Dbl Grv Pulley

The MOROSO Double Groove Pulley (Part Number 64210) is a precision crankshaft pulley engineered for Big Block Chevy engines running underdrive configurations with V-belt drive systems. This 5.375-inch diameter aluminum pulley features a natural finish and is specifically designed for short water pump applications, making it an essential component for builds prioritizing reduced accessory load and improved power delivery to the flywheel.

The two-groove design accommodates standard serpentine or multi-belt configurations common in Big Block Chevy engine bays. As an underdrive pulley, it reduces the rotational speed of engine accessories relative to crankshaft RPM—typically by 15–20%—which decreases parasitic drag on the engine. This translates to measurable gains in crank horsepower, particularly noticeable in naturally aspirated applications where every efficiency point matters. The aluminum construction provides a balance between weight reduction and thermal dissipation, while the short water pump compatibility ensures proper fitment in tight engine compartments without requiring additional bracket modifications.

This pulley suits Big Block Chevy owners building high-output street engines, hot rods, or performance vehicles where minimizing accessory parasitic loss is a priority. Whether upgrading from a factory pulley or integrating into a complete underdrive system, this MOROSO component delivers reliable service in demanding engine applications. Weighing 1.89 lbs and compact in footprint (7.45 x 3.25 x 8.75 inches), it installs straightforwardly on compatible Big Block Chevy platforms.