First engine build question

MOPAROFFICIAL said

Where does one learn such rule?

Nothing less than, perhaps.
@ 8.88889 seems to be the max near sea level with some quench. He has none "to my knowledge" so anything under 8.1 would be absolutely safe, basing that on my repeated experience.
My .030 kb hyoer 340 ran 160psi @9.5 compression 69cc heads pistons and around .020 out of the hole. Valve closed iirr 58*

In other words 130-140 PSI is kind of like stock territory... we need to be 150 or better if we're really trying to build any kind of performance or even stock performance motor.

There are engines out there that dont fit the above, but we'll stick to this 340 for now.

Click to expand...

Why 150 or better? You can take a stone stock engine and add bolt ons and add a good bit, you know that. Good intake, carburetor, headers and distributor you can adjust mechanical advance on. Come on man, he's not building something to go racing here. He may not have the budget to do what you're talkin about. I haven't read every post, so maybe he does, but I try to approach it like someone is on a budget until they say otherwise.

I completely do agree with you though that if his budget allows he should get cylinder pressure up there. Does he have to? Not in my opinion.

And where did I learn that rule? Trial and error doin stupid **** as a kid.