[Barry_R]

Engine off.

Fire is a bad thing - and those little gaskets under the locknut will tear and spray at the worst possible time. Can't put that genie back into the bottle if it gets out and finds something hot. Trust me on that one...

I adjust them a flat of the nut at a time - easy to guage 1/6 of a turn that way. If you are reasonably close you are plenty good enough - this ain't a religious setting. If you are close and you're running out of fuel - check the float drop - not the level. If the float can't drop enough it won't allow the bowls to fill. Usually a non-issue on Holleys but I've seen some very "creative" worksmanship over the years...