[tubman]

.045"-.050" for piston crown to head, and .060 over the valves (I don't run wild cams and have never even been close over the valves). For a street engine, I like to be on the high side. In addition to increasing the compression ratio, it promotes better combustion of the fuel/air mixture because it optimizes the "squish" area above the piston. For more detail, there are many threads, both on here and on the H.A.M.B. An increase in compression is always helpful in increasing performance AND fuel economy. Given today's fuels, we shouldn't be constrained to the stock Ford compression ratios, that were 7.2:1 at their best. May be the restoration guys would like to, but if you actually drive your cars, It's the way to go.