So how does the mixture screw affect things? Usually the best idle mixture appears around 1 1/2 to 2 turns out from all the way in. Turning it in will at some point cause it to start to falter and then turning it out 1/2 a turn or so causes it to even out. One thing that will make the idle unstable is a worn throttle bushing. If you can wiggle the throttle plate so that the shaft moves around in the bore, then it is loose.

Last edited by truckernix; 03/23/2011 12:37 AM.
1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!