"a plume of smoke is an ideal indication of correct carb set"

Not to be critical, but IMO that plume of smoke means very little. If there is very little smoke, you are running so lean that you might toast your engine, but you really have to go on sound, temperature (is the backplate so hot it sizzles spit?-bad), and how much power it has. It can still be lean and spitting alot of smoke because heli fuel has so much lubrication in it.

I've noticed that weather has a much greater impact on heli tuning than fixed wing, so I'm tuning much more that I ever thought I'd need to.