You would need to set squish clearance as well as static cranking compression. The dial a domes allowed you to do this. Use soft solder pieces through spark plug holes then compress the solder. You measure squish clearance at edge of piston, between head an piston crown. Tighter squish equals higher compression and velocity during combustion.. Many factors go into what the proper distance is. Air temp, air density, fuel type, fuel octane, engine rpm, ignition timing, engine temp. All will change flame front speed, detonation timing and heat generated.
Squish clearance gives you a static reference point. Cranking compression is the other static reference point.
To build max power you have to factor in all of your specific conditions to build max power.
We would start with low compression say 110 cranking, and .085” squish clearance. Watch plugs and piston tops for signs of detonation. Dark brown is good. Powder black start of detonation, then gray, then white its melting.
Then decrease squish to .080” / 120 psi cranking compression then retest, check plugs. (Everything else being the same, fuel etc.)
If you are methodical you can build max power for the fuel type you have. Most didn’t know or have skills or patience to do this.
Engines melted, people get mad, money burned. PSI melted away, even though they were building wild and expensive stuff.
I remember the 1050cc sportster twin was $12,500, 25 years ago..
