Carb tuning, larger accelerator pump nozzle?

Mattax said
Most of the good older Holleys had two holes per channel, each around .026 to .028"
If you're doing three, then they need to be smaller.

Why more holes or larger holes can created unstable flow and what higher and lower positions influence is pretty well covered here.
Emulsion Tuning
A couple posts down is graph showing the effects.

Some more tips on drilling in this thread and ones linked within it
How Are You Drilling Your Set Screws?

Novadude has nice pics in his post.