Holley Carb Fuel Mixture Screws

[John Lokay]

Would someone tell me how sensitive the fuel mixture screws are on a Holley, model 4150, carburetor? For example, when using a vacuum gauge to adjust the air/fuel mixture, would a quarter turn of the screws (either in or out) have much of an impact on the vacuum gauge reading or do you have to turn the screws by more of a 180 degree, 270 degree or 360 degree turn to impact the reading on the vacuum gauge. Thanks

[Joe L.]

Re: Holley Carb Fuel Mixture Screws

John----

The effect on the vacuum gauge reading produced by various amounts of turning the idle mixture screws will vary depending upon where you're at within the range of adjustment-----at some points of adjustment a quarter turn of the screws will have little effect and at other points it will have a large effect.