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Today I measured the new piston rings I will use while rebuilding my old Skoda Estelle engine.

Skoda Set

  • They are new from the Skoda factory (or that's what the box says), but they were manufactured in the late '80s! :) They are in pristine conditions.
  • They are two-piece rings (ring + coil).
  • They are chromed.

  • The manual talks about 0.14 to 0.32mm gap.

    • The 1st (compression) and 2nd rings have less than 0.5mm gaps.

    • However, all the oil rings have gaps around 1 to 1.5mm!

    • Different rings have different gaps: some have almost 1mm, while others are more near 1.5mm.

A Different Set

  • These are new.
  • These are one-piece rings (only rings, no coils, and no groove behind the rings to accommodate a coil).
  • These are the "file-endings-down-to-adjust" kind.
  • These are matte black.

But, I only have 3 of them.

Questions

  1. Can I mix oil ring sets?
    • Can I use the three one-piece rings correctly adjusted and use one of the two-piece rings for the remaining piston? (I could use the one with the smallest gap.)
  2. Should I just use the four two-piece factory rings?

I'm adding some photos here:

Black rings don't fit, but I can file the endings to make them in:

Black rings don't fit, but I can file the endings to make them in

New "factory" oil rings with uneven gaps. I put them together for the picture, so we can see how different gaps they have.

New "factory" oil rings with uneven gaps

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    Stupid question: How are you going about measuring the ring gap on these? Can you give me the specific way you are going about this? – Pᴀᴜʟsᴛᴇʀ2 Nov 7 '16 at 19:01
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    I insert the ring into the liners and push it with an old piston to about 2 inches down the liner. Then I use a feeler gauge in the gap to measure it. – Aram Alvarez Nov 7 '16 at 19:10
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if they are 30+ years old were they kept in oil or some other anti rust / corrosion preservative? if not make sure the rings are still good.

Are these gaps with the new cylinder sleeves? if so then your rings are undersized for the sleeves and you may need bigger piston rings and possibly an oversized piston as well or you need to get different properly bored sleeves. Then if the rings are too tight you can shave them down with one of those small ring grinders.

I would get properly sized rings. I would not use the factory ones which you cannot grind down to the proper size. Are the "black non factory" rings the originals or aftermarket.

Can you upload a picture of all the rings and the rings gap when installed in the cylinder?

I am assuming you are measuring the gap while the ring is in the cylinder


holy cow that is a huge ring gap. How does the ID of the new sleeves measure compared to the ID of the old ones?

wait a minute that bottom image of a cylinder liner, one with all 3 rings in it, looks used are those the new ones you purchased?

It looks like you have factory spec new rings with used bored and then used again sleeves. The black ring looks like it may have been an aftermarket oversized ring. Go measure near the tops (under that small wear lip at the top) and near the bottoms (above the lowest point the top ring goes) usually this means near the middle but not always. do this for each new cylinder liner and each old cylinder liner. Give a list of top and bottom measurements for each. you can then see, if it's readable on the package, how oversized the black rings are and if the factory rings are at all. also post the factory stock id of the cylinder liners. sorry really late so I might have rambled but I hope I get the thought across.


I thought so. those factory rings are probably for brand new sleeves. A 1MM gap is pretty big and will leak oil and allow a significant amount of blowby. Are you sure you cannot find anyone with oversized rings? and I am assuming you have not bored out the cylinders and they are worn.

My best suggestion is to bore out all your cylinder liners so they are straight. Worn cylinder walls can be oval or vase shaped or both this means round new rings will not work well at all. You can have new sleeves made that are factory spec and use the factory rings. I really think you should build this engine from the ground up properly else you will probably end up with something you will not like and it will not last long. below is a list of things you should do:

  • all cylinder walls bored to the same diameter
  • all rings either custom made or purchased to fit this bore. you should see what rings are available first before boring. or get new old stock sleeves that are factory spec.
  • purchase or custom order proper fitting rings
  • purchase properly fitting pistons or use yours if the sidewall to piston gap is acceptable
  • from your other posts this engine sounds worn out so below is otehr items to replace
  • valve guides
  • valves
  • rockers
  • cam bearings
  • main and connecting rod bearings
  • check the crank and turn if necessary
  • balance crank
  • replace rockers if it has any
  • if it has them inspect and replace push rods as necessary
  • steam / chemical clean the block and heads while they are completely disassembled
  • recut / relap valve seats for the new valves
  • replace valve springs with something that is within original spec
  • replace any hydraulic valve parts
  • replace oil pump
  • replace upper bearings on the connecting rods as necessary
  • replace wrist pins as necessary
  • replace all the bolts and studs as they probably are stretched
  • check flatness of the block deck and resurface as necessary
  • check the flatness of the bottom of the head and resurface as necessary
  • double check all the machining work and redo as necessary
  • assemble with more assembly lube than you thought you needed and all new gaskets and seals. Remember your seals need proper clubbing too little clubbing and they will run away out of your engine too much clubbing and you could damage their rubber skin, so club them just enough so they will not move.
  • ignore bad jokes
  • and lastly you need to bang a few knuckles to give blood to the car gods. Hiding your hands in the church of mechanic glove does not always protect you, but is suggested.

if you want to see how out of round your current cylinders are and the other used ones are then stick a new ring in and use a long hair and see if you can slip it through any side of the ring if you can that's not so good and that is where you will get blowby and lots of oil burning.


If you are just looking for it to work right now then do this instead:

  • assemble the head with whatever springs you have use the strongest ones from your collection
  • the valve lapping you have done is probably sufficient
  • you could replace the valve guides but at the very least get new seals
  • put the original cylinder liners, pistons, piston rings, connecting rods, main and connecting rod bearings, piston pins, upper piston bearings. all back in exactly the way they came out. If anything changes it could be bad.
  • I am assuming the engine was running more or less when this rebuild started, the old rings were sealing it enough that there was not too much blow by or oil burning, and there wasn't any major noises or malfunctions with the engine.
  • assemble with lots of assembly lube
  • do not put any part in where it did not go originally as all the parts are worn into the places they were originally. Many parts will not re-wear in and instead could simply damage things or be damaged. This includes orientation of the compression rings if the cylinders are oval shaped.
  • if done correctly you should have wheels for possibly a number of years depending on how soft you drive it. buy a faberge egg set it on your dash loose and if it falls off and breaks you were driving too hard ;)
  • then use a different good block and head and build from scratch to match your skoda rally fantasy machine.
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    Yes, the rings were kept in oil, no rust on them. I'm measuring the rings gap about 2 inches down to the cylinder liner. The factory compression and 2nd rings have good gaps, but the oil rings have bigger gaps. The black rings are from unknown source :), have only 3 oil rings but they can have the gaps adjusted, as I guess they are oversized. I wonder if I can use these 3 oil rings for 3 pistons, and use the better one from the factory set for the remaining piston. Finding new/other rings sets will be quite an adventure. – Aram Alvarez Nov 7 '16 at 19:00
  • and these are with the new liners so there shouldn't be any wear or is this a different engine than your other posts? if one factory oil ring is good and you trust the unknown source then that is what I would do, use 3 and the good factory one. Also how pitted and worn are the edges of the old rings? If they are still useable with a good sealing edge and are round no jagged edges to score your liners I would keep the old ones in oil as well may come in handy if you need another rebuild. Not recommended to reuse them but sometimes you gotta do what you gatta do. – Cc Dd Nov 7 '16 at 20:59
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    So I did this: picked a set of 3 black rings for the first 3 pistons, measured and filed (the oil ring) as needed to get a 0.3 mm gap (manual says between 0.22 to 0.38 mm). For the 4th piston used the compression and 2nd rings from the black set, then the factory oil ring that had the less gap as possible, just a pinch below 1mm. So that's done. The liners: not "new" per se, but much better conditions than the one in the engine. Same with the pistons; I got other used-but-ok set, but they measure exactly like the ones in the engine, and I have big problems trying to extract their C clips. – Aram Alvarez Nov 9 '16 at 23:25
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    Replying Cc Dd edit: that's precisely what I will do but I will assemble with what I have so far, so I get "wheels" and then be able to groove down the city streets finding, repairing and purchasing better parts. I have almost another engine as spare parts, I can rectify the crankshaft, camshaft and have the bearings made for the new measures. I also have a head which needs to get shaved, and will adapt Lada valves to it. I have no way to find new Skoda parts here. The black rings? Those are made by mad lather guys :) using cast iron sewing pipes hehehe. But works, lasts like 5 years normally. – Aram Alvarez Nov 10 '16 at 1:14
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    This engine doesn't have valve stem seals! Interesting, I guess they would always drip down oil after they get slightly worn out. Everything is worn out in this engine, however worked just fine ~13 Km/L, no overheating, very low oil consumption. I'm really thinking into a major project: change the engine, in fact change the engine and transmission, and put it all in the front of the car as cars usually are :) I know it will need a lot of woodworking but I like the idea. I just need to find where I lost my backpack (full of cash) hehehehe...I can't find it!!! – Aram Alvarez Nov 10 '16 at 2:08

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