The other thread was getting pretty long, but here it is for those that didn't see it. http://www.rcuniverse.com/forum/m_24..._1/key_/tm.htm

Yesterday I ran the engine the first time since making some changes. First I installed a new tank, 10x6 prop instead of a 10x7, new needle valve to replace the pitted one, new head gasket and new backplate o-ring. I also bought a tachometer to get some actual numbers.

Started it up and ran it and adjusted the needle valve to a rich sound and turning 12,500 rpm. First thing I noticed was how much more responsive the engine is with the 10x6 compared to the 10x7. After a while running, the engine picked up 2000 rpm and was running at 14,500 rpm towards the end of the tank. Changing nothing, I stopped the engine and refueled. It then tached at 12,500 again. So, it appears that if I tach the engine on the ground at 12.5K I can compensate for the leaning out towards the end of the tank.

Is it normal for an engine to gain 2000 rpm?

I then ran the engine again and tached it at 12000 rpm, then the max it ever hit during that run was 14000 which keeps it from over leaning. Max rpm I saw was 14,600 with the 10x6 Master Airscrew running on Cool Power 15%.

I also played with the low speed mix. sure enough it DOES affect the high speed needle setting as several mentioned in the old post. I richened the low speed needle until the engine would slowly load up and die. I then leaned it until it would idle for an extended period of time yet still throttle up relatively clean. I think I'm ready for a test flight.

MIke