4. From this view you can see how much wider the roller cam’s lobe is than the flat tappet. Also note the distributor gear. Because our roller is a cast cam, its distributor drive gear will be compatible with the cast gear on our distributor. If this were a billet roller cam, we’d either have to install a bronze distributor gear, or one of the new coated gears that works with both cast and billet camshafts.