Hi Ted Tks for the reply.I didn't think that it was the new cam because the leakdown test showed 170# in each cyl and didn't lose any so I ruled it out and the engine runs perfectly up until the problem starts.I've had 2 different intakes on it ,2different ignitions on it ,mallory Hy Fire and a new oem ignition,5 different carbs and loosened the rocker arm shafts 1/4 turn at a time up to one full turn with no change,regsapped the trigger two different times,disconnected one carb on the duel carb setup with no change.I've not been able to make it run better or worse.Nothing seems to make a difference..John(shadyj)