Pulley Crankshaft V-Belt 4in 1.125in ID

The Jones Racing Products Pulley Crankshaft V-Belt 4in 1.125in ID is a precision-engineered crankshaft pulley designed for high-performance marine and automotive applications. This 4-inch diameter pulley features a 1-1/8 inch mandrel bore with 1/8 inch keyway, offering direct OEM-style compatibility with single-groove V-belt drive systems. Constructed from lightweight aluminum with black anodized finish, it delivers the durability needed in harsh saltwater and freshwater environments while resisting corrosion from continuous exposure.

The black anodized aluminum construction provides corrosion resistance critical for marine engines operating in salt spray conditions. The 4-inch diameter paired with the 1.125-inch mandrel ensures proper belt tension and power transfer efficiency for crankshaft-driven accessories including alternators, water pumps, and superchargers. The precision 1/8-inch keyway maintains secure coupling without slippage under load. Weighing just 0.56 lbs, this pulley contributes minimal rotating mass while supporting reliable performance in demanding high-RPM conditions typical of performance boat engines and high-output automotive platforms.

This crankshaft pulley serves both recreational boaters and serious performance enthusiasts who demand OEM-equivalent reliability. Weekend anglers running outboard and inboard engines benefit from the straightforward universal fitment and corrosion-resistant design. Performance-focused builders—whether upgrading offshore tournament boats or street-to-strip vehicles—rely on Jones Racing Products pulleys for their precision manufacturing and consistent dimensions. The black anodized finish blends seamlessly into modern engine bay aesthetics while providing genuine surface protection against oxidation and salt air degradation.

Jones Racing Products has established credibility in the performance racing and marine aftermarket for delivering machined components that meet strict tolerance standards. This pulley represents the brand's commitment to dimensional accuracy and material quality. Whether replacing a corroded factory pulley or upgrading a restored engine, buyers can expect straightforward installation and years of reliable belt drive operation. The universal design accommodates various belt widths and configurations common across marine and automotive platforms, making this a practical choice for mixed-engine fleets and custom builds.