Ring Agony

[Superman]

I know some of you think I'm nuts and you're probably right, but I'm still agonizing over whether to use new rings or not. Most of you know my heads are done with new valves, guides, etc. I am re-using the old cylinders and pistons. The cylinders measure .01mm to .02mm wear at the top and up to .04mm at the bottom, where the most wear is. Ovality seems to be minimal. Wear spec is up to .08mm. For those of you who are metrically impaired (like myself), .08mm is just over .003". So, stuff like taper and ovality are in the neighborhood of .001" Pretty good.

Also good is the ring lands. Ring side gap is WAY less than wear spec (.2mm) and WELL within installations spec (.070mm - .102mm). My .102mm feeler gauge absolutley won't fit and my .076mm one will fit, just barely, with drag.

End gap is not as perfect. It depends on what constitutes a "go" or "no go" measurement. Some feeler gauges will not fit, some will go in all the way, and some will go in half way. Does halfway count?

Installation spec is .2mm - .4mm. Wear spec is .8mm.

My .711mm feeler gauge will go in them all. The .762mm gauge will go all the way into three, and will go halfway into one. None of them will accept the .813mm gauge.

So, these rings' end gaps are near wear spec. This engine had excellent compression (190-194 psi on all cylinders). I know some of you think I'm nuts for even considering reusing old rings. I'd be glad to hear from you again. But the several really knowdgeable folks I talk with at times (JW, Warren, etc) know the dangers of using new rings. Even BA tells me in an e-mail I am "on (my) own" with this decision. Again, the engine ran great before.

The cylinders are Alusil. Any comments?

[CamB]

Oh, when I saw the subject I thought you just got the invoice for your parts.

[makaio]

Well since you are on a first name basis with JW, I would go by what he says. I think we all know by know that he knows his stuff.

[Superman]

The experts' advice is either ambivalence or tending toward re-using the old rings. JW, like BA, sees this as a legitimate tough decision. JW generally warns against re-using old cylinders and says new rings can make them smoke. But after measuring mine, he though they have a good chance of accepting new rings without smoking.

And this is really my agony. If ever there were a 183,000 mile engine that could accept new rings, this is perhaps the one. The only thing that is close to spec is the ring end gap. Ring lands are tight. Cylinders taper just a little, but not much. So, I suppose he is right, these cylinders may accept new rings.

On the other hand....my worry is that the new rings and the old cylinders will not like each other. The cylinders are tapered just a bit. My biggest worry is not smoking. It is not poor compression. My biggest worry is that the new rings will eat the old cylinder wall and I'll have a worn out engine in 50,000 miles.

[makaio]

Man that is a tough one! I thought people put new rings in on top-end jobs all the time.

This is my thought super; you only have what $1500 into the project, right? I would put the new rings in, and run it. If you need new pistons and juggs in 50,000 miles than so be it. 50,000 miles for $1500 seems pretty reasonable to me. But then again, that would last me 7-9 years at the mileage rate I'm using my car at.

What kinda of miles can you expect if you use the old rings?

[Superman]

Matt, that's a really good question. If I'm worried about getting 50K miles, then why am I thinking of using rings that are close to wear spec?

[makaio]

I'm no engine builder, nor do I play one on TV. So what you are saying is the old rings are just about worn out? If that is the case, adn you are not goign to put new juggs and pistons on, then put the new rings on and run them.

Now if you were going to put new PC's on, i would go ahead and split the cases, and check the oil pump, and replace the lay shaft bearings. I know that makes the price JUMP , but, it's too big of an investment not to in my book.

[Superman]

Well, I'm, not going to spend $3000 on new P&Cs. Period. If I thought I needed them, I'd shop for a 3.6.

But you have found my other agony. Besides the rings, I wonder if I should look into the case. Rods are off. It would be easy, in theory. And the intermediate shaft bearings may be worn. Probably are. But then, splitting the case just disturbs a factory assembly that according to legend is good for a half-million miles! And I don't think I'll need this engine to go more than another 200K miles. Regardless of what the intermediate shaft bearings look like, that intermediate shaft is not going to stop turning. So, I don't plan to split the case. But I'm getting sidetracked. And verbose.

Rings, gentlemen! And ladies, of course!

[makaio]

Up,Up, and away!

[RoninLB]

No educated opnion only a thought. You seem to have a 50K rebuild in either direction, new/old rings. IMHO, that intermediate shaft bearing may make any dilemma a big MOOT

[dickster]

the old rings are almost worn out - there's your answer.

the layshaft - i have followed the threads saying about worn bearings etc, and although some bottom ends have been good for 1/2 million miles, plenty haven't. 200k is plenty to get from it. i think you should check them. i think would.

the dickster

[rstoll]

Your original problem was only the broken head studs, right? No bottom end problems. So you have the head stud problem taken care of and a fresh top end. Lace 'er up!!! I think Bruce said something in his book to the effect, We never had to rebuild a 3.0 because is was worn out.

[jabb]

Hi Jim

I am going with new rings on my rebuild.... I picked up a nice set of used K&S P&C's that had no rings so that is my only choice...

The wear is minimal on both Piston and cylinders so new rings
for me.... if it only last 50k miles I will save my money toward the next rebuild for a nice set of 3.2 new P&C's

I am doing the bottom end now so in the future I will just have the top end to deal with.

Prentend you lost the rings and go with the new ones

Good Luck

[Thomas Owen]

What do you want from the engine? Trying to put it together for re-sell? No, I did'nt think so. You will probably have it for some time....
My suggestions:
1. SPLIT the CASE! It is not a big step from where you are, and you will have peace of mind.
2. Put in new rings, the old ones are on their way out.
3. Drive it.
Good luck

[Jdub]

Take a hard look at the rest of your car and decide from that angle. If you know there will be suspension, trans, paint, and other fixes in the near future, then put the fresh rings on and button the engine up. If you think you might be moving to a different car, then that's a great reason to minimize cost now.

The old rings might not smoke, but will wear. The new rings might not smoke, but will wear longer. If this were your second top end job, then by all means the case ought to be split both at the mileage you have and the "upper muscle" syndrome of having a top topend and a tired bottom end. But in this case I think you take your chances with the fresh rings and leave it at that. Proper breakin will go a long way towards ensuring a tight engine.

John

[RoninLB]

99.999999999999999999999% of the men on this planet would kill to be having Supermans problem.

[BenWillis]

FYI,

Ii saw a set of 3.6 P&C's on ebay, they are at $500 now.....
Just a thought..

http://cgi.ebay.com/ebaymotors/aw-cgi/ebayISAPI.dll?ViewItem&item=1805374670&r=0&t=0

Ben in SC
80 SC Euro
No Sunroof Coupe

South East Reqion SCWDP, President

[GIBSON]

Super, I've got to chime in here as I'm in the middle of my engine as we speak. With the miles on yours, I'd sure consider the chance that the intermediate shaft bearings are shot. Mine were toast at 98K. At this point, the case can be split in 15 minutes, have it hot tanked, check the main bearings, the interemediate shaft brgs. will be down to copper I'll bet. You'll be glad you did.
My machine shop, German Precision, honed my Nikasil barrels and recommended new rings. With the lands in spec I went ahead and installed a set from Pelican. I followed BA's advise and placed a small amount of oil on them and the cylinder skirt and expect them to seat.
That's my story, I'll let you know how things go when I get it
back together.
Bruce

[pbs911]

I never reused rings, but never tore down a pcar motor, yet. Wouldn't t you have to position the old rings exactly as they were when you took them off the pistons? This seems a little difficult and questions the engine maintaining the same compression.

If you go with the old rings, they WILL wear beyond spec faster. Not tomorrow, but maybe in a coupe of years.

I'd go with the new rings and really work on getting them seated correctly. This is you main concern, right?. With the old rings, you have the concern on wether you maintain the compression, whether they were positioned correctly upon rebuild (if necessary) and in the back of your mind you will know that rings are in your future.

Tough call, but given the choices, I would go with new rings.

[stevef]

Superman, I take it that based on installation specs and wear specs you've given the wear spec seems to be twice the upper limit of the installation spec. Is that a good general statement? I have been going through the same agony but after measuring my worst cylinder and subject to doing the others I don't envy your decision. As good as this whole sharing process is and how the board has allowed us to share experiences I guess when it comes down to it we are still very much on our own and have to make our own decision and have the convistion once a decision is made.
I'm going with John Walker on my situaton. I got less than .0002 inch ovality,and taper (yes tenths!)No ridges, good end gap and lands all with in installation specs. Even if I don't get the rings oriented the way they came out it isn't going to matter. So why am I doing this...oh yer heads. Unfortunately my jubulation cannot mask your agony at this point...little bit like my jubulation when CANADA wins the Hockey Gold this week over the US....sorry