Let's say you've just removed an old spark plug. Does it have any life left in it? Can it be reused if it is cleaned properly? Let's take a closer look.

Hand-thread the spark plug back into the engine, being very careful not to cross the threads. Then tighten the spark plug, but don’t over-tighten it or it’ll crack.

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 ...

Just like cars, lawn mower engines need their spark plugs changed on a regular basis. How often should you swap the old ones out for new ones?