LOL ... Remember the Weber tuning posts in this thread? The only way I was able to reduce the lean transition from the idle circuit to the main circuit was to run the idle circuit at 11.5:1 or richer. That means 95% of the time the engine was running pig rich. 12-13 MPG. That is why I seriously doubt there was any detonation problem. That rich means a cool/slow combustion cycle. The EFI conversion is aimed at curing the tuning.Piledriver wrote: OTOH, the one on #3 probably "kissed" the head when the #3 rod bearing died, and knocked off the carbon there.
(The sharp "edge"/transition gives that away, usually there's a narrow but gradual transition area)
Also, you are running too rich to have that much carbon build up that soon.
One option you have at this point is to use Mahle "B" (78-82mm stroker) pistons with longer H-beam rods.
If you intend it to run over 7K, that is a very good plan.
Tech information is hard to come by. The case is machined to 97mm for the spigots and the Heads are machined to 101mm for the top of the cylinders (AA Thick Wall 92's) This is the same as the 94mm cylinders.
I can reuse the cylinders with other pistons to maintain and have them honed to get the right clearances if they are too small for 92mm Mahles. If they are too big, I'm hooped. From what I've found online It seems that the Mahle P&C combos are thin wall so they would be a too loose fit in the case and heads?
I have 5.394" rods now. What length would I need to use 'B" pistons?
Here are the other piston tops and the skirt of the #1 piston. #1 is the only hole that had the coating gone by the wrist pin hole.