In part 2, we discussed how family characteristics would make an engine react differently to modifications. As an introduction to this part, we will go back to 1970 to review two road tests in the April, 1970 issue of “Car Life” magazine. These tests show how engines from the same manufacturer react with “high performance” modifications. “Car Life” tested two new GTO’s; One was a Ram Air 400 rated at 366 HP @ 5100, 445 ~ torque @ 3600, with 4 speed, 4.10 gear, PS, and PB. The other was a 455 rated at 360 HP @ 4300, 500 # torque @ 2700, with automatic, 3.55 gear, PS, PB, and air conditioning. Following are some pertinent excerpts from the “Car Life” article pertaining to the engines/performance of each. Read more

Static compression, (C.R.) on a Pontiac is a function of the chamber volume and the engine displacement. If the chamber volume is increased, the C.R. goes down; if the displacement is increased, the C.R. goes up.

Following is a listing of the chamber volume in cubic centimeters (cc) of selected Pontiac heads used from 1966 to 1979. Read more

I’m always trying to improve the quarter-mile performance of my 1971 455 LeMans wagon, while retaining derivability, a 3.55:1 axle ratio, and a 5,500-rpm shift point. I recently tried several custom-ground cams, and I want to share the results with you. Read more

We have found that certain modifications to the rear suspension on all A Body cars will cause wheel hop during hard acceleration. The use of air shocks or booster shocks (small springs mounted around the shocks) will almost always cause a wheel hop problem. These two devices keep the rear axle assembly from rotating through its normal arc under acceleration. The result is wheel bounce, and if not stopped immediately, broken transmission cases, U-joints, or rear axle assemblies can be expected. Read more