I'm having the opposite problem. I went from an eddy carb back to a Carter carb. The base that fit over the eddy carb is too big for the Carter 4bbl. The diameters of the carter are 4 1/2" od and 4 1/8" id. The base for the eddy carb is 5 1/8" od. The original 273 air cleaner cover fits over that with no problem.