When people ask about rebuilding 305 Chevys, our usual response is "Scrap it-it costs the same to rebuild a 350 and you'll make more power." We'll stick with that opinion for rebuilds. But what about all the good-running 305s in millions of cars and trucks? And how about all those leftover 305s that can be had for nearly free anywhere in the country?
We had to know if easy bolt-on speed parts could save this dog of an engine for an affordable price. A friend gave us a free 80,000-mile 305 out of an '82 Camaro, so we trundled it to Westech's SuperFlow engine dyno and threw a bunch of parts at it. The results may surprise you-they did us.
With headers, a Q-Jet carb, and a stock cast-iron GM intake, the engine baselined at 197 h
"Nader" Of Performance
With 8.6:1 compression and a grossly mild hydraulic cam, a stock LG4 '82 Camaro 305 wheezed out 145 net hp at 4,000 rpm and only 165 lb-ft of torque at 4,200, as installed in the car complete with a catalytic converter. Mounted on Westech's dyno, ours breathed through headers and 3-inch dual pipes feeding Flowmaster mufflers. A noncomputer HEI with 22 degrees of advance in the distributor was used for this and all subsequent tests, and the engine was run on generic 89-octane gas. Carb calibration and initial lead was optimized as needed. In otherwise stock form, the engine made 197.3 dyno hp at 4,600 rpm, with 261.3 lb-ft of torque at 3,100. The headers were probably worth 30 hp, with the rest of the increase attributable to the differing net versus gross power correction factors.
Intakes, from left: We tried Edelbrock's Performer, Performer RPM Q-jet, and Victor Jr. on
We began by bolting on an Edelbrock Performer EGR intake but with the EGR blocked off. Up went the output: 216.6 hp at 4,200 rpm and 284.8 lb-ft of torque at 3,300-3,400 rpm. Peak power increased by 19.3 hp, and the rpm at peak dropped to a friendly 4,200 rpm from 4,600. Average power through the curve improved by 14.9 hp and 21.2 lb-ft.
In theory, the Performer is the hot choice with the wimp cam-but in this case, switching to an Edelbrock Performer RPM Q-jet manifold woke up the engine even more. Compared to the standard Performer, the RPM made equal or better numbers throughout most of the test range. The big gains occurred over 4,200 rpm, where the RPM churned out 15-20 more lb-ft and 10-20 more hp. Peak numbers for the RPM were 230.9 hp at 4,800 and 285.2 lb-ft at 3,300.
Make Room For Jr.
Against all practical advice, we tried Edelbrock's Victor Jr., a competition-style single-plane with an under-runner air gap. We tried it with both the Q-jet, which gave up some power and torque, and with a Holley 750-cfm double-pumper carb. The Victor Jr. with the Holley closely matched the Performer RPM with the Q-Jet through most of the rpm range, averaging less than 1 number difference overall. This was surprising, since the high-rise single-plane would usually be considered the worst possible choice for a stock 305. Even so-as in all previous tests-the engine idled with 20 inches of vacuum! Still, the Performer RPM would be a better choice on an otherwise stock engine because it has provisions for exhaust-manifold heat, accepts stock bracketry, and probably offers better low-rpm throttle response.
With the Victor Jr. and the 750 Holley looking good even with the stock cam, we decided the single-plane would be the smart move with a hotter cam. A 305 has 45 less cubic inches than a 350, so it requires conservative camshaft selection. Westech selected Comp Cam's dual-pattern XE262H-10 Xtreme Energy hydraulic flat-tappet profile. The choice was influenced by the desire to match the flow characteristics of the cylinder heads we planned to try later. In view of the future head swap, we retained the tired old valvesprings when testing with the stock heads.