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 ...

A cylinder head, especially an aluminum one, seldom fails on its own. Typically, there's another matter to contend with. Undoubtedly, the most frequent cause of cylinder-head cracking is an overheated ...

For hot rodders, spark plugs are often nothing more than inspection tools that reveal whether an engine is running too rich, too lean, or just right. Street guys look for a nice tannish-brown tint on ...