Nothing conjures up images of power and heritage like a Tri-power 427. This package in a Corvette is responsible for much of the respect and admiration that keeps the prices of 427 Corvettes beyond the reach of many. This financial hurdle, coupled with the errant view that these engines aren’t capable of keeping their cool, have relegated these powerful engines to only those who can “put up with them.” With the help of Chris Petris from the Corvette Clinic, we’ll take on the task of building a modern-day, Tri-power 427 that will keep its cool and have as much power on tap as when the General was building them. We’re assembling this engine for a driver, so the exact part and casting numbers will not be an issue. This will be a multi-part story, from the acquisition of the hard parts and what to look for, to finishing up with the compilation of the parts.

The General referred to the big-block engines built between 1965 and 1990 as the Mark IV (Four) family of engines. They were replaced in 1991 by the new generation of big-blocks titled Mark Five or GEN V. The earlier Mark IV engine blocks were offered in two- or four-bolt main caps, while the GEN V all have four-bolt mains. Interchangeability of the front four-main caps is possible if they’re align-bored, but the rear cap will not interchange because the GEN V uses a one-piece rear-main seal instead of the two-piece used in the Mark IV. We’ll be dealing only with the Mark IV engines in this story. Chris has been acquiring parts for this engine for some time and we wanted to show our readers what to look for when undertaking such a task.

The Pocket Code Manuals/SUMMIT RACING
P.O. Box 909
OH  44309-0909
Corvette Clinic
Chevrolet by the Numbers/Robert Bentley Publishers
1033 Massachusetts Ave.
MA  02138