Crankshaft Pulley, 20 Tooth, BBC Moroso Radius Tooth Vacuum Pump Pulleys are designed to work more efficiently and take less power to drive your vacuum pump. Moroso Radius Tooth Vacuum Pump Pulleys are made to use a. 500 wide drive belt and with a wide variety of drive pulley sizes, most drive ratios you may need are achievable. This pulley is made to accept a 1/2 shaft, 3-hole OEM design. Moroso Radius Tooth Drive Pulleys are designed with the latest 8mm tooth technology, and will add to the efficiency of the entire round tooth drive combination. Available in sizes that will not only give you the ratio you want, but will adjust the centerline measurement between your pump and crankshaft center. Moroso Drive Pulleys fit any 1.00 mandrel with a 1/8 keyway slot.