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 ...

Along with swapping out the air filter and changing the oil, replacing the spark plugs is one of the few things left that require service on a modern gasoline engine. Some newer than the twenty-year ...

While working with our 4.6 GT open-track project car, we came across one of those "gotcha" situations begging for a bit of explanation. Admittedly, it's a simple matter of using the correct spark plug ...

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 ...