A camshaft is a long bar with egg-shaped eccentric lobes, one lobe for each valve and fuel injector (discussed later). As the camshaft is rotated, the follower is forced up and down as it follows the profile of the cam lobe.

The camshaft gears increase torque and horsepower without having to change the camshaft(s) and are mandatory for engines that are milled, forced induction, high compression, and/or utilizing aftermarket competition cams.

Basically, cam gears are for heavily modified engines. If the engine timing of the cam is off, your car will either be running rough or not at all. If the ignition timing is the problem, it isn't as easy to notice as it has four cycles.