Jan, I may have a couple years on ya. My first Q-500 race was in 1979. No worries, we can't all agree all of the time. I beleive there is some merit to what you are saying but IMO what you are refering to is a symtom of what is happening and not the actual cause. I agree that he is not able to lean the engine to optimum fuel/air ratio but I feel it is because of the pre-ignition. As he leans the needle the cylinder temps go up, the engine pre-ignites and sags so he does have to run rich. Yes this contributes to the low RPM figures. The fix is to lower the cylinder temps via less load and lower plug temp. This will make the engine fire at the correct time allowing him to lean to the optimum air/fuel mix and get the engine into it's correct powerband. This is provided someone has left the stock head gasket in place. We have all seen guys that remove head gaskets thinking it will lead to more power and then wonder why they burned up a piston and liner.