Farmall M MW Pistons

Blight · Jan 3, 2018

I have a Farmall M that has M&W pistons. The piston has AP 75 on them. I was wondering if anybody know a set of rings part number I need. Thanks

Janicholson · Jan 3, 2018

Three things need to be discovered. (there were/are likely several different M&W pistons)
What is the number of rings on the piston? What is the width, top to bottom, of the existing ring set (all rings)? and what is the bore measurement/piston fit as measured by a bore gauge, not calipers. The new rings can certainly be found, but creating the full set might require doing research from suppliers. Ring groove wear is also an issue and can be repaired using machining methods to rebuild the walls with steel spacers. Jim

D Slater · Jan 3, 2018

Think that's a 4.125 piston, if it is a M block they are running without sleeves or block is bored to SM, 400 and 450 size or you have a later block. Don't know if anything is special about the rings but I think those used three 3/32 wide and a 1/4 wide. Going by memory I think IH used that size rings on some of the 4.125 pistons. Could make sure and let you know if nothing else shows up and you want to try.

David G · Jan 3, 2018

In my observations, most of the ring groove wear occurred in the top ring, it is pretty easy to square them up with a lathe and put in a spacer.

Important note when using spacers, count them BEFORE you start, have seen spares and easy to miscount.

Duner Wi · Jan 4, 2018

Hastings lists 3 different ring sets for M&W pistons depending on ring width.
Look at 2C7580,2C7794 and 2C7553.

Farmall M MW Pistons

Blight

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Janicholson

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D Slater

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David G

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Duner Wi

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