OK, well now I'm inclined not to use these rings.

However, I have a related question.

I have an old set of Childs and Albert DuraMoly ZeroGap rings. The second ring (ZeroGap) and the oil ring say 4.375 bore,
but the top ring is labeled 4.380. An old C&A ring catalog has the note:

For file fit rings, the part number de-codes as
PREFIX - THICKNESS x BORE SIZE + .005

I think this means that the C&A top ring, labeled 4.380, is .005 oversize. Intended for file fitting into a 4.375 bore.


Now, the rings I was hoping to use are Sealed Power E-424K-060. However the note in the box does not say anything about file fitting these.
So I put one ring in my new 4.372 bore and it does not go in unless I overlap the ends about 1 or 2 thou, negative ring gap !
Meaning that in a true 4.380 bore, they would have about .023 gap.
File fitting NOT needed for these rings labeled 4.320+.060 ?

Thanks for humoring me, but the devil's in the details !