Piston recommendation
If anyone can enlighten me on the subject, I'd love it.
There is a sticky on quench in the General Discussion subforum. In a nutshell, it is any tight fit between the piston top and the adjacent area in the combustion chamber wall. Tight fit means under .060" maximum and preferably .035" to .050", measured (or accurately computed and checked) at TDC. The tighter the better, but too tight results in pistons kissing the head....the .035" minimum gap is a good general rule of thumb for that.
When the piston reaches TDC at the top of the combustion cycle, the ignition process has already started, and the tight quench gap compresses and 'squirts' the mixture out of that gap into the rest of the combustion chamber. That action swirls the mixture and makes for more complete and faster burning of the mixture, increasing efficiency and reducing the probability of detonation. It is a known tactic for lowering detonation. We focused a lot of effort on a .040" quench gap on our current 340 build, just for this reason.
FWIW, this type of effect, result from combustion chamber shaping, was preliminarily identified back in the 1920's in a seminal research paper in England on aircraft engines. It was a known factor for car engines by the 1960's.
And out of politeness, I have not asked about the oiling, but now that the ice has been broken....I'll admit to a strong curiosity on that point.
