[neverfastenuff]

If your slugs are .010 in the hole and presently have .039 head gasket, how thin of a gasket could you go safely before valve to piston clearance? Is it even worth trying to get more compression this way? Thinking of trying .021 or.028 to gain a little. Pistons are 7cc dished valve reliefed. Thank you for your help.

[DoubleVision]

That depends on the cam timing and of course what size cam. If in any doubt do a mock up and check the clearences. If your not running a massive cam there`s not that much worry of piston to valve clearence. as said, it depends on a few varibles.

[techinspector1]

You mean valve to piston collision? It's hard to say because of all the variables involved. No two motor alike, particularly the heads. I wouldn't use this method to increase static compression ratio. Well, I might if I needed more static compression ratio to match up with a cam that is too big for the motor, but that should have been figured out when the motor was built. I might also use it to improve squish if my cylinder pressure was such that the motor rattled on the available fuel. The tightest I'd go on squish is 0.035". David Vizard runs em' there.

One full point of compression (for instance 9.0 to 10.0) will increase power 4%. If you're at 0.049" on the squish now, the tightest you could go is another 0.014"..... 0.014" on a 4.100" bore gasket is 3cc's. If you started with a motor that is 10.06:1 for instance, cutting 3cc's out of the equation would yield 10.42:1 and theoretically increase power about 1.3% (5.2 horsepower on a 400 hp motor)