[Dangerous Doug]

I'm picturing using modeling clay, water, and a graduated cylinder. Is that what you had in mind?

I haven't purchased heads yet (though, a stock pair came with the engine) so I do have some flexiblity in the chamber size, restricted, of course, by what is readily available on the market.

What's the calculation? I figure the ratio of cylindrical volumes, V1 being the chamber volume with the piston at the bottom of the chamber, and V2 being the chamber volume with the piston at the top of it's stroke? (V1-V2)/V2?