The issue was that the small-block Chevy was designed to be cast iron, not aluminum. While the aluminum 377 was struggling, work began to replace it with the W-Series 348/407/427 truck engine.

Q: Greg, you’ve mentioned the Mystery 427 Chevy engine in previous columns and I’m still confused. What really was the Mystery 427, and was it the same as the Z-11 that the drag racers ran?

During that model year, Chevy introduced a new 427-ci (7.0-liter) version of its Mark IV big block, dubbed Turbo-Jet. Initially, it was available in two output configurations, with the most lethal ...