I have been struggling to understand and determine the correct deck height target for my engine build. Wayne D's book references Walt at Competition Engineering with a 1.25mm to 1.50mm target using the hollowed out solder method. Wayne also says builders looking for higher compression go down to 1.00mm deck height. Then I researched through this forum and the early 911 registry forum and the consensus seems to be that deck height from the factory was set to 1.00mm, with the caveat that the various tolerances must be known and accounted for, and the valve to piston clearance must be checked and verified to be at or greater than the minimum (1.5mm intake & 2.0mm exhaust) thru the stroke of the piston approaching, at and falling away from top dead center on the overlapping stroke.
Anyway, that all got me to thinking about the compression ratio (CR) and the effects of deck height and shaved heads on the CR. So I started working on some calculations which I share below - please check my work:
I also calculated CR at deck height of 1.25mm (CR = 9.3) and 1.50mm (CR = 9.1) without the heads being shaved 0.25mm.