Racing Beat's Single Sheave Main Pulley for virtually all 1974-91 12A and 13B engines reduces the water pump/alternator drive ratio substantially to avoid water pump cavitation and alternator damage due to the extreme RPMs encountered in racing. This aluminum pulley (6.4 oz) also reduces the engine's rotating inertia and the power loss to the accessories. The pulley is provided with a series of engraved timing marks at 0 degrees (TDC), 12.5 degrees BTC, and 25 degrees BTC.

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.

We do not recommend this underdrive pulley be installed on "street-driven" cars that are used for stop-and-go driving. In addition, we do not recommend the use of this pulley on 1987-91 Turbo II engines unless modifications have been made (shorter intake runners, etc..) to increase the engine's RPM range substantially. Turbo II engines produce their peak power in a lower RPM range, relative to a non-turbo engine.