Good input!

Also Pat, if you really want to get all technical, get a small Perspex disc just bigger than the cylinder bore, drill a hole in the middle and stick it to the top of the block with the piston at TDC / the face of the head etc with a smear of grease to seal it.

Get a syringe and pump oil in through the hole. This will give you a near exact CC measure of how much fluid can occupy the available space.

Factor that against the total displacement area of the piston, and you can pretty accurately calculate the compression ratio from an empty cylinder to a full cylinder.

You can then start working out how many thou off the head will get you what ratio and so on, working in the thickness of a gasket etc etc.

I've not seen any info on what a difference the compression ratio will make on a 3VZ, but going by old school engine stuff, the results can be quite impressive.

C.