SU Carburetor Specifications SU Bore Size Measure the diameter of the SU bore at the point where it bolts up to the intake manifold.HIF4 – 1.5″HS6 – 1.75″ Updated on 02/05/2021 Was this article helpful? Yes No Related Articles SU Carburetor Rebuild SU Carburetor Identification SU Carburetor Exploded View SU Carburetor Adjustments Need Support?Can't find the answer you're looking for?Contact Support