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There are three major contributors to an engine running rich. These are, in order of the normal procedure in addressing:
(1) defective compression
(2) defective ignition
(3) defective carburetion
A major study was once done of vehicles diagnosed with "carburetor problems" by professional mechanics. The sample consisted of 1000 vehicles. The results:
(1) defective compression (2 percent)
(2) defective ignition (93 percent)
(3) 5 percent actually had carburetor problems.
If you are going to attempt the adjustment of the carburetor, Jerry's post above is worth rereading. The idle mixture control screw adjusts the mixture ONLY at idle. On the typical Rochester B, this setting should be from 1 turn to 1 3/4 turns from lightly seated.
Jon.
Last edited by carbking; 09/24/2008 9:36 PM.
