For those of you running IMCA and SK Modifieds with an HEI-equipped SB-Chevy, here’s your air cleaner. The 1 1/2'' forward offset is designed to allow HEI distributor clearance. The drop-base model works with 2-bbl Holley carbs only and features a 1 3/4'' drop for a stacking height of 2 3/4'' above the carb neck. The raised base unit fits most all 2 and 4-bbl Holley carbs and features a 3/8'' raised bottom for a stacking height of 4 3/4