new rings

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  #1  
Old 10-12-10, 11:20 AM
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new rings

I am putting new rings on my pistons and am puzzled by the oil spacers. When the scraper rails are put in place with the spacer they stand well out of the piston wall with seemingly no place to go. I measure their diameter in this configuration at 76.5mm; the bore is 75.5mm. Is this normal, and will everything go into place when the compressor is applied ? I am of course reluctant to do this for fear of damaging something if the spacers are in fact wrong, which I think they might be as they look different from the originals and will not themselves fit squarely in a bore without overlap (the originals just will, and all the other new rings check OK for end gap in the bores). This is my first time doing this job and any advice will be appreciated.
 
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  #2  
Old 10-12-10, 01:29 PM
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Sometimes rings need to be trimmed at the ends for a proper gap. Take the rings out of the piston and put them in the cylinder bore. That'll show you whether you have a gap or not. It is this gap that needs to be within specification. There needs to be some gap or the rings will bind from thermal expansion.
 
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Old 10-12-10, 04:00 PM
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Originally Posted by Kestas View Post
Sometimes rings need to be trimmed at the ends for a proper gap. Take the rings out of the piston and put them in the cylinder bore. That'll show you whether you have a gap or not. It is this gap that needs to be within specification. There needs to be some gap or the rings will bind from thermal expansion.
TOUCHDOWN........... Exactly Right...

Remember to look up the POSITIONS the gaps should be in on the installed piston assembly, and ensure the ring Grooves are clean and free of "Nicks"..... "Test fit The assembvled piston in your ring compressor before sliding them in...The compressor should fit competely around the piston, Letting you know that the rings are not binding in the grooves...
 
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Old 10-12-10, 04:29 PM
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Thank you for your replies. As noted all the regular rings (other than the corrugated spacers) are good sized, with end gaps in spec when placed in the cylinders. I do have the gap locations from a book also, and the grooves have been cleaned out thoroughly. But when the scraper rings are sitting in the groove along with the spacer they are being held out by a shoulder (one for each ring) this center ring has. That is apparently normal. Note the spacer ends are abutted here (in fact there is some colored plastic on the ends so you do not make them overlap) with no gap. So upon compression something will have to give to get the scrapers -- and the spacer for that matter -- down to piston diameter -- and as they have been checked for end gap they will not interfere with themselves. I have never done this before and don't know if this is normal or not. I don't want to damage my piston or the new rings because they may have to be returned.
 
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Old 10-12-10, 06:31 PM
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1. i have no doubt ring groves where properly cleaned, either the old man way (toothbrush and kerosene) or with a special tool, or with a piece of broken ring? so that there is no junk left there to lift rings off the piston?
2. i have not done many, but normally they do settle into the groves down to a specified gap. now, you are referring to "a book" and if it's chilton or haynes, i'd double check with dealer repair department for OEM spec. also, depending on where you bought rings.... there used to be Al's Auto Supply here, now out of biz, and rightfully so, it was suicidal to buy anything from them, such junk it was.
3. i have noticed some very good reminders posted. of course, you know that rings have to have gaps pointed out in 120 degrees increments....
4. the bore was honed, right?
 
  #6  
Old 10-13-10, 02:42 PM
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Thanks again for the replies. I mainly used a piece of broken ring to clean out the grooves (except the one piston that is new) and the cylinders have been honed. I have been well aware of these procedures for some time, just have never actually done them myself before. And I have a long list of bum auto part (and machine shop) horror stories going back 30+ yrs and don't wish to have another one, obviously, which is what I suspect is going on here, too. I think I will try out another ring set and see how that looks now.
 
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Old 10-13-10, 06:22 PM
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yep, sounds like a good idea. it's easy to force something in and bust the engine.
btw, after done breaking it in, replace engine oil. you will have some shavings in it, no need to carry it around in the system.

it's fun project. time taking, dirty and stinky, but fun. all the best.
 
  #8  
Old 10-23-10, 01:28 PM
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I got another set of rings from another source and I was right. The expander/spacer ring in the first set is for a larger bore. If I had tried to compress them it would have damaged something (I didn't measure the rails when on the spacer carefully enough; their diameter there was more like 77.0 mm; more than their free-standing diameter, in fact. The new spacers (which look different still) just fit into a bore themselves, and when installed on the piston with the rails everything can just be compressed down to piston size, or nearly so, by using fingers, like the compression rings can. That was impossible with the first set, which is what made me wonder.
 
  #9  
Old 10-24-10, 04:45 PM
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yes sir! langsam aber sieher! slowly but safely. it was excellent observation and idea.
still, drain engine oil after maybe an hr of running. i'd just let her sit and run for an hr or so. maybe set rpms to about 1200 after 30 mins. for another 30 mins of break in time.
just use some cheap oil for break in. it's a waste anyway.
 
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