Different piston ring problem

Hello all, I will get back to my project thread as soon as I can sort this little problem out and finish building the top-end. I hope someone can help - I've searched the web and literature and reckon the quickest route to a solution is to give in and just ask!

I have set of JP (Ozzy) piston rings and below is a photo of the oil control rings:



I have only ever seen three components when rebuilding other engines - 1,2 and 3 from left to right. The fourth gizmo seems designed to fit under the other three to act as a spring. I have fitted these rings to one piston, but they seem to require a lot of finger pressure to compress them. I am wary of causing damage if I just press ahead like a bull in the proverbial.

My relative lack of experience means that I need someone to tell me that this is the right way to go - I certainly can't see any other!

Also - I've read it somewhere and made a note, but now I can't find it - could someone remind me of the best places to position the ring gaps. It seems fairly logical, but a bit of advice can only help.

Thanks in anticipation of your help - I really want to get the barrels on tonight.

Bob

Sounds similar to one of the 2 issues my mate had with his JP piston for his Matchless. Rings way too stiff (couldn't expand them without cutting into the fleash on fingers) and the piston was not fully machined too boot. It siezed within 20 ft of the drive, only sorted by machining the clearance on the ring area and fitting non JP rings. They also use the one blank to cover several models so can be heavier than stock. I would never touch them but as you have them I would at least fit proper rings.

The first ones look like components of a 3-piece ring, but that fourth one looks mighty small in comparison, and not sure where it figures into the equation. No wonder it fits so tight. Like kommando says, if they don't fit, get ones that do.....

I fitted jp oiston and rings a couple of years ago, and definetly do not remember that fourth oil control ring.

Are you sure it wasnt part of the packing to keep from getting damaged.I would be making a call to Ozzyland before I spark up that motor.

Piston rings

Hi just thought I'd give my two cents. I see 3 rings in your picture I am not sure what that 4 item is. I see two comp rings and 1 oil ring that other part certainly does not look like a ring. Is it may be something to assist installing or removing the rings just a guess. Piston rings should be checked for two important clearances and do this check before you install them. Slide the ring inside the cylinder, you need to check that your ring has the proper clearance as it works inside the cylinder. I believe the norm is to check in 3 places. At the top, middle and lower working area of your cylinder barell. The rings need to have this gap to operate for expansion. Now I'm not sure off the top of my head but I believe it to be only a few thou this you will have to check. Sometimes even with the correct size ring you need to file the {gap} slightly to obtain correct clearance. The other check is to determine if you have the correct clearance between the piston groove and ring. You need the correct clearance here as well. You dont want it to be too slopy and you don't want it to be too tight. So with the ring off place the edge into the piston groove and check the clearance again you will have to check for the correct numbers but again I believe it to be only a few thou. I don't really know the condition of your pistons or cylinder barells so this is the short version. Hope it helps you some what. Doxford

PS Ring gap location

Sorry missed your question about location of the ring gap. You want to turn them away from each other so they don't line up together or oil will pass by. Place 1 facing forward another facing to the rear and so on.. Doxford

Re: Piston rings

DOXFORD said:

I see 3 rings in your picture I am not sure what that 4 item is. I see two comp rings and 1 oil ring

Click to expand...

I only see what appears to be a three piece oil control ring and the extra part?

DOXFORD said:

that other part certainly does not look like a ring. Is it may be something to assist installing or removing the rings just a guess.

Click to expand...

I had the same thought, but it doesn't look as if it could do much? I'd guess it is some kind of extra expander spring?

I would strongly suggest that BobV contacts his piston supplier to find out exactly what that part is for.

it is a 4 piece oil control ring! the 2 thin rings are the scrapers the middle is a spacer to keep the scrapers apart and the 4th on the right is the expander to keep it on the cylinder wall. it is an older type of ring and should have no effect on a piston seizing. improper piston clearance or not enough cam in the piston will cause it to seize. it will have more ring tension than newer low tension styles of oil rings and possibly be a little harder on the cylinder wall.
I would assemble it with the first 3 parts spaced 120 deg apart and make sure that no one part has its end gap over the bottom expander's end gap.

They are old tech,most ring supplers stopped using them in the late 80's.The spring expander goes in first,the wavey rail next,rotate the bottom flat rail under wavey rail,place ring gap about 45* from gudgeon pin,now wind top rail on above wavey bit placing ring gap about 90* from the other gap.Go back astep,the wavy expander gap should be on the opposite side of the piston to the ring gaps.The oil rails may have about 40 thou clearance with no ill effects. Yes they have ashit load of wall tension we used to try and only fit them to worn engines,old 214 bedfords ect where they work very well, motor didn't normally smoke and wore out twice as fast.Iwould not fit them into your nice new barrells,put them on ebay for some other mug.

Thanks guys for your efforts; I think I'll sleep on it all for now though.

Bill, I had hoped that someone out there had actual experience of this set-up. As I said, I couldn't see any other way of fitting it all together and appreciate your confirmation and other info/advice. Your comments on this type of control ring exerting more pressure is quite true - the two compression rings, as you would expect, can easily be squeezed in by finger pressure. I can barely move the oil control ring - it is well lubricated and all the rings move round easily, but the tension of the expander is too much to overcome, particularly when the thin scraper rings dig into the fingers.

Thanks again and any further observations much appreciated.

Bob

Rings

Ah I see it now Bill I'm so used to big marine diesels. The oil ring is totally apart the wavey piece as you call in the middle of the scrapers and that 4th piece holds it all together and makes 1 oil ring. Who says you don't learn something every day.

Sorry Splatt, missed your reply. Regarding excessive pressure, this is just what I was thinking - looks like another small delay then!

Cheers, Bob

I think I've sussed it. By gently bending the flat spring (4th on the right) out and in on alternate peaks and troughs, its diameter can be increased to close to that of the ring groove. Scrapers and wavey bit still under tension but much less outward pressure and more manageable for fitting.

Bob

Hi Bob,the wavey rail should never touch the bores,sometimes the inner expander used to break and the ring would lose all tension,I remember the ends of my thumbs being cut up after building engines using those rings maybe thats why I hate them so much. Is this the product maney supplied or is whats left over from your other barrels,if you have a mismatch of parts you should check with maney that is all compatible,running alloy barrells you want less clearance and the clearance is normally machined into the piston.

Hi Splatt, Yes they are my leftovers but have been given the ok to use by Steve - I simply don't have the cash to go the whole hog. A great shame, as the cost would not have been much more than my total outlay so far. I expect these things happen when a project becomes partly driven by circumstances - I could have stretched to pistons, but my little ends are bored out for the Norvil pistons. Oh well, it will become all Maney in a year or two. I've checked the wavey rail and it does sit below those deadly scraper rings.

Cheers, Bob