Small Block Chevy Cast Alum. Long Pump Double Groove Lower Pulley

Cast Aluminum double groove pulleys for Small Block Chevy feature a 20% reduction. Reduction pulleys have a smaller diameter which slows the speed of your fan, water pump, and alternator to reduce drag for more top-end horsepower. Plus, high RPM water pump operation is improved due to reduced fluid cavitation. This is a 25% reduction pulley when used with the correct upper pulley, part number 91015476. Machined from lightweight cast aluminum Superior belt retention with extra-deep grooves 20% reduction slows accessories down for less drag Adds top-end horsepower Reduces water pump impeller speed below cavitation threshold Improved high-RPM cooling capabilities 910-15488 5-7/16" O.D. Available for long water pumps. 5/8" shaft. Note: The lower crank pulleys are manufactured thicker than normal stock pulleys. This requires longer 3/8" bolts to be purchased separately. Allen head type bolts recommended. Item Details Cast Aluminum Lower