340 compression ratio

Steve,
My neighbor is an awesome engine builder. The other day I was in his shop and asked him what a tall thin glass beaker graduated in cc's was for. He said it was to check compression ratio's. it looked real fragile! I'm no expert for sure, but my understanding is you have to measure the volume of cc's in the cylinder with the head off, piston full down, and the cylinder level. Then measure cc's with the head on and piston full up through plug hole. That should give an exact ratio for particular engine. I can ask him exactly what he does if you're interested.