[Crankster]

While I'm no expert I have studied these issues enough to note that each engine & carburetor combination is different, plus gearing, weight, cam selection, add to that variables such as elevation, seasonal variations, fuel quality and it quickly becomes apparent that while "what power valve/jetting/timing are you using" is useful for a starting point, it will be just that. The main thing with power valves (economizer) is to be assured that it is NOT opening at steady, low load cruise. As a power circuit it is tuned independent of the others.

A mechanic's vacuum gauge is VERY useful for engine tuning and diagnostics. I don't know how anyone would get along without it. Wideband O2 sensors are worth your time as well.