MSD designed this 85813 Distributor Gear for 1968-1997 Big Block and FE Ford engines with hydrualic roller camshaft. This gear is machined from a proprietary formulated steel, and is micro polished for smooth contact. It also features an increased outer hardened layer thickness (RC 55-60), and Melonite QPQ coated to reduce friction and initial wear. MSD researched and tested a variety of metallurgical compositions, heat treating and coatings to provide a strong, durable distributor gear. This means long life, an easy break-in period and reliable performance! MSD 85813 Distributor Gear Features: For Ford Big Block and FE engines from 1968-1997 with Hydraulic Roller Camshaft Distributor Gear Material: Steel Distributor Shaft Diameter: 0.531 in. Distributor Gear Rotation: Standard Roll Pin Included: Yes Drilling Required: No Quantity: Sold individually From street cruisers to Top Fuel dragsters, MSD's ignition systems have been the industry leader for over 40 years. MSD continues to push the envelope with cutting-edge ignition technology as well as intake manifolds and EFI systems.