Has anyone had to re-adjust their idle mixture after installing a spacer? Mine is only a 1/2" (4-hole), and I had to go another 1/2-turn out on the screws (Holley) after putting it on. Is this normal? I wouldn't expect a 1/2" to make that much difference.
vacuuuuuuum if it were creating a vacuum leak the screw would make little or no change.....do you own a vacuum gauge? Try tuning the idle with a vacuum gauge. I just Bought a 4 hole 1/2 inch spacer but havent put it on yet. I have carb to intake sealing issue and can turn the idle mix screw in on one side with no effect.
Yes, I used a vacuum gauge. I was just trying to determine if it was the spacer, or some other reason for requiring the additional half-turn out. Previously, this engine always liked 1 full turn out with this Holley.
interesting Just interested to know which intake are you using? and why did you go for the spacer? I went for the spacer because I am using an F4B and they cast the carb platform small.
For no other reason than heat insulation. Today's gasoline has a lower boiling point than it did years ago. It's only a 1/2" spacer. Performer RPM manifold.
Does this issue coincide with the rpm limitation in your other post? If so you may have debris in the fuel bowls.
