jonathan909 Posted December 6, 2018 Share Posted December 6, 2018 I'm sure that this is just me being an idiot, and that Someone Smart (tm) like GD will straighten me out. I'm trying to install these EJ25 pistons with new rings. Squeeze the rings in the compressor, position it, tap it down, and it stops dead before the piston and block tops are flush. The problem is that the cylinder has a slight chamfer at the top (about .010" larger than the cylinder bore) that extends down about .125", the compression ring is hanging up on it, and not ramping into the bore. Is there some trick I'm missing, like using a special thin ring compressor that will seat down into the chamfer rather than sitting up on the block's mating surface? Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted December 6, 2018 Share Posted December 6, 2018 There should not be a significant chamfer on the block. Can you post a picture? We use the wiseco tapered ring compressor sleeves. Makes installation a breeze. GD 1 Quote Link to comment Share on other sites More sharing options...
jonathan909 Posted December 7, 2018 Author Share Posted December 7, 2018 (edited) Don't know whether this shot is good enough to be useful, but you can see the chamfer (it's about .100" top to bottom) fairly well. A quick+sloppy measurement with my dial caliper (where did that digital go....?) says that it tapers out from the wall about .010". Edited December 7, 2018 by jonathan909 Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted December 7, 2018 Share Posted December 7, 2018 (edited) Oh yeah that little taper is normal. You probably need a better ring compressor. You did check ring gap on the new rings right? That's not seriously a 5.25 floppy drive I see in the background is it? The horror! GD Edited December 7, 2018 by GeneralDisorder 1 Quote Link to comment Share on other sites More sharing options...
nvu Posted December 7, 2018 Share Posted December 7, 2018 are you using the ratcheting sleeve compressor? place the piston face up on a flat surface, place the compressor over it and lightly tension it down making sure everything remains square. pick both up and put it them on the block, tap it so the skirt protrudes into the block and the rings are around the last tension band. lightly tap around the top of the compressor and tension a bit more. make sure it's squared and centered. the piston should slot in with moderate tapping. Quote Link to comment Share on other sites More sharing options...
Numbchux Posted December 7, 2018 Share Posted December 7, 2018 10 hours ago, GeneralDisorder said: Oh yeah that little taper is normal. You probably need a better ring compressor. You did check ring gap on the new rings right? That's not seriously a 5.25 floppy drive I see in the background is it? The horror! GD My thought, too. If the rings are compressed enough, it should slide right in. If you didn't check the ring gap, the rings are probably bottoming out before they'll fit in the bore. Otherwise your tool isn't adequate. Quote Link to comment Share on other sites More sharing options...
jonathan909 Posted December 7, 2018 Author Share Posted December 7, 2018 13 hours ago, GeneralDisorder said: Oh yeah that little taper is normal. You probably need a better ring compressor. You did check ring gap on the new rings right? Of course - I'm just puzzled, not stupid. Gap is well within spec (.018), and with it sitting in the chamfer I can see the gap i.e. it's not pinched shut. 13 hours ago, GeneralDisorder said: That's not seriously a 5.25 floppy drive I see in the background is it? The horror! GD Hell yeah! Those are a couple of old legacy PCs (DOS, NT, 2K) I keep around for various not-unreasonable reasons. It's too unfocused to see, but the silver+blue plate over the drive nearest the cylinder is the nameplate from the service console for an ETA Systems supercomputer (CDC spinoff company circa late 80s). You can see an ETA-10 get destroyed in the big computer room shoot-em-up in the first "Die Hard" - it's the Fluorinert-cooled box with the cool plastic dome on top. Quote Link to comment Share on other sites More sharing options...
jonathan909 Posted December 7, 2018 Author Share Posted December 7, 2018 11 hours ago, nvu said: are you using the ratcheting sleeve compressor? place the piston face up on a flat surface, place the compressor over it and lightly tension it down making sure everything remains square. pick both up and put it them on the block, tap it so the skirt protrudes into the block and the rings are around the last tension band. lightly tap around the top of the compressor and tension a bit more. make sure it's squared and centered. the piston should slot in with moderate tapping. No, not ratcheting, just a couple of cheapies. I'm thinking that may be the problem; at the same time, even if the compressor is perfect (e.g. the Wiseco GD mentioned) I still can't see why the ring wouldn't snap open as soon as it enters the chamfer and get trapped just like it is now. Quote Link to comment Share on other sites More sharing options...
whynot Posted December 7, 2018 Share Posted December 7, 2018 when the ring is compressed, and you push it into the cylinder, the compressor is pushed against the block, and the compressor and cylinder wall act as one cylinder then when the rings get into the cylinder they set against the wall of the cylinder, and the compressor falls off On other cars I have always ended up using the ratchet type, I could never hold the compression required and maneuver everything. This is one I use, https://www.oreillyauto.com/detail/b/lisle-4148/tools---equipment-16488/mechanics-tools-16816/engine-tools-17994/bb466241b099/lisle-ring-compressor/19500/4413526/1999/subaru/legacy?q=ring+compressor&pos=0 Quote Link to comment Share on other sites More sharing options...
jonathan909 Posted December 7, 2018 Author Share Posted December 7, 2018 You're missing the point - the chamfer at the top of the cylinder is a larger ID than both the cylinder wall and the compressor, and thus forms a space for the ring to snap into as soon as it leaves the compressor. That's where I'm getting stuck. That's the style of compressor I'm using - with the little clutch. I'm wondering whether surface roughness of the chamfer is the problem, and maybe whether smoothing it a little with emery paper might be enough to let the ring slide down. Quote Link to comment Share on other sites More sharing options...
jonathan909 Posted December 7, 2018 Author Share Posted December 7, 2018 14 hours ago, GeneralDisorder said: Oh yeah that little taper is normal. Perhaps I should word the question differently: If the taper is normal, and your compressor sits on top of the block, how come your rings don't hang up in the chamfer when you insert them? Is my chamfer too rough and in need of a little polishing, should I be greasing it up with assembly lube so the ring will slide down it into the cylinder, or both? Quote Link to comment Share on other sites More sharing options...
nvu Posted December 7, 2018 Share Posted December 7, 2018 push the piston 80% of the way into the block, tighten the compressor a bit more, tap around the edges so the compressor gets into the chamfer, tap the piston in Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted December 8, 2018 Share Posted December 8, 2018 Well my compressor is the exact size of the bore (99.50mm). So when it leaves the compressor the ring snaps neatly into that chamfer., which guides it into the bore. I had problems with tech's folding over the oil control ring wipers with those inexpensive sleeve compressors. Now we use the tapered compressors exclusively and have them for a variety of bore sizes for different engine applications. Company 23 makes an adjustable tapered ring compressor also that is useful for weird overbore sizes. Thanks for the history lesson. I recognized the 5.25's from my early days of software engineering. Those were mostly outmoded by the 3.5's when I was learning assembly back in high school. GD Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted December 8, 2018 Share Posted December 8, 2018 10 hours ago, Numbchux said: My thought, too. If the rings are compressed enough, it should slide right in. If you didn't check the ring gap, the rings are probably bottoming out before they'll fit in the bore. Otherwise your tool isn't adequate. And NO ONE appreciates an inadequate tool. That extra adequacy can mean the difference between a job well done, and an excruciatingly long hand finish. GD 2 1 Quote Link to comment Share on other sites More sharing options...
jonathan909 Posted December 8, 2018 Author Share Posted December 8, 2018 15 hours ago, GeneralDisorder said: Well my compressor is the exact size of the bore (99.50mm). So when it leaves the compressor the ring snaps neatly into that chamfer., which guides it into the bore. I had problems with tech's folding over the oil control ring wipers with those inexpensive sleeve compressors. Now we use the tapered compressors exclusively and have them for a variety of bore sizes for different engine applications. Company 23 makes an adjustable tapered ring compressor also that is useful for weird overbore sizes. I think I have the picture. I'm not doing anything wrong - I just think I have to finesse this thing a little by dressing the chamfer and adding some lube. 15 hours ago, GeneralDisorder said: Thanks for the history lesson. I recognized the 5.25's from my early days of software engineering. Those were mostly outmoded by the 3.5's when I was learning assembly back in high school. GD Heh - I think that dates us. My first assembly course was PDP-11 (useful when I started working with 68000s later), a night course I took a year or two after I got out of high school. Our instructor was a hard case who wouldn't actually let us use the assembler - he made us hand-assemble all the code to make sure we understood the relative branch calculations. Then the object got entered via front panel bit switches. Oh, happy days... Quote Link to comment Share on other sites More sharing options...
jonathan909 Posted December 8, 2018 Author Share Posted December 8, 2018 14 hours ago, GeneralDisorder said: And NO ONE appreciates an inadequate tool. That extra adequacy can mean the difference between a job well done, and an excruciatingly long hand finish. GD Oh, you're good... 1 Quote Link to comment Share on other sites More sharing options...
jonathan909 Posted December 18, 2018 Author Share Posted December 18, 2018 Figured I'd close the loop on this. Issue resolved. There was a PEBTAC (Problem Exists Between Tool and Chair) component in that I (inexplicably) had the top and middle rings swapped. Yeah, stupid, but I don't think it caused the trouble. It was simply that there was a little tiny ridge on the chamfer that was catching the ring, and with each tap of the piston the ring just made it a little bigger. I still don't get what originally caused the ridge to form, but once I dressed it off with a little emery cloth (and corrected the ring order, of course), all four seated in just fine. 2 Quote Link to comment Share on other sites More sharing options...
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