I try and use a 1/2 minimum or more if possible according to the type of manifold, rpm range and of course space available.........I run a 1/2" 4 hole under my Dommy..............

72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....