[Formulajones]

Yep, too lean will have a horrible smell and burn your eye's too.

I prefer to adjust the idle mixture for the "strongest" idle, which is usually a pinch on the fat side in most cases. The stronger idle just works better in day to day driving with no monkeying around with the throttle on a luke warm start and just better all around in gear idling in all conditions.

How rich that needs to be just depends on the engine setup and camshaft. I find that an engine with a working heat cross over can get away with a leaner idle mixture without exhibiting wonky idle problems, while no heat cross over, or a restricted cross over tends to need a little more idle fuel to be happy. Either way with todays gas I prefer them to be a little richer rather than leaner anyway.