Guy's, Didn't mean to mislead anyone. During the break in the tach showed as high as 7900 rpms. The engine ran consistantly at 7600 with the MA 18x10. Maybe the tach is off but that is what it showed consistantly. I am using a GlowBee tach. Haven't had a chance to try the MA 20x8 wood Schimatar. I think the Big Bore Walbro gives the engine more grunt. I am not looking for high rpm's. I want thrust and it seems I am getting it. Time will tell. I'll post the results when I start fooling around with the engine again. Right now, I am thrashing to finish my model in time for the WRAM show.