V-Belt Crankshaft Pulley 5in Dia

The V-Belt Crankshaft Pulley 5in Dia (MOR23525) from Moroso is purpose-built for engine builders and hot rodders who demand precision accessory drive systems. Whether you're upgrading a classic muscle car, constructing a high-performance street engine, or fine-tuning a weekend racer, this single-groove aluminum pulley serves as the heart of your belt-driven accessory package. It's engineered for applications where stock pulleys fall short—delivering reliable crankshaft engagement without the weight penalty or dimensional compromises of cast-iron alternatives.

Machined from lightweight aluminum and finished in durable black anodize, this 5-inch diameter pulley features a single V-belt groove paired with a 1-inch mandrel bore and 1/8-inch keyway for secure crankshaft mounting. The compact 5-inch diameter optimizes belt speed ratios, enabling you to select proportional pulley sizes for your water pump, alternator, and power steering pump without sacrificing efficiency or creating slip issues. Black anodizing provides corrosion resistance and a clean aesthetic while reducing thermal absorption, critical in high-output engines where underhood temperatures spike significantly.

Professionals and dedicated enthusiasts rely on this pulley when building tight, efficient accessory drive systems for small-block and mid-size engines where space and weight matter. Its lightweight construction (1.12 lbs) minimizes parasitic drag on the crankshaft, freeing horsepower for the wheels rather than spinning heavy cast alternators or water pump impellers. Installation is straightforward—the standard 1-inch bore and keyway mate directly to existing crankshaft hardware, making it an ideal upgrade component for engine swaps, restorations, and performance rebuilds across domestic and import platforms.