340 with edelbrock heads overheating

autoxcuda said
Why isn’t the compression ratio change between X-heads and edelbrocks being addressed?

He could be detonating and not hearing it.

If he was at 8.88 before he likely would be at 9.88 now.

Aluminum heads are more resistant to detonation than iron and therefore they can typically be run at higher compression than iron. I don’t know how good the gas is where the OP is, but I’ll bet the increased compression is not the issue.