My AMC 232 was long overdue for a valve job at 250,000 miles. It's a 1970 head, a wedge design with no squish space. It doesn't allow much spark advance, and it likes to ping.
I have a '64 head, nearly identical, but it has a 56cc chamber and decent squish. (AMC went back to a squish design mid 70's I think, just a few years with the open chamber).
I've got 199ci flat-top pistons (instead of stock dished). The tops come to approx. 0.084" of the deck; with a .030" headgasket it gives me about 9.2:1 compression, with .114" of squish.
* Is .114" too much for squish space, am I just asking for detonation?
* Is 9.2:1 tolerable under this circumstance?
The only other choice is the open chamber, zero squish. It ran for 20 years, so it can't be that bad, but it wouldn't take much advance.
This is otherwise a stock motor, the cylinders are perfect, it was balanced when built, and static compression was 160 psi, one at 150 one at 170. It ran on LP only for 20 years and got synth oil exclusively so it's otherwise mechanically perfect.
