The Horsepower Specifications of a 1977 Chevy C10 350 4 Bolt Main Engineby Richard Rowe
Chevrolet and GMC's C/K ("C" for two-wheel-drive and "K" for four-wheel-drive) truck line is one of the longest running in automotive history. Produced continuously from 1960 through 1999 in America, C/K trucks range from basic haulers to four-wheel-drive muscle cars with beds. The C/K's third generation is its most definitive, spanning from 1973 through 1991 with very few changes throughout.
The four-bolt main 350 with two-barrel carburetor came with 8.5:1 compression, and was good for 145 horsepower at 3,800 rpm and 250 foot-pounds of torque at 2,200 rpm. 350s equipped with four-barrel Quadrajet carburetors produced 170 horsepower at 3,800 rpm and 255 foot-pounds of torque at 2,800 rpm.
The small-block Chevy's near 50-year production run has helped to make it one of the cheapest and easiest-to-modify V8 engines in history. If you're going to rebuild your '70s-spec 350, a mild performance rebuild probably won't cost you any more than a numbers-matching stock rebuild. Start by installing a camshaft with about 210 degrees of duration at 0.050-inch lift. Cap the engine with a mild double-plenum intake manifold optimized for torque and a rebuilt 450 cfm Quadrajet carburetor. Evacuate gases with a set of long-tube, "Tri-Y" headers to boost torque, and you'll end up with a street-friendly 350 that does its best work from idle to about 6,000 rpm. Expect about 310 horsepower and 370 foot-pounds of torque.
The cylinder heads used on '70s-era 350s were among the worst ever produced for this engine, so don't expect to make any real power using them. GM offers a truly budget solution with its factory-replacement Vortec heads, which (after a little bit of porting work) can produce well over 400 horsepower. The Vortec heads not only flow far better than the stock units, their slightly smaller combustion chambers (64-cc vs the stock 76-cc) will bump your compression up to a more reasonable 8.8:1. Combine the Vortec heads with an aftermarket carbureted manifold, 1 3/4-inch primary headers, and a cam with at least 225 degrees of duration at 0.050 lift and you should see an easy 450 horsepower at the flywheel. While not earth-shattering, 450 horsepower isn't bad considering that the engine still uses the stock low-compression pistons.
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