Carb Tuning with AFR Guage

Walker434 said

Hey guys I need some help. At wide open throttle the car is too rich at lower and mid RPM ranges. Like 10.5:1. By the time I hit 6,000 RPM its much better at like 12.0:1.

This is a 360 with a procharger and Holley HP 750 converted to blow through. Running 10 lbs of boost.

What would I need to change to make it go more lean at lower and mid RPMs but not change the high rpm AFRs?

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In my admittedly limited understanding of altering fuel curves, the way they are altered is by changing the air bleeds that feed the boosters. That is assuming you have the adjustable/removable ones. The ones that alter the slope of the fuel curve of the main jet & power valve flow are the larger diameter air bleeds at the top of the carb.

From everything I have read while trying to adjust carbs using an A/F gauge, altering these air bleeds changes the slope of the fuel curve for situations such as you are describing.

Obviously, documenting all your changes is a must, and if you have none adjustable ones in your carb, you can only drill them to a larger size unless you drill & tap your carb to fit adjustable ones.