It looks like finding a good ring pack for the stock 4.46 bore is a pita, so may as well punch it out to 4.5 bore, and my biggest question is upping my CR a good idea for 91 pump gas? I’m switching out the ZZ502 cam for the 168731 can which should bleed off a little more pressure, and SRP makes a -10cc piston that was made for the Edelbrock heads. It looks even if I deck the block .010 I should be at 10.25:1 at most, and that’s not including the bore notching and the fact that the Edelbrock heads tend to measure out closer 113cc according to the internet. Thoughts?

stock GM 4bolt 9.8 block
edelbrock Rpm Performer oval heads (advertised 110cc chambers)
Victor Jr intake
QF850m carb
Crane 731 cam
SRP pistons w/moly too ring
https://www.summitracing.com/parts/srp-212161-8

Bore notch is about 1 cc give or take. I'm on way out the door but shouldn't you have not used -neg for piston volume. Just put in 10?

If you can find the cam card valve (timing events) for the zz cam post it. Also I may have mis read your first post with your piston being dome or dish. I can ck comp calculator also when I get back.

The Summit calc considers the area displaced by the dome, so a dish would be a + number. The stock piston a 1cc done and the replacements that I’m looking at are 10cc domes.

Adding a cc for the bore notch and the .051 brings it down to a fair enough level. What is a general rule of thumb for the highest CR that you’d be comfortable with on a N/A engine w/Al heads?

Looking through the old threads of the same question it looks to be prudent to keep it 9.8:1 and 34* max timing.