1973 Holley 1920 Accelerator Pump Question - Stumble Off Idle
Innermost hole = SMALLEST pump shot. Outermost hole = largest pump shot. Try moving the link one hole outward (middle hole) and see how it does.
Beyond that: Carburetor operation and repair manuals and links to training movies and carb repair/modification threads (heavy on Holley 1920 material) are posted
here, and other tune-up parts and technique suggestions in
this post.