Distance from Air Filter Above Carb to Carb Top??

Rumble,
What makes you think 2 1/2" clearance is the minimum? Just wondering, do you have source/data that recommends this?
I do not see a problem in the pic in post #6, with a 1 1/2" gap. I spot a Carter/Edel AFB/AVS. The biggest size is 800 cfm with 1 3/4" t/bores, total area of 9.6 sq in. Using 8" as the smallest diameter of the A/C base where the 1 1/2" restriction occurs, I get 37.7 sq in of breathing area, 4 times the area of the bores so I don't see how a flow restriction could occur. Also, plenty of clearance above the carb vents.