The space, or gap, between the center and side electrodes needs to be an exact distance across; otherwise, your plugs don't fire efficiently. Adjusting the distance between the two electrodesis called ...

How often you replace spark plugs depends on the type of plugs you have. You may have 30,000-mile plugs, or if the plugs have platinum tips, they may be good for up to 100,000 miles, although some ...