Hi,
I have several Fox 74's and have made extensive use of the Flitelinesolutions website
info. Absolutely essential to change head button to their design. Pay very close attention
to what they say about the later carb, and the groove in the crankcase. I have one engine
with the groove in case that would not quit with the carb completely shut. I prefer the
older MkX carb, I feel it has better midrange control of the mixture. I run 15% nitro
and 18% Castor oil.
Good Luck,
Jim