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Head selection

eoseitz

Well-known member
Joined
Sep 22, 2009
Messages
154
Location
Marion, OH
Corvette
1974 Stingray L82
I've been posting a lot lately, but with the warm weather I've had a lot of time to work on the 74. I was wondering what some of you would suggest for a good head upgrade. My car has had the motor swapped out. It's a 76-77 LM1 out of a camaro. The specs are below:

Block39700102 bolt main
Crankshaftcast iron
Cylinder Head3338821.94/1.5" Valves, 75.47cc
Cam14060651
Intake14014440
RH Exhaust346248
LH Exhaust381863could be 361863


The previous owner installed an Edelbrock performer intake, performer 650 carb and possibly a mild cam. I'm not sure of the cam size. I recently installed a new HEI tach drive distributor which probably won't make much of a difference.

I'm guessing I want to get 202 intake 160 exhaust to get better flow. The stock heads are 75.47cc so a smaller combustion chamber of maybe 64cc would up the compression and add some decent horsepower. I honestly don't know what the exhaust runners are for. Any info on this? I'm about to order some headers to reduce any bottlenecks in the exhaust system. I'm running straight pipes back to resonators.

What would be the best brand of headers for a resonable price? I'm wanting to get into the 350 HP range. My stock LM1 is only around 160-170 HP. I've heard votec heads are pretty good, but I already have an intake and valve covers and carb and don't really want to buy new ones. Also, would I need a more aggressive cam for heads in this range?

Thanks for any help.
 

eoseitz

Well-known member
Joined
Sep 22, 2009
Messages
154
Location
Marion, OH
Corvette
1974 Stingray L82
Ok I did some more research and I think I understand the intake/exhaust runner concept now. For the exhaust it's the space the exhaust gas travels until it reaches the exhaust manifold? The intake/exhaust valve are how big around the valve are obviously. The bigger they are the more air/exhaust can go through. The combustion chamber is where the air/gas flames and causes compression on the pistons. Some would smaller intake/exhaust runners be better. I'm guessing smaller ones would be better for high rpm power such as sports cars? Larger ones would be better for trucks that need low end power, because it takes the air longer to move through them?
 

Crimson Thunder

Well-known member
Joined
Dec 16, 2001
Messages
814
Location
Orange Park FL USA
Corvette
1970 Marboro Maroon Convertible
Definitely consider a 64 cc combustion chamber as that Camaro motor probably has dished pistons. Stay away from any head that has an intake port larger than 190cc. For a cam,look for something with an intake duration at .050 around 218 degrees. Best to call your favorite cam company to get a recommendation.
 

TimAT

Well-known member
Joined
Sep 8, 2007
Messages
708
Location
Gladstone Missouri
Corvette
1969 LS-7 BB
When you start getting into port sizes things can get interesting. A small to medium port (intake) will flow faster(port velocity) than a larger port, but since it physically cannot get more air thru it, it will limit top RPM. On the flip side of that, the smaller ports will produce great torque at a lower RPM. TO get the selection correct, you have to be totally honest with yourself. IF you're planning on making big power at high RPM, then you'll need bigger ports. Big ports at low RPM and there's not much torque until you start getting the RPM up.
 

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