I have a Holley 80508-S box stock except that I have added the quick change spring kit and just got the metering block kit.

The carb came with 72 primaries and 21 secondaries. Holley did an excellent job as it runs pretty sweet right out of the box. Although, it's a gas hog (10's) and I sense that it's a little rich.

When I dig into it, my plan was to drop the primaries to 70's and as for the secondaries, I need some help. The new M/B came with 76's and I remember reading a post some time ago that a good point to start is 80's.

It would be rather naive to think that I could make one change and have it be right the first time, but I would like to be somewhere close. This is my first go around at carb tuning for performance. I've rebuilt carbs before but only to book specs.

Anyone have any suggestions?

 

My suggestion is run it and see. 76's shouldn't be that far off. Get an A/F gauge so you can keep track of how it's doing.