I am making some threaded inserts-(helical) inserts.
They are made out of steel and have a seating flange, to repair stripped threads.
I have an old 14mm thread chaser but needed a tap to cut new threads.
I bought an Irwin 14mm x 1.25mm plug tap and have discovered it is .013 larger in diameter then a spark plug.
Thread chaser is exactly same diameter as spark plug.
Needless to say, the spark plug has a small amount of slop which would probably be ok since inserts are steel, but would be questionable with an aluminum head.
If a spark plug has a special 14 x 1.25mm, I was not aware.
They are made out of steel and have a seating flange, to repair stripped threads.
I have an old 14mm thread chaser but needed a tap to cut new threads.
I bought an Irwin 14mm x 1.25mm plug tap and have discovered it is .013 larger in diameter then a spark plug.
Thread chaser is exactly same diameter as spark plug.
Needless to say, the spark plug has a small amount of slop which would probably be ok since inserts are steel, but would be questionable with an aluminum head.
If a spark plug has a special 14 x 1.25mm, I was not aware.