As you have found out, NOS piston rings are becoming scarce. These motors were made from 1952-1967 in various forms, and there are thousands and thousands of them still out there. Maybe find a parts motor with good pistons/rings and scavenge the entire piston and connecting rod assemblies from it. The connecting rod caps must stay with the connecting rod that they came with, and in the exact orientation, as they are bored together at the factory making each set unique.

There may be rings listed by other parts numbers from the 1940’s OMC motors that fit, but that will require more looking into.

John Miller wrote:

I became the proud owner of a 3hp
Evinrude 1955 year. The block was stuck but after a little work it is free. The rings are broken, I went out to find a set of rings for this motor (they are not readily available). The ones I have found are $300.00 per piston. Does anybody know of a set (2) rings that will fit this engine; maybe same size and diameter from another model engine? Please know I am trying to put together a piece of history and keep it from going to the trash.

Thank you in advance for any information, it will be greatly appreciated.

John

There are a few members here that have many new old stock items, they might be able to help you for a more reasonble cost.  I saw the ebay auction for $120, I guess they must think those rings are made of gold!