wheel and rim are opposite each other, the overall balance is better and less lead is required. Applying this principle to crankshafts, if the counterweights aren’t in the right place, the balancing job is much more difficult and ultimately requires more weight to achieve a balanced state. An engineer could analyze the moments and angles of force that are involved, but I just know what I see on the crankshaft balancer.

Crankshafts are a complex subject, and I’ve already filled the available space for this column. Next month I’ll get into knife-edged counterweights and why you should never use a cross-drilled crankshaft.
Written by David Reher

There’s big money in sequels. Just ask George Lucas; he’s managed to extend the Star Wars series to nine movies. Unfortunately I don’t think this second installment of my two-part column on crankshafts is going to challenge Revenge of the Sith at the box office. After all, a crankshaft is just not as exciting as a light saber.

If you saved your May 27, 2005 edition of National DRAGSTER, now is the time to retrieve it from your workbench, nightstand, or race car. For those who have somehow have misplaced this issue, I’ll briefly review Part I.

It’s my opinion that the availability of affordable aftermarket crankshafts has fueled the move toward big-inch drag racing engines. We’ve seen a rapid escalation in engine displacement in sportsman competition, spurred by the growing popularity of Top Sportsman, Quick 32, fast bracket racing, and similar eliminators that put a premium on horsepower and top speed.

There are some significant differences among crankshafts, however. Last month I pointed out the importance of proper internal balancing and counterweight positioning in a long-stroke crank. This time my topic is oiling.

I’ll begin with a rather bold statement: Don’t use a cross-drilled crankshaft. There are a few exceptions to this rule, but under most circumstances, a cross-drilled crank is going to cause big problems.

Unfortunately cross-drilling is one of those terms that’s become part of the jargon of hot rodding. People who know very little about racing engines have heard of a “cross-drilled crank,” and mistakenly believe they’ve got to have one. In fact, cross-drilling simply refers to the position and routing of the holes that carry pressurized oil from the main bearing journals to the connecting rod bearings.

In a cross-drilled crankshaft, oil feed holes are drilled completely through the main journals so the passages are open on both ends. Holes from the rod journals are then drilled at an angle to intersect the holes in the main jouranls at the centerline of the crank. This system was thought to ensure a continuous supply of oil to the rod bearings because one end of the passage drilled through the main bearing is always exposed to the pressurized oil in the upper main bearing insert.

So what’s wrong with this picture? The pressurized oil that enters the feed hole through the main bearing journal must overcome the centrifugal force created by the rapidly spinning crankshaft before it can reach the passage to the rod journal. If the pressure created by the oil pump is not strong enough to counteract the centrifugal force that is pulling the oil away from the rod journal feed hole, then the rod bearing is starved for lubrication. Since the pinwheel effect of the centrifugal force increases with rpm, when the rod bearing does run dry and seize, the resulting carnage is usually catastrophic.

I learned my lesson about cross-drilled crankshafts the hard way. Back in the early ’80s we started to turn our engines faster. We’d been running stock Chevy cranks in our 287-cubic-inch small-blocks and B/ED motors without any problems. Eventually the supply of usable cranks became exhausted, so we ordered aftermarket cranks – “California cranks” as my Texan friends called them. These cranks were much prettier than the factory forgings, and they all had trick cross-drilled main bearings. It didn’t take long for those cranks to turn blue when the rod bearings burned, sometimes on the first or second dyno pull. Then we’d bolt in an old 283 crank and the engine would live forever. So what was the difference? The difference was the cross-drilling.

Today most racing crankshafts have a “high-speed” oiling system, which is essentially just how Chevy drilled those stock cranks. The oil feed holes for the rod bearings intersect the main journals at or near the surface of the journals. The pressurized oil does not have to overcome centrifugal force to reach the oil feed holes for the rod bearings, so the supply of lubrication is constant even at high rpm. There have been some refinements made to the angles and positions of the oiling holes to “time” the oil supply, but the basic design hasn’t changed significantly.

It’s easy to spot a cross-drilled crankshaft. Insert a piece of welding rod or coat hanger wire into the oil hole drilled in the main bearing. If the wire comes out the other side, the crank is cross-drilled. My advice is not to use it.

It is possible to crank up the oil pressure high enough to overcome the negative effects of cross-drilling. However, excessive oil pressure creates its own set of problems, increasing parasitic losses due to windage, excessive oil on the cylinder walls, and the power that’s consumed by turning a high-pressure oil pump.

It’s possible to manufacture a 5-inch stroke big-block crankshaft without cross-drilling the main journals. However, as the stroke becomes longer than 5 inches, the overlap between the main journals and the rod journals is reduced to the point that there is insufficient material for the oil feed holes. The crank manufacturer must then change the angle of the holes and drill them to intersect a cross-drilled passage in the main journal. When using this type of long-stroke cross-drilled crankshaft, it’s absolutely essential to increase the oil pressure and install a big dry-sump tank, because this engine is going to circulate a lot of oil.

It’s critical for anyone assembling an engine to inspect the crankshaft carefully. The first thing we do with every crank that comes into our shop is get out a pen light and a welding rod and check the oil holes. It’s not uncommon to find an oil feed hole that’s blocked or not drilled quite far enough. When assembling an engine, make sure that every oil passage is open and drilled where it is supposed to be.
Chevy Crankshaft Journal Sizes
Chevy V-8 Crankshaft Journal Sizes

There is a lot of misinformation on the internet about these numbers. We have taken the time to verify the data as much as possible. There still may be errors. Please lets us know if you find one.

Journal sizes are factory standard sizes. Your crankshaft journals may have been previously cut down by a machine shop. Make sure the crank you have is matched to your block. Blocks were made with specific journal sizes. Putting a small or medium journal, small-block crank into a medium or large journal, small-block block requires crank bearing spacers or special thick, aftermarket bearings
Chevy Small Block Journal Sizes
Gen. I, Small Journal
C.I.D. Main Rod
265 2.30 2.00
283 2.30 2.00
302 2.30 2.00
327 2.30 2.00
Gen. I, Medium Journal (Includes Vortec 305,350 to 1998.)
C.I.D. Main Rod
262 2.45 2.10
267 2.45 2.10
302 2.45 2.10
305 2.45 2.10
307 2.45 2.10
327 2.45 2.10
350 2.45 2.10
Gen. I, Large Journal
C.I.D. Main Rod
400 2.65 2.10
383, Gen. I, Non-Factory

Gen. I, 400 Crank in a Gen. I, 350 Block. Crank mains cut down.
C.I.D. Main Rod
383 2.45 2.10
377, Gen. I, Non-Factory

Gen. I, 350 Crank in a Gen. I, 400 Block. Spacer or Thick mains bearings.
C.I.D. Main Rod
377 2.10
Gen. II, Medium Journal

Includes: L99 265, LT1 350, LT4 350
C.I.D. Main Rod
265 2.45 2.10
305 2.45 2.10
350 2.45 2.10
302, Gen. II, Non-Factory

Gen. II, 265 L99 Crank in a Gen. II, 350 Block.
C.I.D. Main Rod
302 2.45 2.10
Gen. III

Includes: 1979-05 LS1 Corvette, Firebird, Camaro.
C.I.D. Main Rod
345 2.558 2.10
Corvette ZR1, LT5, DOHC.

Gen. II, 265 L99 Crank in a Gen. II, 350 Block.
C.I.D. Main Rod
350 2.76 2.10
Chevy Big Block Journal Sizes

T = Tall Deck
C.I.D. Main Rod
366T,396,402,427,427T,454,502 2.7488-2.7495 2.20
Chevy 348-409 W Journal Sizes
C.I.D. Main Rod
348,409,427 Z11 2.50 2.20

a few related and useful threads,













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sammy said:
GRUMPY, I HAVE AN OLDER 350 I want to, stroke to 383 and I have access to a SCAT 9000 cast steel crank , can I use my current connecting rods with new pistons?

Obviously I have no idea if the cranks balanced for 5.7 or 6" rods,or if its internally or externally balanced,or what pistons youll select ,nor the heads or cam, or a dozen other factors,Id suggest you have the block cleaned and inspected carefully and bored and honed if required,
scat usually does a good job of carefully checking crank dimensions but its your job to check clearances , anytime you build an engine its the builders responsibility to verify clearances, and youll almost always find a rotating assembly needs to be balanced, obviously the crank manufacturer can,t dictate what rods, pistons,piston pins, rings, damper or flywheel are used so the crank counter weights won,t be perfectly balanced
if you don,t think selecting high quality components and correctly assembling them is important, heres a visual reminder of the results of component failure under high stress.

READ THESE LINKS, as they contain a great deal of related info


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sammy said:
My new crank mic'd out less than .001 on the low side from standard on every journal.

I dropped it off today with the rest of the rotating assembly pieces for balancing. Money I won't regret spending..

Also picked up my new reworked Vortec heads, too. Screw in studs added, along with machined down valve guides and new seals, springs, chromemoly valve spring retainers, machined keepers, etc.

Looks like your on the right track to building a nice street engine!
Grumpy what is the typical HP & Torque limits of a Big Block Chevy Factory Forged Crank in good useable condition ?
That 427 Talk Deck Engine I have.

How can production Pontiac V8 cranks made of Nodular iron take 800 HP Like the 455 Crank ?
The Larger main journals a factor ?

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87vette81big said:
Grumpy what is the typical HP & Torque limits of a Big Block Chevy Factory Forged Crank in good useable condition ?
That 427 Talk Deck Engine I have.
I really don,t know how Id set the practical limitations. on a chevy forged crank because they were made from both 5140 and 4340 steel and stress is cumulative,so the age and mileage has an effect as does the care taken in clearancing and balancing the assembly. Ive used several stock, but reworked forged 427 and 454 cranks to build engines that produced well in excess of 600 hp and a couple 700hp engines so I have no doubt they are a strong crank.

How can production Pontiac V8 cranks made of Nodular iron take 800 HP Like the 455 Crank ?
The Larger main journals a factor ?

even a chevy cast steel crank can take a great deal of abuse for awhile as the harmonics are better absorbed in cast steel than forged (FOR A WHILE) but remember stress is cumulative, if I was building a serious engine and putting a good deal of cash into it ID vastly prefer it had a 4340 steel crank with forged rods having the better grade 7/16" ARP rod bolts.
almost all the "CRANK FAILURES" Ive looked at over the years were in fact NOT REALLY at the CORE ,CRANK FAILURES, but the result of other factors like rod bolts failures, GUYS not balancing the rotating assembly,guys not using a quality harmonic balancer, guys not clearancing the bearings correctly , valve train stability failures, main cap bolt stretching, failure to provide constant pressurized oil flow etc.
ITS HARDLY FAIR to consider a busted crank the cause of your problems if you have issues like this in the valve train











I am familiar with all bottom end race spec assembly parts Grumpy.
That new Hellcat Challanger engine is built real tough.
I read the specs.

It looks like only a Pontiac V8 has the Strongest Crankshaft Stock to compete against.
Reason why Mickey Thompson chose Pontiac in 1958-59.
BUT NEED $4-5 K.

A few guys have built 7-second 455 Engines using stock Poncho 455 Crabkshafts.
Never broke them.

GM Guys going to take a beating on Street & Dragstrips soon Grumpy.
Hellcat will Dominate All.
yes I agree being broke all the time SUCKS BIG TIME!
and having a bunch of projects you would love to dive into with full effort only to be held back by the need to pay mandatory bills rather than spend cash on optional discretionary parts and machine work, on a hobby is just what needs to be done unfortunately, frustrating but its obviously whats required.
and BTW the tall deck block you have may not be in high demand but I think thats mostly because the average guy building a BBC has no concept of the potential benefits the taller deck height and use of longer rods,can potentially provide.

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grumpyvette said:
yes I agree being broke all the time SUCKS BIG TIME!
and having a bunch of projects you would love to dive into with full effort only to be held back by the need to pay mandatory bills rather than spend cash on optional discretionary parts and machine work, on a hobby is just what needs to be done unfortunately, frustrating but its obviously whats required
Yes Grumpy.
The Only other way is to collect lightly used Racing parts for a Big Block Chevy.
They don't show up on fleabay hardly at all.
Other Race sights they do. Still need $$.

Have to raise my Boys & take care of the wife 1st.

I can't even compete with my late friends 410sbc.
He never imagined 707 HP be available in a new Domestic car.

Boosted requires custom dished pistons of some sort.
Very thick Crown & Low than normal Top ring placement to withstand extreme boost pressures & Heat generated .

See what happens in next year.
Right now I can only pull it off with Pintuac 389-455 engines I have put away.
allen said:
Grumpy, I want to build a kick ass 496 BBC for street & strip use that will stand up to frequent street driving, I realize mileage will probably suck, because I have a 4l80E transmission and 4.11:1 rear gears and 28" tall tires ,but my main concern is the choice between selecting a cast steel crank and a forged version, and internal vs external balance.

the first question Id ask is what type of car or truck its to be installed in,and its weight,and if you need to pass emission testing and how much of the actual work will you be doing vs paying for others to do?
next what heads and intake will you be using?, what compression ratio? what stall speed on the converter?
and what type of cam? theres a great deal of missing info, but in general if you build a 496 BBC the cast or nodular iron cranks can usually handle about 650 hp and 6000rpm peak stress levels,occasionally, without problems ,above that Id suggest going for all forged components , and keep in mind on a 496 with its 4.25" stroke its the connecting rods and pistons and valve train that are more common failure points than the crank material and the longer 6.385" rods with 7/16" bolts are preferable.
THE Scat 9000 ,cast steel crank Scat I beam rods with 7/16" rod bolts and forged pistons is all you need on a hot performance engine 496 BBC street car. As far as internal or external balance. you can Go with whatever is cost effective with what parts you have, but ID sure select 6.385" length connecting rods Either ,internal or external balancing will work with a street car, but internally balance in theory has an edge with less internal vibration.


you might also want to add up all the parts, gaskets and machine work costs, and compare the total to a crate engine with a warranty

http://www.vortecproperformance.com/eng ... tions.html

http://www.tristarengines.com/catalog/h ... heads.html

http://www.newgmengines.com/shop/gm-goo ... -engines/8
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