I know by experience on three engines I assembled that a zero quench distance works to lower operating temperature of the engine.
A zero piston/deck quench distance with Fel Pro head gasket with .039" crushed thickness resulted in 20 degree reduction in operating temperature on three 455 Pontiac engines using 105 octane VP C-12 racing fuel. . My engine builder CNC machined the deck on all three engines about .030" to achieve a zero piston/deck height.
My associate's 428 Pontiac Bonneville ran 30 - 40 degrees hotter after he machined the piston tops 0.125" like a pieces of baloney in a futile attempt to run 93 octane pump gas. His piston/deck quench distance was about .155" plus .039" crushed head gaskets. He could not load the motor without severe pre-ignitioneven on 105 octane VP racing fuel. If he had dished the pistons 2.00" O.D. x .200" deep leaving 1.00" quench perimeter around the top of the piston, the engine would have run on kool-aid quality pump gas at 190 degrees on a 110 degree day. .
Last edited by MouseFink; 11-26-2012 at 05:41 PM.