Big-Block Power Tune

It is surprising how often a neglected PCV valve goes unnoticed, creating problems such as a rough idle, plug fouling, oil burning, exhaust smoke, and erratic engine operation. Replacement is quick and easy.

One of the best things you can do for your classic Corvette is invest in a competent dyno tune. The information gathered will help identify any problems and point the direction for the cure. Here, Westech's Steve Abbruzzese securely strapped the Vette to the chassis dyno's power-measuring rollers.

A key instrument for data gathering is a wide-band lambda tester, which can quickly and accurately read the engine's air/fuel ratio. The arrangement here uses a remote sensor apparatus, with a probe going into the factory sidepipes.

At the Westech dyno, information gathered from the wide-band lambda is fed into a display unit, showing air/fuel ratio; it is also fed into and recorded by the dyno computer. Here we have a crisp 13.6:1 at a 750-rpm idle.

The Holley carburetors fitted as original equipment to big-block Corvettes are sensitive to the fuel level in the float bowls. Before any tuning is done, the float level should be checked and adjusted as necessary.

Before any power pulls are done, the base carb adjustments are made, starting with the engine idle speed and mixture, which are simply adjusted via the idle mixture and idle speed screws. The accurate tach and lambda on the dyno ensure a perfect, true setting.