Jim I have never heard of an engine quitting due to detonation by itself. If the engine quits is is usually due to the engine damage done by the detonation, not the detonation itself, if that makes sense. Most often the damage is to the crown of the psiton, since detonation is usually accompanied by a rocking of the piston back and forth on the wrist pin, causing a "slapping" of the piston into the cylinder walls. This is where the damage occurs, usually breaking some portion of the crown of the piston off and either sending the piece out the exhaust, which sometimes also damages the exhaust valve, or sending it into the oil pan. A quick compression check can easily discover a damaged cylinder. This damage can also happen and the engine still operate, possibly with decent power as Mark Jones found when he crushed the ring lands on one of his pistons. It is possible for your mixture to be too rich for the temp you were seeing, since you were on the upper end of the temp range, and at full rich would probably smother a standard set of plugs, which with that heat would dry themselves.
In engine diagnostics, we always went back to basics whenever we were trying to determine and engine failure: 1) check fuel supply; 2) check ignition capability - good spark; 3) check compression. Those are your three basics. Without them in the right order, all else you check is worthless. Once you determine these are right and in the correct order, then the ghost hunt can begin. Worked for me for over 15 years.... Colin N96TA
