The following procedures apply to spark plugs for small engine equipment, automotive and other applications using internal combustion engines.
1) Visually inspect the spark plug for any damage or excessive wear.
2) Remove carbon or other deposits with a stiff wire brush.
3) Measure the plug gap with a wire-type or slim type feeler gauge. If necessary, adjust the gap to plug manufacture specifications by bending the side electrode.
4) Make sure the sealing washer is in good condition; place the plug if damaged.
5) Install the plug finger tight to seat the washer correctly, then tighten with a spark plug wrench to compress the sealing washer.
NOTE: Tighten additional 1/2 turn if installing a new spark plug.
Tighten additional 1/8 to 1/4 turn if you are reusing the spark plug.
Take Caution!
Spark plugs must be securely tightened. An improperly tightened plug can become very hot and possibly damage the engine.
Never use a spark plug with an improper heat range rating.