However, once roller cams began moving from the racetrack to the street, increased durability became mandatory. When Chevrolet began using factory-issue roller cams, it used a steel distributor gear to mesh with the steel billet cam. However, the distributor gears are treated with a special coating to limit wear and protect the cam. Ford roller cams also use a treated steel distributor gear. These gears seem to be compatible with aftermarket steel cams as well.
Some aftermarket roller camshafts have alternative means of coping with this issue. Comp Cams has been using ductile-iron roller camshafts for some applications that are treated to an austempering process that leaves the lobes harder than the cam's distributor drive gear, which is not treated. This permits the use of a standard iron distributor gear. Crane Cams takes a different approach by using steel roller cams with pressed-on iron distributor drive gears, again allowing iron distributor gears. Make sure you research the components you intend to use for compatibility before using them together.