Pardon the copy + paste, just a little more info..
Matching camshaft and distributor gears is one of the most critical,yet often overlooked step in engine assembly. The proper distributorgear for your camshaft differs by both the material and the kind oflifter for which your camshaft was designed. Using the wrong materialcan lead to premature gear wear, possible camshaft wear and ultimatelyengine failure.
First off, no steel distributor gear is compatible with both flattappet and hydraulic roller cams. This is because hydraulic rollers canbe made from two possible materials and either of those materialsrequires a different gear than the flat tappet cam. Regardless, a steelgear is not compatible with a cast iron flat tappet cam.
Distributor Gear Materials:
1.Cast Iron
2.Composite(offers great life, conforms well to the mating cam gear, and is compatible with ANY camshaft gear material)
3.Melonized or hardened steel(material that OEMs use with factory roller cams; many aftermarketdistributor manufacturers use these as the default gears for theirdistributors)
4.Bronze(conforms well to the matingcamshaft gear and will not damage the camshaft gear, but it is a selfsacrificing gear intended to be used in race applications only andshould be replaced about once a year)
If you have a cast iron hydraulic or solid flat tappet cam, your distributor gear options are:
1.Cast iron distributor gear
2.Composite distributor gear
If you have an austempered ductile iron hydraulic or solid roller cam, your two options are:
1.Melonized or hardened steel distributor gear
2.Composite distributor gear
If you have a billet steel hydraulic or solid roller cam, your two options are:
1.Bronze distributor gear
2.Composite distributor gear
COMPCams recommends the composite gear because it is compatible with allcamshaft gears – flat tappet, austempered cast iron cores, and billetcores. If the steel gear is not hardened, it is not compatible witheither of the roller cam types.
Note:If you have anaustempered core hydraulic roller cam and a .500? shaft distributorwith a steel gear, verify with the manufacturer of the distributor thatthe steel gear they use is a melonized or hardened steel material andit will work fine.