Looking up thermal expansion values for whatever material, and just doing the numbers should get you close.
Back in the late 80s when I replaced those close to 2"OD valve seats in an 8 liter straight six Scania diesel, I did that before even trying. I put those cast iron heads in an electric oven, cranked it up to max, and cooled the new valve seats with CO2/ dry ice.
IIRC, they were close to 0.10 mm or 4/1000" larger than the bore in the head.....
Back in the late 80s when I replaced those close to 2"OD valve seats in an 8 liter straight six Scania diesel, I did that before even trying. I put those cast iron heads in an electric oven, cranked it up to max, and cooled the new valve seats with CO2/ dry ice.
IIRC, they were close to 0.10 mm or 4/1000" larger than the bore in the head.....
