Last month's "How It Works" story gave you the basics of the four-stroke cycle, describing the motion of the intake and exhaust valves in relation to the piston moving up and down in the cylinder.

The crank gear (A) is exactly half the size of the cam gear (B). The cam turns only one revolution for every two revolutions of the crank. This is so the exhaust and intake valves will open and dose ...

Dual Over Head Cam (DOHC) configurations use individual intake and exhaust camshafts. Once the domain of high-performance and luxury cars, DOHC engines are now very common, even in the light truck and ...