i put a reconditioned 3247 on my 66. i was running a avenger 770 and really liked it. being a bit of a "purist" i was compelled to put on the 3247 in preparation to driving to carlisle,over 450 miles one way.i found it to stumble and rejetted with 72 jets as oposed to the factory 70 and the stumble went away. did they have to do this at the dealer when new? also should i up the secodary jets as well? i am running 104 avgas.