Trouble getting the correct rings - What is going on?

[Nut124]

I have received tree incorrect sets of rings for my Fiat twincam project. One set by Hastings, two by Grant.

Nominal bore is 84mm. Bored to 84.40mm. Ordered the correct diameter pistons from a Fiat supplier. They came with Hastings rings in a box that gapped at 0.024" Got a set from another supplier, Grant mfg. Top ring gapped 0.023" Middle gapped 0.014". They sent me another box from a different mfg lot. The same thing. Top ring gap 0.023" Middle 0.014'.

What is going on with these ring suppliers? All boxes appeared to have the correct oversize p/n on them xxxx.016.

Are the Grant rings any good in general if I managed to get the correct set?

[rebelyell]

perhaps NPR
http://www.npramerica.com/

[BillK]

I have to ask ...... are you absolutely sure your bore size is exactly 84.4mm ? 3.3228 inches ? Double check your bore gauge ? Only reason I ask is because I have BTDT. An extra .001 is going to add .004 to your gaps at that bore size.

[Nut124]

I have to ask ...... are you absolutely sure your bore size is exactly 84.4mm ? 3.3228 inches ? Double check your bore gauge ? Only reason I ask is because I have BTDT. An extra .001 is going to add .004 to your gaps at that bore size.

That is a good question. I do not have a bore gauge. The bore was bored by a shop to fit 84.40 pistons some years ago and again checked and honed by another shop to fit 84.40 pistons. I did measure the pistons and they do measure about 84.35 it seems.

They do not fit in the bore with a 0.0024" feeler gauge.

And, the two sets of Grant rings have had the 2nd ring gap at 0.014" which sounds about right. Top ring gap was 0.023 in both sets. Not right?

[AC sports]

What do the piston tops say?
If they are Persan 8mm dome pistons, it will be either:
84.34 + 0.06mm or in a recent case I came across they were 84.36 + 0.06mm in which case your bore ends up 84.42mm . That 0.02mm translates to 0.02 x pi or 3.1415 = 0.06mm excess in ring gap.
To be honest the supplied hastings rings have never gapped correct in my bores either. Even at the correct bore diameter, measured with a bore gauge. Also the top ring is cast. Not something you want on a high revving Fiat TC.
I found some Mahle rings I was using with those pistons a while back.
Now I generally only used forged. Either JE or CP.
Let us know what you find. I struggle here in Europe to find standard ring packs for them.

[BillK]

That is a good question. I do not have a bore gauge.

I think the first thing you need to do is absolutely verify the bore size. There must be a machine shop close to you that can measure it for you.

Also, do you have an actual factory service manual that shows the correct ring gaps ? the couple of sources that I found showed .0118 - .0177 top and .0078 - .0139 2nd

I use a fair number of Hasting rings and they are usually pretty close on end gaps for the applications that I am doing.

I would call Hastings and ask what they set the end gaps to for that particular ring set. Their tech response has not been that great since Dawn retired but you should be able to get an answer.

[Nut124]

Thanks for the suggestions, again.

The shop that did the block had the new pistons and they said the bore was just right but did not give me an exact number.

I do have the factory manual. The manual shows testing piston to bore clearance with a feeler gauge, which I did and it was spec.

Grant Rings support said they would send me the correct rings. I do kind of wonder about their Q control a bit.

What do folks think of Total Seal gapless rings? They do show a set for my application?

What are the TS gapless rings made of? Steel?

Hastings and Grant both suggest 3-4 thou gap per inch of bore, which would be 10-13 thou in my case. I'm thinking 13 is good for top ring.

I did check the NPR Nippon Rings catalog and talked to them. There are some NPR top rings for Toyota that would be the same dimension but they all seem to be steel/chome. I'm not sure that is what I want.

[modok]

Get the next size up and file to fit. 84.5 might be a lot more common size, close enough to file.

Total seal sells all kinds of rings. So, they are made of...whatever they say they are made of. They might even make what you want custom....but you could probably buy a lot of grant rings for what that's going to cost.

Do not let the gap tell you want kind of ring to use. i would rather have a loose gap than than a crappy ring.

[PackardV8]

Smokey Yunick told me fifty years ago, "Don't worry about ring gap a few thou too loose. You'll never notice that. Now, a few thou too tight; that'll kill ya."

[engineguyBill]

Total Seal should be able to supply the correct rings for this application, be sure to verify the actual bore diameter as BillK has pointed out. Wiseco should be able to supply a set of NPR rings for this application as well.

[Mark O'Neal]

Smokey Yunick told me fifty years ago, "Don't worry about ring gap a few thou too loose. You'll never notice that. Now, a few thou too tight; that'll kill ya."

Smokey also said it was impossible to run a 6.000 rod in a 406 Chevrolet.

Moe wrote him a letter and asked him to please stop. It was our #2 seller.

[Mark O'Neal]

There is nothing inherently wrong with Grant. Radial tension is a bit high in my experience.

It is the coolest factory to tour in this industry. The world thing is a Rube Goldberg machine. It's absolutely incredible.

While we're on the subject, is Deves still around? They used to make them to order for strange stuff. That may solve your problem.

[Nut124]

There is nothing inherently wrong with Grant. Radial tension is a bit high in my experience.

It is the coolest factory to tour in this industry. The world thing is a Rube Goldberg machine. It's absolutely incredible.

While we're on the subject, is Deves still around? They used to make them to order for strange stuff. That may solve your problem.

I finally received the correct rings from Grant today. Top ring gap is 12-14 thou out of the box.

I talked to Frank at Deves. They could make the rings in a week. In my previous web searches Deves never did show up in the search results. They need to improve their web presence.

Radial tension: The new Grant rings have considerably less radial tension than the rings that came out of the engine. The old rings look bright, shiny, polished. Would a cast ring look bright, shiny after 20 years or were they steel rings?

[Nut124]

OK. I'm not a fan of the Grant oil ring spacer spring at all.

The oil ring is a 3-piece design where the spacer ring both separates the two thin oil rings and provides radial pressure. The ends of the spacer spring are marked in two different colors and they shall not overlap in the groove when installed.

However, as received, I tried installing the oil rings multiple times and invariably, the spacer ring ends fail to butt and jump to overlap. This creates a situation where there is inadequate radial clearance, excessive pressure, for the oil rings at the point of overlap and lack of radial pressure elsewhere around the bore.

I just spent about 45minutes working on the spacers, filing a small groove at one end for the other end to sit in so they butt together rather than jumping to overlap.

What are the odds of a typical shop getting these installed correctly without spending hours tweaking? Not good IMHO.

[superpursuit]

I can install a full set of V8 rings onto the pistons, including the 3 piece oil rings, in just a few minutes as I think most people on this site could. This style of oil ring is by far the most common type with millions upon millions being used.



Allan.