Holley Street Dominator vs '73 Cast intake

I'll guess you have something going on with jetting or fuel delivery.
yeah, I didn't do anything but drop the carb on both intakes. Could be that it was, by chance, better tuned for the cast. I know with more runs I could have played with it and somewhere picked up 8 hundredths of a second to match the 14.95 time, but I don't think on this day I was going to get my 2.3 mph back.