2 different carbs and other tuning changes and the same intermittent issue, both too fast too much pump shot? At one point the demon was screamin'. All in @ 2200 seems too fast a curve, but you said it had run fine there. Ignition boxes can act stupid and random when they're on their way out. Running a little fat can create some exhaust popping, not normally a muffler hand grenade case splitting backfire(?), but a sticking valve, or raw gas could. Give the engine what it wants, some like 38-40 or the ring has slipped, and the timing is still late. But the plug read, and where's Mark? And like stated,go back in time to the setup before the hold harmless for the dyno run.
But I'm really thinking it could be the rise time on the coil because it seems to happen during a call for acceleration, no? And back to the ignition box again we go. Heat soak or not?
