Originally posted by BigTruckDriver
I don't know so I am asking,Can you use a thicker head gasket and lower compression?
Yes you can, but you will alter the piston to head clearance (squish) at the same time. Also called "quench", this is the calculated distance between the top of the piston and the bottom of the cylinder head at top dead center. It has been found that if this distance is minimized to a distance just short of allowing a piston/head collision, that the motor will become more detonation resistant and can be run on lower octane fuels and with more spark lead. A generally respected figure is 0.040", although some will tell you that you can run closer and some will tell you that you have to run a little wider than that. My personal opinion is that with lightweight steel rods and light pistons and keeping the rpm's in check, a guy can get away with much closer.

What you want to do when you build a motor is to pick your pistons and cylinder heads to establish your static compression ratio, then pick the right thickness of gasket to set the squish at around 0.040". An iron head motor can run as high as 11.0:1 on pump gas with a tight squish.

So you see, if you, for instance, changed an 0.040" gasket for one with a 0.060" thickness, yes you would lower the c.r., but you'd be going the wrong way to control detonation (the reason for changing the gasket in the first place).

the very last thing you pick is the camshaft, after you have dialed in the rear gear, tire size, converter and all the above.