This Mazda Competition Parts Single Sheave Alternator Pulley reduces alternator RPM approximately 20% from stock for street high-performance and racing use. For use on virtually all 1974-8-91 12A and 13B rotary engines, this aluminum underdrive pulley (3.2 oz) is intended for use with the Single Sheave Main Drive Pulley, although it can be used with the stock main drive pulley. The pulley is bored 15mm for use on small shaft alternators, although it can be bored larger if necessary.

Precision-machined from billet aluminum alloy, each pulley is finished with a hard anodized surface treatment to ensure superior longevity and excellent abrasion resistance. As compared with standard anodizing processes (typically identified by components finished with a bright red or blue finish), a hard-anodized aluminum component will offer comparatively superior durability and wear characteristics. Hard anodized components are typically identified by a darker surface coating, most commonly with a dark grey or black matte finish appearance.

Installation Note: It is not practical to offer a standard replacement belt due to the variations in engine configurations. After measuring the distance required for your application, we suggest you contact your local auto parts store to obtain the required 3/8-inch wide replacement belt.