|This tools expands the spark gap of any massive electrode aviation plug safely and efficently -- with the key word being safely... In the past when you over-gapped a plug, and wanted to expand it back out, you would resort to using a screwdriver, dental pick, or whatever else was on hand. But this was almost a sure way to do damage to the plug. Because you would invariably push the screwdriver between the electrodes, which would cause pressure to the center electrode and risk cracking its ceramic casing. The end result would be either reduced performance or total spark plug failure. Not so with this tool.|
When youve overadjusted the gap and need to expand it back, this is way better than trying to pull it back with pliers. Just be careful where and how you use the tool to apply leverage.
For those of us who sometimes over adjust the gap on a spark plug or need to make a small expansion adjustment - this tool does the job. As a mode of caution - care must be taken when using this tool as it will leave a notch on the rim of the plug. A small fine jewelers file will clean up about 90% of the notch but, when using this tool, small correction is the key with light pressure. Also, make sure that the finished surface of the tool is placed as square as possible against the rim of the plug. This will reduce any chance of putting a notch on the rim of the plug.
The documents indicate it will work on all massive electrode plugs, but no mention of the BY series twin electrode projected core nose units.