Oddball size piston rings needed

[Marshall V. Daut]

I am working on a friend's Model "B" engine that was rebuilt some time ago (except for the bearings) and I have come across a new one on me. His aluminum pistons are clearly marked "120", not "100" or even "125". This, of course, means the cylinders are bored .120" oversized. I don't see in catalogs that this size is available. The pistons and cylinder wear are good, so we'd just like to replace the rings rather than boring out to the next size at .125" and buying new pistons.
Does anyone know where .120" piston rings are available?
Thanks in advance.
Marshall

[Wick]

Check with schwams or some of the supply houses...you will find them.

[ford3]

buy the .125 rings and file or grind the ends down to fit the .120 pistons, allow .004 clearance for ring gap for every inch of cylinder bore, this is one way to get around your problem if you cant find the rings you need, or call Egge and see if they have the rings

[ckulchar]

I've bought rings from this fellow before.

http://www.ringspacers.com/

Charley Kulchar
Amherst Ohio

[Patrick L.]

If you can't find the proper size rings, I too would use the .125s and just make sure to file the proper end gap.

[ursus]

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I have a set of Continental brand rings sized 0.110 - 0.120 oversize. How's that for odd? I had planned to cut down a set of "semi" sized pistons to match for 0.115 oversize cylinders but could not find anybody with a piston lathe. Old time machine shops are like some lost civilisation.

[MikeK]

If you use .125 rings re-gapped for a .120 bore, the increase in ring pressure to the walls will be less than 2%. Rings between different manufacturers vary as much as 20% in tension, and it is not uncommon to see 5% variance in a new boxed set. The 2% from regapping the .125 rings for .120 becomes a moot point of concern.

[Patrick L.]

I'm surprised that our resident professional engine guys haven't given an opinion.

[d.j. moordigian]

Originally Posted by MikeK

If you use .125 rings re-gapped for a .120 bore, the increase in ring pressure to the walls will be less than 2%. Rings between different manufacturers vary as much as 20% in tension, and it is not uncommon to see 5% variance in a new boxed set. The 2% from regapping the .125 rings for .120 becomes a moot point of concern.

I also agree with Mike. I usually buy "5 over" ring sets for the engines
I do. There is no question on ring gap when done. I also use a ring
filler, made for the job and not a file.

Dudley

[George Miller]

I would also use .125 over and file the ends. Back in the day they use to sell odd size rings. They also had rings that they said would cover a difference of .020. I never used any of them. You could by semi pistons and have them turned to the size you wanted. You could also by semi bearings and have them bored to the size you wanted.

[Marshall V. Daut]

Thanks to everyone, who replied with suggestions. I dropped the engine off yesterday at Antique Engine Rebuilding (A.E.R.) in Skokie, Illinois, for insert bearing work. Owner Rich Falluca advised the same thing as you guys - file the end gaps of .125" piston rings to adapt them to the .120 pistons in this engine. His words are gospel for me, so that's what I'll do. I just needed his verification on this matter before proceeding with all of your advice.
I'm still rather incredulous, however, that no correctly-sized rings seem to be available for these pistons.
Marshall

[wrndln]

Marshall, where have you been? It seems this is the first post I have seen by you for a long, long time. I though maybe you have given up on model A's. BTW, I have used Timesaver on two engines now, but haven't run them enough to really tell if it made a difference. It sure seems like it should.
Rusty Nelson

[BRENT in 10-uh-C]

Originally Posted by wrndln

Marshall, where have you been? It seems this is the first post I have seen by you for a long, long time. I though maybe you have given up on model A's. BTW, I have used Timesaver on two engines now, but haven't run them enough to really tell if it made a difference. It sure seems like it should.
Rusty Nelson

Yeah Marshall, where have you been??

Ironically, I delivered a car to Iowa City last Thursday and on the way home as I crossed the river looking at all the flooding, your name popped into my mind and I wondered if you were still there in the "Big D". I then wondered why anyone would leave the AZ weather to move back to 10' of snowfall a year!! In all seriousness, I hope you are doing well.

[Tinbasher]

Try "Egge.com" in California. They will make up what ever you need. Pistons, rings, Etc. They made a set for the "Barrie Bell" (Lycoming motor)

The Old Tinbasher