Large rpm drop

Power valve was a known good one, ruling out a blown/bad power valve.

I'm running around that timing to keep from detonating on pump gas. I put this setup together last June, blew head gasket early July running ~34* total timing.
View attachment 1715465182
After that, milled the heads 0.010" to flatten, kept total timing 30* to play it safe. Initially assembled the engine with the rings on the tight side of kb's spec, butted rings in October and that's when I rebuilt it to how it is now. Detonation may have been a contributing factor to that as well. But idle always been an issue however no matter what iteration of the engine I was on.
View attachment 1715465193

Aluminum heads would probably help with detonation and will probably be used down the road if I can find a good deal, but for now closed chambered irons are what I have.

And this is a thread on getting idle adjustment right so let's save WOT for a later date.



Im Not questioning if the power valve is bad or not. I'm suggesting unless your cruise vacuum is 9 or 10 inches you are opening the power valve way too late.

There is not a scenario where I can say a 6.5 power valve is the correct one for any application.