The camshaft controls the intake and exhaust valves of an internal combustion engine, regulating the four strokes (Intake, Compression, Power, and Exhaust) of the ignition process. The camshaft is sequenced to rotate at half the speed of the crankshaft, and all camshafts must be properly "timed" or severe engine damage could occur. Installing camshafts is advanced engine work, but you can learn to approach the job as safely as possible for your make and model