You’ve got questions. We’ve got the answers—Mondays when the Summit Racing tech department tackles your automotive-related conundrums. This week, we help a Chevrolet 350-powered 1972 Camaro go to the next level with some street/strip upgrades.
J.C. Alda, NE
Q: I’m the proud owner of a 1972 Chevy Camaro. It’s motivated by a mostly stock 350 engine with headers, a Holley dual-plane aluminum intake manifold, 600 cfm Edelbrock carburetor, ACCEL HEI distributor, and 5-inch tall K&N air filter with an Extreme Air Flow top plate and K&N Stub Stack. The engine is backed by a TH-350 transmission and a 10-bolt differential. I drive it mostly on the street, but sometimes take it to the track.
Would installing a set of 305 heads improve performance and raise the compression ratio (stock is 8.0:1)? How big a cam can I use with the parts I already have?
The car runs great but isn’t very fast, and I’m tired of getting my butt kicked every time I race it. Do you think steeper gears will help me off the line? If I change the cam and gears, will I have to use a higher stall torque converter? How can I tell if I have an 8.2 or 8.5-inch rear-end?
A: World Products S/R 305 heads not only flow a lot more cfm than stock, but they’ll also raise your compression ratio, too. The heads feature 58cc combustion chambers and have 1.94-inch/1.50-inch valves for better low to midrange torque and horsepower–perfect for street-driven vehicles like yours.
Assuming the differential is stock, you’ve got an 8.5-inch 10-bolt under the rear bumper of your car. The easy way to tell is by examining the ring gear bolts. The 8.2-inch diff uses 3/8-inch right-hand thread bolts to hold the ring gear to the carrier; 8.5-inch axles use 7/16-inch bolts with left-hand threads.