340 with edelbrock heads overheating

StreetSleeper said
Rusty I have a couple of questions about this.
Generically, would 12 degrees of initial timing be about right?

Second, if he has closed chambered heads, wouldn’t those be more efficient and need less timing? Initial or total?

He didn’t mention if he has 340-specific-edelbrock open chamber heads.

Does the aluminum affect timing?

I would have thought more efficient heads need less timing. Thanks for your wisdom!!

@RustyRatRod
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More "efficient" heads don't necessarily need less timing. An engine that has a high cylinder pressure is the one that will require less timing. There may be "some" truth to the more efficient head, but all in all it's more linked to cylinder pressure. Notice I did not say compression ratio. Cylinder pressure and compression ratio are not the same.