Iconic 427 runs very rich since new?

[cbreez]

Originally Posted by RT3_1350

All 4 carb needles on the Holley 670 are set at 3/4 turn out.
Do have an oil leak at the front of the pan where the motor builder put gobs of black silicon where the oil pan curves around the crank.

Proper idle mixture adjustment is done with a vacuum gauge, period...the quick and dirty way is to make the screws equal.
Black silicone is SOP and used every day on the front of most oil pans.

That Holley out of the box should need minimal adjustment. Most black overly rich plugs are from jetting problems, not idle mixture problems. Most "misses" aren't carb related but ignition related...retarded timing causes run on...