IV. Shell and Shield Thread - Cleaning.
Spark plug shell and shield threads should be wire brushed so they are free and clean from old thread lubricating
compounds, anti-seize and foreign deposits.
This operation can be accomplished with the use of a commercially
obtainable Fine Wire Scratch Brush, or a Power-Driven Fine Wire (.005 diameter) Wheel Brush.
NEVER BRUSH ELECTRODES OR INSULATOR PORTIONS
After cleaning, examine thread forms for cleanliness and nicks which can be smoothed out or touched up at this time with
a small three-cornered needle file.
Discard spark plugs with badly nicked, deformed or stripped threads to avoid
damaging the engine cylinder head bushings.
V. Ceramic Shielding Barrel - Cleaning
The cleaning of spark plug ceramic shielding barrel inner surfaces is an important operation which requires careful
handling with appropriate type equipment for removing oily films and other deposits that could become conductive
seepage paths for applied ignition voltages. To accomplish this operation on high altitude 3/4" diameter, or low altitude,
5/8" diameter, shielding barrels, chuck an AV17-1 Sleeve Cleaning Tool Assembly into a drill press chuck, or attach to
the protruding shaft of a small electric motor. Recommended operating speeds are around 1000 to 1725 RPM.
1. Apply a small quantity of water soluable AV7-1 Sleeve Cleaning Compound into the spark plug shielding barrel