I'll tell you a simple metric I use to determine combustion chamber efficiency.
How much total timing does it take when your have your **** correct.
Not the clowns who run a plug two ranges too hot, then drown the plug with fuel to cool it. Not the goons who don't think before they build and don't have enough gear, converter and a cam they picked out of a book.
I'm talking about a correctly assembled combination.
Any early SBC head with its horrible plug location that doesn't run on 42 total has an issue. And that's a quench chamber head.
A conventional BBC needs 38-40 total or something else is wrong. It has quench.
BBM has a head with garbage plug location. It needs 38-40 total. Doesn't matter if the head has quench or not.
A SBM, which has a plug location about as good as you can get for a conventional wedge will run with 35-36 total or something is wrong. That is a head without quench.
A Hemi, which doesn't have quench will normally run ar 32-34 total.
My point is plug location is much more important that quench or chamber shape.
