The 1 1/2 turn initial setting is a beginning point to allow the engine to idle on startup after a rebuild. Use the vacuum gauge to fine tune the mixture, unless you're willing to invest a few thousand dollars in a 4-gas exhaust analyzer for a really high tech way to determine the ideal mixture setting.
Jerry
It's quite precise at 2.5 turns -- can't go much on either side before it affects max vacuum. I'll still have to monitor it for potential vac leaks as I have modified the base attachments to the intake manifold: an assembly of gaskets, thick heat spacer and custom 1/8" aluminum plate (heat dissipation/sink).
To that point today I noticed just the tiniest bit of hesitation/stumbling when punching the pedal from 1/2 throttle.
But for the moment it is acceptable considering all that I've been through with this carb.
Maybe think differently as I get used to the feel.
