Jerry....I run mostly 12x4, 11x5's on my 46's but I have experimented with all sizes and the 12x4's and 11x5's are the best for the flying that I do. I have been runnings 46's for about 22 years and never run them lean. I think what happened the other day was the cold humid air because the next day it was cool ad dry so the engine turned up then. This was my first experience with the heavy spinner and it seems you guys are right...It doesn't change the rpm much at all.