My recent search turned up the opinion by several that the "tried and true" 1 1/2 turns out should actually be "3 turns out" with modern fuel. I don't have enough experience to comment, but food for thought.
My Auto Restorer showed up today. In an article by Milt Webb
MiltTheInstructor.com, he is tuning up a 27 Hupmobile. He discusses opening the idle mixture screw until the engine stumbles (
over-rich), then closing the screw in until it runs smoothly again, then in further until the RPMs drop off (
lean point). Final adjustment is half way between these two points (generally). This assumes everything else is tuned, ie: timing, advance, plug gap, point gap, etc. and should be done on a warmed up engine.
Sounds stupid, I know, but I never really thought of this.
Makes sense.
-Michael
