I was playing around with the compression ratio calculator over at Butler Performance.
If I have an unmolested block, what would the deck height be? The calculator told me if I had 0.090†deck and used a gasket that crushed to 0.045†that my CR would fall right in around 9.5:1 using the 62 heads. Is there any down side to having a slight deck height and basically flat top pistons?
I've read that the factory deck height ranged from around .010 to .023., and even more, depending on who you believe.
You want around .040 quench distance. No more than .045. The quench distance is the distance from the flat part of the piston top, @ TDC, to the head. So, a zero deck height piston + a .045 thick head gasket would give you .045 quench distance. Or, if you use the higher priced FP #1016 head gaskets, they are .039 thick. So, if using these you'd get that same.045 quench distance, with .006 deck height pistons. Would be better to use the .039 gaskets & zero deck height, for .039 quench. The smaller quench distance helps prevent detonation.
So, I'd consider the quench distance more important than trying to get the max CR you can get by with. Obviously, I'm talkin about pump gas street engines. If you're gonna race, with high octane gas, run all the CR you want.
I wouldn't wanna run a piston .090 in the hole, in any normal Pontiac street engine. The best way to reduce CR is with bigger chambers in the heads, or dish pistons, NOT by more deck height.
As soon as you say something won't work, somebody will post that it worked very well for them, for many years, with no problems at all. So, you'll just have to decide what to believe & what to not believe.
