We’ve got the answers—the Summit Racing tech department tackles your automotive-related conundrums. This week, we’re taming an old race engine for street use.
R.F . • Morgan, GA
Q: I plan to install the stroker motor from my former race car into my recently purchased 1970 Camaro. The engine is a 4-bolt main, GM 350 that’s bored .060 inches over and makes 11:1 compression. It has World Sportsman II iron heads, forged pistons, a .623-inch/.623-inch intake/exhaust roller cam, MSD 6AL ignition box, and a Holley 850 cfm double-pumper carb. The Camaro has a Turbo 350 transmission with a shift kit and a 3,500 rpm stall converter driving a 10-bolt posi rear-end and 3.73 gears. The car won’t be a daily driver, but I plan on driving it on weekends and to the occasional cruise-in as well. I used to run 110 octane when I raced. How much timing detuning would you recommend for street use and would it be possible to run 93 octane gas in this combo?
A: It sounds like you’ve built an awesome race engine, but you’ve got too much cam and compression to run 93 octane gas. Plus, your 3.73 gear will cause your 3,500 rpm stall converter to slip under normal street conditions and hurt your mileage more than your big carburetor. To improve your mileage, lower your cam, compression (9.5:1 or less), and stall speed (to 2,500 rpm) and then you can use a smaller carburetor and pump gas.