Still waiting on the OTTP Main Bolt replacements in the mail, so I thought I'd do something more fun - calculating compression ration. Being that I am using flat top 10:1 pistons, the math is fairly easy. The hardest part is getting the volume of the combustion chamber. To do this, I measured by volume and weight of water. I coated the backside of the valves in vasoline, and then put a piece of plexiglass down on top of it (again sealed with vasoline) to seal the chamber. Using a liquid syringe and scale, I was able to get within 0.5 ml of the combustion chamber volume.
This isn't 100% accurate, but I would like to think its more of a "worse case scenario". All numbers have purposely leaned that direction before any calculations. Technically I should be using thick plexiglass so it doesn't bow in the middle. I didn't want to pay for it, so I just used what I had on hand. This likely upped my compression ratio calculations, but that's ok. As I said, worst case scenario.
Here are the results:
The only magic constant I have is the stock head volume. I don't know this number because I didn't measure before the head was refreshed. The deck offset is how much was skimmed off the block. This is not 100% known, but should be around there. I'm fairly happy. I went with the 0.060" Cometic gasket. This tells me my compression ratio will be at or below the stock 10:1, which is what I was really aiming for.