Spark plugs that haven't been changed for a long time can become one with the cylinder head. Fortunately, it's possible to repair damaged threads instead of scrapping the head. (Photograph by Chris ...

The space, or gap, between the center and side electrodes needs to be an exact distance across; otherwise, your plugs don't fire efficiently. Adjusting the distance between the two electrodesis called ...

Spark plugs sit at the center of every gasoline engine’s heartbeat, turning fuel and air into the controlled explosions that move your car. When they work properly, you feel smooth power, quick starts ...