The Vortec uses 64-cc combustion chambers, which are substantially smaller than the traditional 76-cc chamber found on most post-’60s small-block Chevy heads. The valve sizes are 1.94/1.50-inch ...

Flathead designs gave way to overhead valves, and inline cylinder ... tested a twin-turbocharged 4200 Vortec with 400 horsepower concept-engine placed in a Chevy Trailblazer as a show of force ...