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 ...

If you've driven a gas-powered car for long enough, you might've had to deal with spark plug ejection at one point or another ...

The gap between the center and side electrodes needs to be an exact distance across; otherwise, your plugs won't fire efficiently. Remember: Gap new as well as old spark plugs, even if the package ...