Time was when a valve job was done with some valve-grinding compound and a vacuum cup on a stick. But no more. Today's high performance engines require the same machining precision in the valves that ...

A small gap with big importance in the performance and health of an engine - here's everything you need to know.

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.