A spark plug thread chaser isn't always the answer, but it can make a big difference when you're installing fresh new plugs.

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 ...

Add Yahoo as a preferred source to see more of our stories on Google. But spark plugs live in harsh environments. Not only do they see massive changes in temperature, but schmutz tends to accumulate ...