Compression ring assembly |
Post Reply |
Author | |
JeepSaffer
Member Joined: 26 Sep. 2014 Location: South Africa Status: Offline Points: 1181 |
Post Options
Thanks(0)
Posted: 03 Dec. 2018 at 12:22pm |
I'm researching my first engine rebuild, and have run into a confusion. I'm hoping some of the old hands can set me straight!
The Universal Service Manual para D-33 (g) talks about the compression ring assembly: "While the compression rings are of the same size, they are different in construction and must not be interchanged. Install these rings as shown in Fig 42. The upper compression ring has an inside beveled edge which must be installed toward the piston top. The face of the lower compression ring is tapered approximately 0.001". It all seems pretty clear, right? Then my Hastings rings arrive, with their own installation sheet.
I don't have a scan of it here, but it contains the same information as on their website: Highlighting is mine. One set of compression rings in the set has a "pip", which according to Hastings must go to the top of the piston, which puts the inside bevel down. The Service Manual says the bevel must go up. This is confusion #1. The second set of Hastings rings has no pip and no bevel, which according to them means it can be installed either way. The Service Manual says the lower ring face is tapered which would imply that direction is important. Confusion #2. It is possible that the Service Manual was written for a specific ring manufacturers rings, and other manufactures rings (eg Hastings) don't fit the text? That would certainly explain a lot. But it still seems strange that the Service Manual is very specific in their descriptions, yet don't make any acknowledgement that other ring arrangements may be possible, or that other ring designers and suppliers could have a completely different arrangement. Has anyone used the Hastings rings? Are they good to use? Can anyone confirm that they don't fit the Service Manual description at all and the Service Manual can be safely ignored in favour of the Hastings installation sheet? And lastly that the second compression ring in the Hastings kit is indeed non-directional, and that this is completely OK seeing as the Service Manual text implies BOTH compression rings are directional? Just trying to get this right.... piston rings are not in the kind of place that they are easily corrected. You know, measure twice, cut once and all that....... Thank you, Mike |
|
1948 CJ2A #204853 in South Africa
|
|
mike in oregon
Member Sponsor Member Joined: 17 Jan. 2008 Location: Fall Creek Or Status: Offline Points: 1988 |
Post Options
Thanks(0)
|
I always use the manufacture instructions. and I have used Hasting rings and had no trouble with them. Remember the service manual was wrote in the forty's and the way they make rings have changed for the better (I hope). Good luck with the rebuild.
|
|
MIKE IN OREGON
President of Oregon Flat Fender Club. http://www.facebook.com/pages/Oregon-Flat-Fender-Club/222864787838570 46 CJ2A 38007 46 CJ2A 79863 BANTAM T3-C 25314 |
|
JeepSaffer
Member Joined: 26 Sep. 2014 Location: South Africa Status: Offline Points: 1181 |
Post Options
Thanks(0)
|
Thanks Mike, I have since found more info on what Hastings calls "Torsional Rings". The inner bevel actually provides the torsion to the ring through the asymmetrical cross-section, and can be either at the top or the bottom of the ring, depending on the ring design. Hence the "pip" to indicate top from bottom in installation. The point being that the particular ring design I have is obviously different to the Service Manual, but another design might correspond to the Service Manual. I think I'm good. I did get a head scratch going when I first read the Hastings instructions were completely different to the Service Manual! |
|
1948 CJ2A #204853 in South Africa
|
|
Rus Curtis
Member Joined: 25 Mar. 2010 Location: Alabama Status: Offline Points: 1733 |
Post Options
Thanks(0)
|
Not being an expert but here, being an observer, I'd say yes. This could be a "manufacturer" thing or it could be an "industry" thing. Over the years, it seems natural that products can improve or change with respect to construction - as long as the performance remains (or improves). What I see from your posted images is the edge contacting the cylinder wall appears to be the same. So, different rings, different manufacturers, different generation, different instruction but same installation results. The manufacturer wants their product to work as intended, so following their guidance may be best.
|
|
Rus Curtis
Alabama 1954 CJ3B Bantam T3-C |
|
JeepSaffer
Member Joined: 26 Sep. 2014 Location: South Africa Status: Offline Points: 1181 |
Post Options
Thanks(0)
|
Hi Rus, I agree with your sentiment and what you have posted. One thing to keep in mind is that the taper on the ring edge is massively exaggerated in the images above. In reality is it only 0.001" (according to the Service Manual) so is imperceptible to the naked eye. So although the intention is the same, you have to positively know which way is up and which way is down to install it right. Much more obvious to the naked eye is the bevel on the inside of the ring and so it is very tempting to use this as your guide..... but I now know that this is not usable as an up/down identifier! Both types exist! Bottom line: Follow manufacturers instructions on up/down orientation, do not rely on location of ring bevel.
|
|
1948 CJ2A #204853 in South Africa
|
|
Post Reply | |
Tweet |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |