do you match the cam to the engine or build the engine to match the cam specs?

Grumpy · Oct 28, 2015

"do you match the cam to the engine or build the engine to match the cam specs?"
I got asked that question a few days ago, frankly I have never ever considered doing it either way
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
http://garage.grumpysperformance.com/index.php?threads/semi-fool-proof-cam-sellection.82/

http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

http://garage.grumpysperformance.com/index.php?threads/dynamic-vs-static-compression.727/

IT helps to know exactly what year and casting number your engine block is as early production big block engines used a different rear cam bearing and cam, a potential rear cam bearing oil flow issue is found on the 1965- too a few very early 1967 engines ,if you install the older design BBC cam with a grooved rear main in EITHER config with EITHER rear bearing your covered, and since thats just not expensive and any decent machine shop can modify any cam like that cheaply is the smart route to take if your in doubt. obviously having the machine
shop groove the rear cam journal under the cam bearing in the block like the later BBC engines would be ideal.
Btw heres a tip learned through experience , 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.
https://www.holley.com/products/intakes/single_plane_manifolds/parts/7620

http://www.engineersedge.com/lubrication/molybdenum_disulfide_characteristics.htm
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

first CHEVK CLEARANCES AND GEOMETRY

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.

when assembling any engines valve train component parts and bearing surfaces,should be carefully cleaned and soaked with moly spray and then coated with moly assembly lube prior to assembly, Moly exists as microscopic hexagonal crystal platelets Several molecules make up one of these platelets. A single molecule of Moly contains two sulfur atoms and one molybdenum atom. Moly platelets are attracted to metal surfaces. This attraction and the force of moving engine parts rubbing across one another provide the necessary thermochemical reaction necessary for Moly to form an overlapping protective coating like armor on all of your engine parts. This protective armor coating has a number of properties that are very beneficial for your engine.

The Moly platelets that make up the protective layers on your engine surfaces slide across one another very easily. Instead of metal rubbing against metal, you have Moly platelets moving across one another protecting and lubricating the metal engine parts.

This coating effectively fills in the microscopic pores that cover the surface of all engine parts, making them smoother. This feature is important in providing an effective seal on the combustion chamber. By filling in the craters and pores Moly improves this seal allowing for more efficient combustion and engine performance.

This overlapping coating of Moly also gives protection against loading (perpendicular) forces. These forces occur on the bearings, and lifters. The high pressures that occur between these moving parts tend to squeeze normal lubricants out.

http://garage.grumpysperformance.com/index.php?threads/cam-bearing-install-tools-install-info.1479/

Chevy V8 bore & stroke chart

CID BORE STROKE
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

ALL production big blocks used a 6.135" length rod.
CHEVY BIG BLOCK V-8 BORE AND STROKE

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"
477= 4.5" bore x 3.76" stroke
496 = 4.250" x 4.37" (2001 Vortec 8100, 8.1 liter)
502 = 4.466" x 4.00"
557T= 4.5 bore 4.375" stroke
572T = 4.560" x 4.375" (2003 "ZZ572" crate motors)

T = Tall Deck

ALL production big blocks used a 6.135" length rod.

http://garage.grumpysperformance.co...k-after-a-cam-lobe-rod-or-bearings-fail.2919/

http://garage.grumpysperformance.com/index.php?threads/cam-wear-articles-you-need-to-read.282/

http://www.compcams.com/Pages/413/cam-timing-lobe-separation-angle.aspx
with an engineering back ground Id grab a long legal pad of lined paper and a decent ball point pen, and pocket calculator,

and list the intended power (IE torque & ,rpm required & limitations) the cars weight drive train or modifications to that drive train, the realistic financial budget and time frame, available resources I have to work with, personnel assets, tools available.
Id realize that the less time wasted in return wasted trips to the local machine shop or reordering parts I forgot to order like bearings fasteners or sealants, gaskets or lubricants, were all going to slow up the process of completing the engine assembly, and that some times just not checking a clearance can cost you several days time so its well worth the cost to buy your own precision measuring tools, its also not mandatory to buy the very best and most accurate and expensive tools available and you can do a remarkably good job with a decent dial caliper and plasti-gauge, if thats all you have available
http://garage.grumpysperformance.com/index.php?threads/bare-minimum-tools.11026/#post-48766

PAINTING THE non-machined surfaces and coating the machined surfaces with a good anti-rust coating like wd40 specialist helps

http://garage.grumpysperformance.com/index.php?threads/storing-an-engine-block.12262/#post-60147

KEEP IN MIND THERES SEVERAL VERSIONS OF WD40 SPECIALIST
YOU WANT THE LONG TERM CORROSION INHIBITOR

Building an engine around a cam is going to be, a very limited concept,simply, because the idea assumes that a set lift and duration and LCA is maxed out with a perfectly matched set of components, and frankly the math to prove that would be mind bending-ly complex in that a single factor like the temperature of the exhaust gases exiting the exhaust port could change the results, deciding on all the components that will be used on an engine build, by looking at the cam lobe design alone, would be a bit like deciding on the correct gal too marry, based, solely on , looking over her hand selected luggage and her hand selected negligee color alone.
A camshaft is a mechanical device, used to control valve speed acceleration, lift rates for that duration and that in theory controls air flow rates through the cylinders at various rpm rates, It's the cam lobe lift and duration rates matched to the port volume and cylinder displacement, piston size and engines stroke and rod length that determine the way air enters and exits the cylinder, that is designed to optimize that airflow in and out of the cylinder, for a specific application, but the cylinder head design, intake design,exhaust header and several other factors like displacement, compression, fuel/air ratio, ignition advance curve,ignition voltage,combustion chamber shape, exhaust collector design,fuel and its octane and engine rpm all can and will change and effect the results your engine will produce.
frankly I think the logical approach is to ask what the engines to be used for, what the customer currently has to work with, or wants to work with, and what his budget limitations and time frame are.
a properly selected cam will tend to help you compensate for areas where you could not get the best possible flow rates, or to increase or decrease cylinder fill rates over a certain rpm range.
example heres what a change in cam LCA does

in mind valve lift and port flow limitations[/color]
http://www.wallaceracing.com/runnertorquecalc.php
http://www.wallaceracing.com/ca-calc.php
http://www.wallaceracing.com/area-under-curve.php
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
http://www.circletrack.com/enginetech/1 ... ch_engine/
USE THE CALCULATORS to match port size to intended rpm levels... but keep in mind valve lift and port flow limitations[/color]

http://www.wallaceracing.com/runnertorquecalc.php
http://www.wallaceracing.com/ca-calc.php
http://www.wallaceracing.com/area-under-curve.php
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
as a general rule you'll find single plane intakes on a SBC generally work best on engine combos with at least a 245 duration cam at .050 lift and with 10.7:1 or higher compression and solid lifter cams that can operate efficiently in the 5500rpm-7000rpm PLUS power band and geared to operate in that same 5500rpm-7000rpm PLUS power band most of the time.
this also requires a short block assembly designed to operate in that upper rpm band, now as the engine displacement is increased, like in the larger displacement BBC engines port and runner air flow speeds will also increase so the effect is that a larger BBC engine can use more, or longer cam duration at a given rpm band, due to its larger cylinder volume to valve curtain area requiring more time, for effective cylinder fill and scavenging .

thus a 2.02 valve sbc reaches max flow near .505 lift
thus a 2.19 valve BBC reaches max flow near .5475 lift

Calculating the valve curtain area
The following equation mathematically defines the available flow area for any given valve diameter and lift value:
Area = valve diameter x 0.98 x 3.14 x valve lift
Where 3.14 = pi (π)
For a typical 2.02-inch intake valve at .500-inch lift, it calculates as follows:
Area = 2.02 x 0.98 x 3.14 x 0.500 = 3.107 square inches

For a typical 2.19-inch intake valve at .550-inch lift, it calculates as follows:
Area = 2.19 x 0.98 x 3.14 x 0.550 = 3.714 square inches

a typical 383 sbc with that .500 lift cam, has 47.875 cubic inches of volume in a single cylinder, divide that by the curtain area of 3.107 and you get 15 cubic inches of cylinder volume for each square inch of valve curtain

a typical 496 BBC with that .550 lift cam, has 62 cubic inches of volume in a single cylinder, divide that by the curtain area of 3.714 and you get 16.69 cubic inches of cylinder volume for each square inch of valve curtain, or about 11% less available air flow even with the larger valve and higher lift cam, to compensate use of a tighter LCA is frequently used to allow a longer, and more effective cylinder scavenging time frame in the big block combo

If your designing a performance engine application, you obviously would match the most effective cylinder head port cross sectional area, valve curtain area, valve lift,header design, engine displacement and rpm power band to the cams intended RPM range, engines power band, and GEAR, the cars drive train, so it stays in that operational rpm band the vast majority of its time, while keeping the engine just under the engines critical upper rpm red-line limitations , so its durability is never stressed to the point its life spans compromised, when pushed hard to shift to maximize power.
you would then look at what was available within the budget and logically select the most efficient and cost effective combination of components you could assemble.
you would obviously want to know the car owners experience, what his skill level was, what work he was willing and comfortable doing, and if he had the tools and or a machine shop access locally .
and with experience you learn to avoid chronic weak points in the factory engine design, if the factory connecting rods have an annoying habit of snapping at 6000rpm after a few months youll gain that knowledge through experience , and have long ago swapped to stronger rods, if the factory oil system required a known modification youll have known how to do it .
Keep in mind most guys don,t get past the "lets slap a cam, intake carb, and headers on this car and go racing stage"
I'd bet less than 10% of the guys that claim to be into hot rodding have ever custom built parts like oil pans, or installed a different ring & pinion gear ratio

related links
I'M SIMPLY GIVING YOU INFO SHOULD THE NEED ARISE
YES ITS WORTH READING THROUGH AS EDUCATIONAL INFO
http://garage.grumpysperformance.com/index.php?threads/bits-of-383-info.38/

http://garage.grumpysperformance.com/index.php?threads/tips-on-building-a-383-sbc-stroker.428/

http://garage.grumpysperformance.com/index.php?threads/stroker-tips-by-len-emanuelson.1249/

http://garage.grumpysperformance.com/index.php?threads/more-port-flow-related-info.322/

http://garage.grumpysperformance.com/index.php?threads/block-prep.125/

http://garage.grumpysperformance.com/index.php?threads/engine-block-cylinder-wall-thickness.976/

http://garage.grumpysperformance.co...ty-thats-key-in-building-a-good-engine.11682/

http://garage.grumpysperformance.com/index.php?threads/checking-piston-to-valve-clearances.399/

http://garage.grumpysperformance.co...lding-a-350-or-upgrading-too-a-383-sbc.11408/

http://garage.grumpysperformance.co...g-and-installing-connecting-rods-pistons.247/

http://garage.grumpysperformance.com/index.php?threads/checking-piston-to-valve-clearances.399/

http://garage.grumpysperformance.co...tion-of-crank-durring-short-blk-assembly.852/

http://garage.grumpysperformance.co...ould-you-build-a-350-or-a-383-sbc-combo.8310/

http://garage.grumpysperformance.com/index.php?threads/rods-that-don-t-destroy-your-budget.10958/

http://garage.grumpysperformance.co...ectly-and-get-it-to-last-cam-install-info.90/

http://garage.grumpysperformance.com/index.php?threads/350-383-rebuild.11115/

http://garage.grumpysperformance.co...ing-parts-and-a-logical-plan.7722/#post-68651

http://garage.grumpysperformance.com/index.php?threads/upgrade-choices.11416/

http://garage.grumpysperformance.com/index.php?threads/finding-a-machine-shop.321/

http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/

http://garage.grumpysperformance.co...l-pumps-pressure-bye-pass-circuit-works.3536/

http://garage.grumpysperformance.com/index.php?threads/matching-parts-and-a-logical-plan.7722/

http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-52469

http://garage.grumpysperformance.com/index.php?threads/what-to-look-for-in-a-good-engine-combo.9930/

http://garage.grumpysperformance.com/index.php?threads/bits-of-383-info.38/

Grumpy · Nov 1, 2015

stepping back and thinking through the basics\ limitations and goals

THINK THROUGH YOUR OPTIONS AND THE COMPLETE COMBO,
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.
just for discussion sake here.....
lets discuss why you factor in piston speeds
Ill point out that the probable strength limitations,
in the 355 block and rotating assembly
(assuming good forged components and ARP main studs are used)
yes as pointed out earlier, both engines below would be pushing well past the limitations imposed by a STOCK, O.E.M. production block
but assuming that the O.E.M block will hold up at least for a hundred 1/4 mile passes,before it comes violently apart at peak rpm, that stress limitation,
will be imposed by both common valve spring limitations and piston speed on the rotating assembly and block,
on a 355 chevy with its 3.48" stroke , (assuming a 4200 fpm max reasonable piston speed)
has a peak rpm near 6700-7200 engine rpm, selecting a cam that peaks below about 6700 rpm-7000 rpm,)
leaves the potential advantage of that shorter stroke the 355 sbc on the table.
this is one reason that the 383 with its longer 3.75" stroke is currently the most popular combo with a 4.30 bore block.
if your going to build a 355, then you may as well take full advantage of the engines potential strong points.
a similar longer stroke 383 would be limited to about 6300 rpm-6700 rpm but the trade off is about 40 ft lbs more torque over most of the potential power band
the formula for hp is
torque x rpm/5252= hp
if both engines make about 1.2 hp per cubic inch
the 383 will peak about 400 rpm lower than the 355 if both are built to maximize the engines potential strong points
just for giggles and to point out
why you maximize a RACE ENGINE potential RPM LIMITS
lets assume the 355 power peak is at about 6800 rpm and,
the similar 383 would be peaking nearer 6400 rpm
if you have 1.2 x 355=426 ft lbs x 6800 rpm /5252=551 hp
if you have 1.2 x 383=460 ft lbs x 6400 rpm /5252=560 hp

I've noticed a wide spread almost universal tendency for many guys to want to jump into any project with both feet with a credit card in hand!
Id bet in the vast majority of cases a few days spent looking into correctly matching the flow capacity,intended rpm range,and strength
capability's of many of the components and doing some research into the intended stress and rpm levels and limitations would do wonders for the eventual outcome of the final combos being built, example piston speeds should rarely exceed 4200 feet per minute, hydraulic cams tend to work best at under 6300 rpm and with reasonable lift to duration acceleration rates, and a bit of research will show that some of the most radical versions push past the physical limits of a stable valve train by 6300-rpm.
as usual the higher the power to weight ratio the easier it will be to both accelerate, stop or turn a car.
I can,t do more than make a tiny chip in the amount of related threads but heres a few charts and links to give you some ideas.
you've got lots of options , if your building a big block Chevy engine, and the 454-496 (stroked 454 with a 4.25" crank) is very popular for a reason, it can produce exceptional power in the 2500-rpm-6500-rpm range generally used on a street/strip weekend toy for the money spent. one secret is DON,T OVER CAM the engine on a street driven car, and that will generally mean youll want a cam in the 230-245 duration @ .050 lift range, a 9.5-10.5:1 compression and oval port heads, a manual transmission or automatic with a 2800-rpm-3100-rpm stall converter and a 3.36:1-3.73:1 rear gear ratio
but Id make a couple suggestions based on past experience.
both the 502 and 454 have 4" stroke cranks, the difference in displacement is the result of piston and bore diameter being larger in the 502, selecting a cam with a much tighter LSA in the 106-108 range tends to produce more power in my experience
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.
Chevy V8 bore & stroke chart
I saw this online and figured I would post it..I am going to add the popular lsx strokers soon
CID BORE STROKE
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

--------------------------------------------------------------------------------

CHEVY BIG BLOCK V-8 BORE AND STROKE

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.

http://www.race-cars.net/calculators/compression_calculator.html

http://garage.grumpysperformance.com/index.php?threads/a-few-calculator-links.7108/#post-27382

http://www.projectpontiac.com/ppsite15/compression-ratio-calculator

degree it in correctly and get it to last,cam install info,

most guys don,t build enough engines or change enough cams to see the trends and a great many engines are built where the owner uses the dot-to-dot install on the cams timing set. this is almost always the first major mistake made. read the linked threads and SUB LINKS...

garage.grumpysperformance.com

http://www.wallaceracing.com/dynamic-cr.php

http://www.rbracing-rsr.com/comprAdvHD.htm

http://performancetrends.com/Compression_Ratio_Calculator_V2.3.htm

http://www.wallaceracing.com/cr_test2.php

http://www.pcengines.com.au/calculators/Calculate dynamic Comp Ratio.htm

http://www.csgnetwork.com/compcalc.html

http://www.diamondracing.net/tools/

https://www.uempistons.com/index.php?main_page=calculators&type=comp

https://www.rbracing-rsr.com/compstaticcalc.html

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
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
Horsepower = (RPM x Torque) ÷ 5,252

Torque
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

read these links and the sub links

http://garage.grumpysperformance.com/index.php?threads/stroke-it-or-get-head.11960/#post-56981

http://garage.grumpysperformance.co...ting-big-block-chevy-454-cam-dyno-test.10181/

http://garage.grumpysperformance.co...y-in-building-a-good-engine.11682/#post-54682

http://www.brodix.com/heads/big-block-chevrolet-compatible-heads

http://www.trickflow.com/search/pro...al-280-cylinder-heads-for-big-block-chevrolet

http://www.airflowresearch.com/index.php?cPath=68

http://garage.grumpysperformance.co...ng-piston-pin-height-compression-height.5064/

a good oval port single plane intake even on the street can produce decent power if the correct gearing, and transmission combo is used to take advantage of the flow characteristics of the matched cam timing and head flow, exhaust scavenging of a properly matched header etc.
keep in mind a good street/strip combo must run on available pump octane fuel and durability and low maintenance costs are more important to most owners than a couple extra peak hp they can seldom access as most street tires will never keep up with the engine torque produced, and if your using the car for transportation it must be 100% dependable

you may find this info useful, on CRANK SHAFT STRENGTH
MATERIAL....................TENSILE STRENGTH.....PSI.
CAST
CAST IRON.....................APROX 75,000
NODULAR IRON................APROX 95,000
CAST STEEL...................APROX 105,000
FORGED
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
the problem is that unless you take the time to calculate out exactly what your doing and how you intend to reach your goal and which components you'll use to do it, your basically at best guessing.
lets look a a few factors.

RPMS/VS STRESS

this is a great example of why you must carefully inspect every part you use very carefully BEFORE USE!

yes everyone rightly expects, new out of the box components to be in pristine , and flawless condition, The fact is that a small but significant percentage of parts will be factory new BUT DEFECTIVE! or occasionally the new parts in the box, will not be the part ,that matches the part number...

garage.grumpysperformance.com

related info, that you might need
http://garage.grumpysperformance.co...heads-for-small-block-chevys.3293/#post-26213

http://garage.grumpysperformance.com/index.php?threads/what-are-these-heads.4702/#post-12742

http://garage.grumpysperformance.co...-by-step-guide-with-pictures.5378/#post-71848

http://garage.grumpysperformance.co...ther-efi-intake-manifold-info.431/#post-26322

http://garage.grumpysperformance.com/index.php?threads/porting-can-help.462/page-3#post-59145

http://garage.grumpysperformance.co...ads-tuned-intake-turbulence.12998/#post-67611

Volume (CCs) of Head Gasket
CCs of Head Gasket = Bore x Bore x 12.87 x Thickness of Head Gasket
COMMON SBC INTAKE PORTS
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
http://users.erols.com/srweiss/calccsa.htm

Your RPM computed from your Cross Sectional Area of 1.95
(the smaller AFR HEADS)
and Bore of 4.03 and Stroke of 3.75 is 5,569.12 .

Your RPM computed from your Cross Sectional Area of 2.05
(the Larger AFR HEADS)
and Bore of 4.03 and Stroke of 3.75 is 5,854.72 .
you,ll barely notice the about 300 rpm shift in the power band on the lower part of rpm range but appreciate it much more on the upper edge of that power curve

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
vortec......................1.66.............170
tfs195......................1.93.............195
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

USE THE CALCULATORS
http://www.rbracing-rsr.com/runnertorquecalc.html
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
http://www.superchevy.com/how-to/en...-0902-chevy-engine-port-variations-measuring/
http://www.hotrod.com/articles/choosing-the-right-camshaft/
http://garage.grumpysperformance.com/index.php?threads/bits-of-383-info.38/
BTW.IF YOUR BUILDING A SBC
http://brodix.com/heads-2/small-block-chevrolet-compatible-heads/ik-series
http://www.jegs.com/i/Brodix/158/1021001/10002/-1

brodix ph# 1-479-394-1075 (ALWAYS VERIFY PART NUMBERS SEVERAL,
TIMES FROM AT LEAST TWO SOURCES, BEFORE ORDERING PARTS)
the brodix rock stud girdle is part # BR-6435 and LIST price is about $230 you can get it for less if you shop carefully
BE AWARE that the I.K. 200 heads were shipped with BOTH 3/8" and 7/16" rocker studs ,
and the poly locks for the 7/16" rocker studs ONLY fit that rocker stud girdle
obviously you need to verify what your heads have before you order the matching rocker stud girdle

Grumpy · Feb 21, 2016

maybe its just the 40-50 years of experience of dealing with both the cars I work on and the people I,ve dealt with, but it helps , to be realistic about your goals, and resources.
when your planning an engine it generally helps a great deal to mentally step back and honestly ask yourself exactly what your intended use for that engine will be.
a performance engine built for a street/strip car, will by definition be very different than a engine built for a car thats primarily raced and probably taken to the track on a car trailer.
you'll also generally want to select durable components, in almost every case vs the newest ,supposedly trick parts available and let other people run the expense time and frustration involved in testing the newest cutting edge parts, because you'll generally want the engine to run with minimal maintenance issues, over a longer term use,and not spend every available spare minute swapping out or testing parts for the manufacturers at your expense, its better to deal in known and dependable components you can trust from reputable trusted manufacturers.
Yes that could mean you might be running at a slight power disadvantage, over the guys with unlimited bank balances, but over the long term youll tend to finish far more races with the cars drive train still fully functional and spend considerably less wasted money and time wasted. no one I know really wants to constantly tweak and adjust an engine to keep it running.
It helps of course to understand that your choices are ALL going to be compromises in some areas , your fuel source , and its octane limitations , technical limitations like power to weight ratios, compression, potential detonation issues, engine heat, issues, the drive train and gearing, the transmission your using among other, things, like your bank balance, your skill level, access to tools and a place to work, will obviously limit some choices.
when most of the newer younger guys I talk too start looking at an engine choice or the mods they want to do,
I,ve always been rather amazed that almost all of them, never even consider, that they don,t necessarily need too,
or logically may not even want too, use the cars current engine as a starting point.
Ive always been a firm believer that in most cases, if you use the car for transportation, you want to build a second engine, to play with,
, so you have the option to swap the original engine back into the car, should something go wrong, thus at least eventually over a long week end, maintaining the cars potential use as transportation.

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.

http://garage.grumpysperformance.com/index.php?threads/octane-boosters.613/#post-1379

http://garage.grumpysperformance.co...temps-detonation-resistance.12842/#post-66647

http://garage.grumpysperformance.co...octane-for-compression-ratio.2718/#post-35581

http://garage.grumpysperformance.com/index.php?threads/detonation-pre-ignition.208/#post-487

http://garage.grumpysperformance.com/index.php?threads/detonation-damage.2883/#post-31942

http://garage.grumpysperformance.com/index.php?threads/toluene-octane-calculator.11278/

http://www.race-cars.net/calculators/compression_calculator.html

http://garage.grumpysperformance.com/index.php?threads/a-few-calculator-links.7108/#post-27382

http://www.projectpontiac.com/ppsite15/compression-ratio-calculator

http://www.wallaceracing.com/dynamic-cr.php

http://www.rbracing-rsr.com/comprAdvHD.htm

http://performancetrends.com/Compression_Ratio_Calculator_V2.3.htm

http://www.wallaceracing.com/cr_test2.php

http://www.pcengines.com.au/calculators/Calculate dynamic Comp Ratio.htm

http://www.csgnetwork.com/compcalc.html

http://www.diamondracing.net/tools/

https://www.uempistons.com/index.php?main_page=calculators&type=comp

https://www.rbracing-rsr.com/compstaticcalc.html

Indycars · Feb 21, 2016

When I was into racing karts at the regional level (and local level) it was
always important to me to show up prepared to test and race.....not repair
and test then race at the race track. I was not the fastest but I could beat half
the field by completing the race. I would say that I completed 90% of races
without a failure.

In fact I won the last race of the season for the US region IV
championship against my number one competition from Ohio, I had a brake
rotor failure in practice. I had to borrow a chassis and install my engine to win
when he failed to complete the last of 3 heats in kart racing.

Sorry I could not predict a rotor failure....... don't have a Formula 1 budget. heheheh !!!

87vette81big · Feb 21, 2016

It was hard decision Grumpy.
C4 Corvette Vs. Hellcats.
70-1/2 T/A Race Gas 110 motor Octane Race Engine 455 .
Really it came down to Big Tube Header availability.
Big Tube 2.00 " Primary Tubes no problem Pontiac V8. I have them,
Don't cost 2,000 bucks or more either.

Yes I know what a Street engine is.
87-93 octane pee water gas burner.

Indycars · Feb 21, 2016

87vette81big said:
Yes I know what a Street engine is.
87-93 octane pee water gas burner.

Thanks for the complement!!!

87vette81big · Feb 21, 2016

Indycars said:
Thanks for the complement!!!

1500Lbs T-bucket of yours Rick.
A C4 is 3200 lbs no Driver.
My TA is 3250-3300 lbs.

Gearing and Hooking up is Key.
No matter Power to Weight Ratio.
Low gears help.
Street ability suffers.
You and me have an edge.
Your Ford 9inch & my Pontiac 9.3 rears you can change gears in 20 minutes .
Just need another 3rd member built ready to go.

Grumpy · Feb 19, 2018

Again, much appreciate the replies!

grumpyvette
Ha! You are one of the reasons I have yet to finalize cam selection. You've been so prolific in very kindly compiling and offering up so much cam related info over the years that, what I use to easily decide on, now has me double-thinking.

I'm always rather amazed at the number of people that don,t logically mentally step back and ask themselves, a couple simple question, especially if they are not personally familiar with the tech aspects of the subject at hand.
but , Id point out that if your wondering why some cams have a longer exhaust duration, the basic fact here is, that longer exhaust duration, in some cam designs is a design factor whose main purpose is to allow a slightly longer time frame for the cars with a restrictive stock exhaust port to have exhaust flowing that longer time frame is being designed in to the engine too allow a constrictive exhaust time to let the pressure bleed down.
an engine with a non-restricted exhaust (open properly tuned headers, or properly tuned headers feeding a very low restriction exhaust) (and yes the size and length can be both calculated and the restriction easily measured) has no need for a longer exhaust duration, as cylinder scavenging with a properly matched intake manifold, displacement port flow cam timing and compression can be properly matched and would function correctly with a cam timing on both the intake and exhaust matched to a certain rpm and power range.

I've written several related threads, with plenty of related and detailed sub-links
it could easily take a couple very well spent hours to read the links and sub-links but youll gain a good deal more insight into how an engine functions,
its all a learning process, you want too simply want to mentally take a step back, take a deep breath or two,
and start testing to find out whats working correctly,in your current combo,
whats not working up to your expectations,and if its not meeting your goals, logically calculate what should change,
and then calculate what can be adjusted or if necessary parts that can be logically replaced, and re-tested,
if that required too improve the performance.
don,t make the all too common mistake of thinking adding horsepower is the only route to improved performance.
suspension mods, better shocks, better brakes, a stiffer frame, larger diameter and wider tires, and drive train gearing and removing weight,
and correctly setting up the cars chassis to more effectively apply weight transfer ratios,
swapping to lower weight parts,or stronger , or more durable parts, use of stronger drive train components, better matched gear ratios, all help

well I'll assume you previously read the links on engine building,and quench, and you have at least tried to build a well balanced combo with reasonable quench,and tried to match the cam duration and lsa to the engines compression and intended power range, and you selected a fairly well matched cam timing and reasonable compression, but at this point in the tuning ,your still having indications your getting into detonation.
keep in mind that keeping reasonably consistent and as low as practicable , combustion chamber temps are a huge factor in avoiding detonation issues, having an auxiliary oil cooler and a trans fluid cooler with a powered fan, and the proper fuel/air ratio and ignition advance curve along with matching your cars engine dynamic compression ratio to the available fuel octane can go a long way toward avoiding detonation issu

http://garage.grumpysperformance.com/index.php?threads/semi-fool-proof-cam-sellection.82/

http://garage.grumpysperformance.co...mbers-or-a-good-street-combo-your-after.5078/

http://garage.grumpysperformance.co...plit-cam-and-cam-suggestion.12294/#post-61178

http://garage.grumpysperformance.co...ng-to-take-awhile-but-theres-good-tips.15295/

http://garage.grumpysperformance.com/index.php?threads/is-backpressure-hurting-your-combo.495/

http://garage.grumpysperformance.co...-the-extra-cost-vs-a-flat-tappet-design.3802/

http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/

http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

http://garage.grumpysperformance.co...-guys-that-just-slap-on-factory-headers.3155/

http://garage.grumpysperformance.co...ectly-and-get-it-to-last-cam-install-info.90/

http://garage.grumpysperformance.co...-guys-that-just-slap-on-factory-headers.3155/

http://garage.grumpysperformance.co...-the-charts-calculators-and-basic-math.10705/

http://garage.grumpysperformance.co...gine-to-match-the-cam-specs.11764/#post-55571

http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

http://garage.grumpysperformance.co...y-in-building-a-good-engine.11682/#post-54682

Grumpy · Feb 4, 2020

TIGHTER 104-110 LSA tend to increase scavenging efficincy but at the cost of less smooth idle

LSA lobe separation angle is locked into the cam when its ground and can not change, if its ground at 110,degrees or 114 degrees it will stay that figure
and
LCA lobe center angle, can be changed
if you advance the cam 4 degrees both the intake and exhaust lobe opening and closing points open and close 4 degrees earlier.
if you RETARD the cam 4 degrees both the intake and exhaust lobe opening and closing points open and close 4 degrees later.

AS your displacement per cylinder increases the effective valve size per cubic inch decreases so you need a slightly tighter LSA and these charts should help.

0607phr_11_z+camshaft_basics+lobe_centerline_angle_determination_chart.jpg

do you match the cam to the engine or build the engine to match the cam specs?

Grumpy

The Grumpy Grease Monkey mechanical engineer.

Grumpy

The Grumpy Grease Monkey mechanical engineer.

degree it in correctly and get it to last,cam install info,

this is a great example of why you must carefully inspect every part you use very carefully BEFORE USE!

Grumpy

The Grumpy Grease Monkey mechanical engineer.

Indycars

Administrator

87vette81big

Guest

Indycars

Administrator

87vette81big

Guest

Grumpy

The Grumpy Grease Monkey mechanical engineer.

Grumpy

The Grumpy Grease Monkey mechanical engineer.