[E4ODnut]

To the best of my knowledge, EGTs are maximum at stoich and decrease either side of. I have EGT instruments on my engines. The ones on the boat are accurate to 4 degrees F. My observations don't show any increase in EGT with lean mix.

At light loads your timing would probably have to be advanced to the point where your power would fall off before you would be anywhere near any danger of detonation and holing a piston. The engine simply isn't making enough power to hurt itself at those settings. I've experimented quite a bit with timing and that was my observation. You can retard the timing if you like, but all that will do will decrease your efficiency and raise the EGT a bit.

As I mentioned before, my instruments confirm better economy at mixtures leaner than stoich, but, in all fairness, these are on my engines with my tuning methods. Your's might not agree.

It's entirely possible that mixtures leaner than ~16:1 wouldn't get any better economy. I've found it almost impossible to set things that fine over a reasonable cruising range and the indicated mix ranges from about 15.5 to about 18 or so. It's beyond my capability to determine exactly where optimum is and maintain it.