Author Topic: Indian alloy piston ring issue  (Read 995 times)

Rom

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Indian alloy piston ring issue
« on: June 16, 2017, 04:08:39 AM »
Hi all,

Been a long time since I've been on. The 16/2 from Power Anand has been out of commission for a while. Moved it to a new generator shed and haven't gotten around to setting it up yet.

Anyhow, I bought a load of parts from Power Anand almost 8 years ago. This included some alloy pistons for use in bringing RA Listers back to life out here in the Abacos.

I haven't sold a piston in that time, but had someone contact me a few weeks ago. Needed rings for his real Lister. Well the Indian ones don't fit the OEM piston so I sent him a new alloy piston and rings.

The issue we have found is that the alloy piston has 4 compression ring grooves, along with the scraper groove below the wrist pin. The 4th compression ring groove is larger than the other 3 grooves, same size as the scraper groove. The ring sets I got have 4 compression rings the same size and a scraper. How should I ring the piston?

All 5 alloy pistons i have are the same, with the larger 4th groove. The rings fit correctly on the cast iron pistons for my listeroid. As in the 4th groove is compression ring sized. Did they really make a different set of rings with one larger one?

I sent a email to power anand a few days ago and have not had a reply, are they still around?

Any help would be great
Rom

dieselspanner

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Re: Indian alloy piston ring issue
« Reply #1 on: June 16, 2017, 07:25:44 AM »
Hi Rom

I obtained an allot piston from Dev Engineering that was machined in the way you describe.

As I had a second new set of Listeroid rings I used two scraper rings

After about a dozen short runs - before I got the cooling system sorted - i was turning the engine over by hand and there was a dull clunk, I rotated it gently in both directions and there was no further resistance so I put it down to 'one of those things' and ignored it.

I did a couple of short runs then a decent hour or so, loaded and unloaded, and then popped the big end to check the wear on the new shells, no problem there but there was bits of rings in the sump.
after pulling the piston I found the bottom ring had shattered, it looked like the piston had descended too far, the ring had 'popped' out and guillotined it's self on the return stroke.

There was some minor scoring in the bore, from the bits of ring that were still in the groove but nothing too serious, so I reassembled without the bottom ring. I couldn't see how the event had occurred, you can't see the groove with the piston at BDC and the original Lister cylinder is parallel all the way down, still with the Listard chrome and signs of the original honing.

Anyway it runs quite happily without the bottom ring, there's around another 5 hours on it now.

I'm wondering if it's worth getting the local machine shop to put in another groove, for a compression ring, between the gudgeon / wrist pin and the lower oil ring groove.

Weird, any light on the subject welcome!

Cheers
Stef
Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

dieselgman

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Re: Indian alloy piston ring issue
« Reply #2 on: June 16, 2017, 12:14:48 PM »
There are a number of variations in both piston design and in ring set makeup. Obviously you will need to match them up properly. I have seen both single and double oil-scrapers used on those pistons and your description sounds like you have the 8/1 double oil-scraper variety. Since the ring sets are partially interchangeable, it is common for the Indian assemblers or manufacturers to swap them around without explanation. Obtain the proper ring set for the application.

dieselgman
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Rom

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Re: Indian alloy piston ring issue
« Reply #3 on: June 16, 2017, 03:20:23 PM »
Interesting.

So if I tore into another ring set and gave the gentleman another oil scraper, that should do the job? And just check to be sure the lower scraper doesn't come try to escape the bottom side of the barrel?

Thanks
Rom

dieselgman

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Re: Indian alloy piston ring issue
« Reply #4 on: June 16, 2017, 04:39:23 PM »
I will have to take a look at some of our variations in ring sets here. The oil scrapers are typically of two types: conformable (with spring expander), and rigid. Most of the later alloy piston types used one of each of them for oil control. I have not seen the lower ring ever escape the bottom of the bore after proper assembly- not possible unless the cylinder was lifted off the block and piston/conrod lowered beyond normal travel in its bore.

dieselgman
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BruceM

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Re: Indian alloy piston ring issue
« Reply #5 on: June 16, 2017, 07:49:49 PM »
On the DES 8-1 clone propane conversion project engine, the cylinder was raised about 0.6 inches to lower compression- and we had no problems with rings. So I'm wondering what the heck kind of piston Stef was sent by Dev Precision.

Bruce

listard-jp2

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Re: Indian alloy piston ring issue
« Reply #6 on: June 16, 2017, 08:04:54 PM »
I'm wondering if it's worth getting the local machine shop to put in another groove, for a compression ring, between the gudgeon / wrist pin and the lower oil ring groove.

That would only work if there was sufficient skirt thickness on the piston where you intended to cut the new ring groove, as the casting should have more material on the inside of the piston skirt in the area where the ring grooves are to be machined. Otherwise such a modification would considerably weaken the piston.


All 5 alloy pistons i have are the same, with the larger 4th groove. The rings fit correctly on the cast iron pistons for my Listeroid. As in the 4th groove is compression ring sized. Did they really make a different set of rings with one larger one?


Not in the case of a genuine Lister CS cast iron pistons (all compression rings are 0.125" thick)*, however in the Listeriod world anything is possible! This could be a case of a quantity of modified pistons were produced in order to use up a batch of non standard piston rings.

*Genuine Lister alloy pistons have a different ring configuration to the Lister CS cast iron piston, as it has a keystone wedge top ring which is thicker than the remaining two compression rings again 0.125" thick, for Lister VA applications the top ring was also chrome plated.

Rom

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Re: Indian alloy piston ring issue
« Reply #7 on: June 18, 2017, 11:48:59 AM »
All interesting information.

The customer fitted the piston up with 3 compression and one scraper, leaving the oil groove below the wrist pin without anything.

Will be an interesting test I suppose.

Thanks again
Andrew

dieselspanner

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Re: Indian alloy piston ring issue
« Reply #8 on: June 18, 2017, 01:58:43 PM »
Good point, JP2, and well worth bearing in mind, the top half of an ally piston trying to make it's way through the head is going to be messy.

Andrew, please post up the results of your customers experience ref the lack of a bottom scraper ring, it might save me some work, I've no work for my machine at the present so it won't be clocking many hours.

Cheers Stef 
Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

dieselgman

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Re: Indian alloy piston ring issue
« Reply #9 on: June 18, 2017, 10:25:22 PM »
Parts are readily available for the major variants and original designs.





There are two variations in our stocks for the alloy 8/1 pistons as in above pictures. 6/1 iron piston on right. [presumably] OEM style 8/1 on left, 8/1 with double oil scraper in the middle. The 5-ring sets do NOT interchange with the 4-ring variety because of ring widths and keystone fire-ring used on the OEM style piston.

The 5-ring alloy piston (with 2 oil scrapers) was used throughout the major engine models in the Lister product line for at least 50 years... one of the oil scrapers is soft/conformable -requires an expansion spring [used below the gudgeon pin on 8/1], the other is quite rigid like a compression ring.

We may be looking at a design change from early models to later models by Lister rather than an Indian modification. I believe this to be the case, but have not seen confirmation from original documentation as of yet. [or perhaps simply cannot remember it.]

dieselgman
« Last Edit: June 18, 2017, 10:47:05 PM by dieselgman »
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glort

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Re: Indian alloy piston ring issue
« Reply #10 on: June 19, 2017, 05:29:58 AM »

Looks like the pistons with the lower oil rings would hold the piston much more square in the bore, especially on such a long piston.
Wonder if they would make much difference to wear?

I saw a Vid last week where they tested a V8 engine with std rings and the thin low friction ones. As I guessed, The thin rings made fk all difference.
I call 3 Hp on a 350 CI motor within testing error and insignificant.  I imagine the power Difference with the lower rings would be equally irrelevant.


38ac

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Re: Indian alloy piston ring issue
« Reply #11 on: June 19, 2017, 01:28:17 PM »
Stef, I am going to guess that you damaged that lower oil ring when the piston was pushed into the liner and didnt notice it.

 I have not seen the two oil ring aluminum piston except from India but my experience with 8/1 types is much less than 6/1s .
« Last Edit: June 19, 2017, 07:51:24 PM by 38ac »
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dieselgman

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Re: Indian alloy piston ring issue
« Reply #12 on: June 19, 2017, 03:48:17 PM »
I think you are right Butch... even looking at the latest 1981 edition of the Lister CS 8/1 parts book, they still showed a 4-ring piston assembly 008-04025. They did amend the ring set part number to 574-10990 though while no conformable oil scraper ring is shown at all.

Given the fact that Lister changed to the double oil control rings in the 1960's forward on their other engine models, it is possible that the Indian 5-ring modification is following that technical change. The conformable soft oil scraper ring (with spring expander) is standard fare on the majority of modern engines that I am familiar with. Personally, I like that mod... just need to keep the correct ring stocks handy.

dieselgman
« Last Edit: June 19, 2017, 03:50:53 PM by dieselgman »
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BruceM

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Re: Indian alloy piston ring issue
« Reply #13 on: June 19, 2017, 04:08:10 PM »
Yep, I also think Butch has it right.  I've broken that bottom oil ring myself on the DES 8/1 conversion project. Once the top rings are in, the cylinder wants to come down fast if you aren't holding it back strongly. My homemade ring compressor for my 6/1 wasn't big enough to cover all 5 rings, and had to be shifted after the first 4.  We had that head and cylinder off more than a dozen times getting the compression just right.  Fortunately I caught the cracked ring at the time because I was only holding the compressor and tapping the cylinder down while watching.  If I had been doing it alone- probably not.