um nope ive done the measurements myself on a 20R and a 22R head, the combustion was almost 10 cc's difference
mine is a 81 block and 80 20 head, with my cam i had to notch the pistons .180
i just held each one up to the head, marked with a marker where the valve would touch then notched, so as not to loose anymore material than i had to
laser block and 20 head would be like 12:1 this was what i meant in my first reply
Kyle the numbers on compression for adding the 20R head came from toysport and Marlin
with careful measurements on the bench my calculations of cr on my engine are 9.7 to 1
the only mod i did to the bowl of the combustion chamber was to smooth the edge of the head to prevent premature detonation
