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Old 03-01-2017, 11:24 PM   #1
Fourdy
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Default Threw a penny in the wishing well - - -

and hoping I might find someone that may have the bottom ring of a Speedway 4 ring, 3 5/16" piston willing to trade for $'s. Yes, I broke it while installing. lol

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Old 03-01-2017, 11:37 PM   #2
tubman
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Default Re: Threw a penny in the wishing well - - -

I have a set of those. After much research and checking with those who know, I decided just to leave the bottom ring set off. I suggest you do this as well (unless you have already had the engine balanced). If you want them, just let me know and you can have them for the cost of shipping. One problem; I am in Florida until May and the rings are in Minnesota. I may be able to talk my neighbor to go to my shop and dig through things, but I can't guarantee it.
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Old 03-02-2017, 01:38 AM   #3
Fourdy
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Default Re: Threw a penny in the wishing well - - -

Tubman,

PM'd you

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Old 03-02-2017, 01:23 PM   #4
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Default Re: Threw a penny in the wishing well - - -

Back many years ago I was installing rings in my Model A. The ring set I found were for 3 ring pistons and my pistons were 4 ring pistons. The parts store ordered me 4 more rings from Grant. It wasn't very expensive to do that but I am talking about back early 1960's. If I remember right I needed an extra compression ring.
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Old 03-02-2017, 01:40 PM   #5
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Default Re: Threw a penny in the wishing well - - -

On our flatheads (at least), the bottom ring is another oil ring. It was added as a stopgap to reduce oil consumption in the early engines. With today's ring technology, it is totally unnecessary and only adds more drag to the cylinder and other complications. Take a look at a modern piston/ring assembly some time.

Now, if your using 70 year old NOS rings, you may want to run the fourth ring, but why would anyone want to do that? Marvin is correct that rings are a stock item and it shouldn't be too difficult or expensive to obtain what the OP needs.
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Old 03-02-2017, 02:20 PM   #6
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Is there a difference in the skirt length between the 3 and 4 ring piston? My inexperience wonders if there would be piston rock without the bottom ring.

Foudry
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Old 03-02-2017, 02:50 PM   #7
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Default Re: Threw a penny in the wishing well - - -

Fourdy, I run the speedway 3-5/16" pistons. I left the lower rings off because the French block has a little notch which was exposing the rings. It runs fine with just the top 3. Leave them out and you'll have 7 spares.

The ring does not add any support to the piston.

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Old 03-02-2017, 02:52 PM   #8
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Default Re: Threw a penny in the wishing well - - -

Like I say; take a look at a modern piston/ring assembly (that probably runs at a lot higher speed) and make your own decision. (I've seen 'em a lot shorter than this, but this is the only image I could find in a hurry.)
Attached Images
File Type: jpg piston.jpg (1.7 KB, 251 views)
File Type: jpg FHpiston.jpg (2.0 KB, 244 views)

Last edited by tubman; 03-02-2017 at 03:15 PM.
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Old 03-02-2017, 04:54 PM   #9
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Default Re: Threw a penny in the wishing well - - -

Quote:
Originally Posted by Fourdy View Post
Is there a difference in the skirt length between the 3 and 4 ring piston? My inexperience wonders if there would be piston rock without the bottom ring.

Foudry
The rings are free to move around in the piston grooves, so don't think your going to get much support from them. Haven't measure it, but I would bet that the piston to wall clearance is less than the inside edge of the ring to piston clearance.
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Old 03-02-2017, 10:19 PM   #10
Fourdy
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Default Re: Threw a penny in the wishing well - - -

Thanks to all of you for your experienced advice. I will join the club of "no bottom ring". Thank you Tubman for your generous offer. Oh - - - If anyone needs a bottom ring I now have a few. Big LOL.

Another question. What is the source for pistons that use metric rings I have read so much about. TIA

That was sure worth the penny. lol

Last edited by Fourdy; 03-02-2017 at 10:21 PM. Reason: added verbage
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Old 03-03-2017, 01:14 AM   #11
Kahuna
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Default Re: Threw a penny in the wishing well - - -

Ross pistons and maybe Egge now
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Old 03-03-2017, 09:07 AM   #12
tubman
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Default Re: Threw a penny in the wishing well - - -

I hope you haven't balanced that engine yet!
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Old 03-03-2017, 12:30 PM   #13
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Default Re: Threw a penny in the wishing well - - -

Tubman - no not yet. Engine work starts in a couple months.

Thnx - Fourdy
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Old 03-03-2017, 12:51 PM   #14
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Default Re: Threw a penny in the wishing well - - -

Quote:
Originally Posted by JSeery View Post
The rings are free to move around in the piston grooves, so don't think your going to get much support from them. Haven't measure it, but I would bet that the piston to wall clearance is less than the inside edge of the ring to piston clearance.
It would have to be, or the ring wouldn't be able to do it's job!
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