Question about high speed air bleed on Holley 1945



This is (I believe) the high speed air bleed. It has 3 little holes about halfway up. Interestingly, it has a hole at the bottom but it has been plugged by a a small amount of solder. Does anyone know what the benefit is to that either remaining plugged or not plugged? I know it's an odd question but it seems like it was originally designed with a hole and then was plugged later.
Thanks