I have the same engine and prop. Do you know what your needle settings are? I get about 6900 on a Menz 22x8. I think my high needle is rich. I'm at 1 3/4 high, 1 3/4 low.
ORIGINAL: Angus Balfour
ZDZ 50NG, ~3 gallons through it, oil 40:1. Menz-S 22X8 @7500rpm