[Gasser Nate]

Check the flywheel nut. Mine was loctited but was not done up tight against the flywheel. There was also a recall on the right hand crank nut.
Failing that you may have too much compression and need some head modifications. Mine was knocking under load slightly no matter how it was jetted. The head was machined to lower the squish and drop as much compression as possible. Smooth predictable power now with next to no spooge.