Whats the cam installed at... back it off a couple
degrees so it would have less compression(the piston
would be higher in the cyl).. if your like the rest
of us we tend to advance them at least 4* or more for
more low end

I had a 451 low deck with kb quench dome pistons and 452 heads a 223 230 at 50 cam that had 10.6 compression. It ran on pump gas on all but the hottest days. When the weather was 90+ I would add 2-3 gallons race gas. Quench was .038

I ran 10.2.1 iron headed 451 with a 284xe juice cam for 16 years no issue with an auto and loose converter. Swapped to a manual and ping city. Colder plugs and 33 total quieted it down but lost power for sure.

I would use different gaskets & shoot for .035" quench (to get EFFICIENT quench). & precision measuring as in my exp listed gasket thicknesses (compressed and uncompressed) can be a mile off (10-15 tho is a mile off). But on the Q at hand I ain't optomistic on avoiding quench (gas is crap & getting worse). post what you go with & how it turns out

That locked distributor isn't doing you any favors for either combo on a hi-compression street car.

If it was me and the heads are on the shelf ready to go, I'm picking a head gasket that gives me the tightest quench and still keeps the piston from smacking the head and going for it.

It already rattles so if there is no improvement on that front you're out a set of gaskets and some time but with quench you might be able to tune around it and gain a few ponies to boot.

Kevin

I agree with changing to a distributor you can set up with less initial, and ramp in total to match the motor. Also, anything you can do to cool the intake charge will help, obviously. Since you plan on a better motor soon, you might as well just work with the 906 heads for now, unless you want to know just how much the closed chamber heads will change things.

lets see... timing backed off a little helped. So if you had a curve to the timing you could take out as much as you want at that problem rpm/area. problem solved....with the closed chamber heads just my

Chip it can't be any worse than it is... do it ...

I did a KB quench piston motor for a friend a number of years ago, it was an identical build as another KB piston motor another friend had , the only difference was one motor had the quench number at no more than .045, the other motor was .050 plus.

The tight motor had 10.3 compression, the loose one was 9.5. The tight motor ran fine on 93 octane from the pump, the 9.5 motor would ping if the owner ran anything lower than 93, i would have expected 89 to be ok.