Piston rings

Joined
May 21, 2007
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2
Good day to all. My name is David. I have just registerd on this forum but have been reading for a while. I live on Vancouver Island B.C. Canada and have been the owner of a 1972 Combat Roadster since 1978.
I am engaged in a rebuild at the moment and have been blue printing the engine.
I bought a top end kit from Norvil and it contains Piston rings that are different from the ones I have used in the past. They are Italian made,
and the two compression rings are different. One is black and the other shiney.
So my question is. Which one goes in which position, and which way up? They are unmarked.
I am thinking that the black one is the top ring. Has anyone used these rings?
Thanks,
David.
 
Joined
Apr 7, 2004
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1,691
Rings are of a larger diameter at the bottom than the top. With a good square good eyes and a good light you should be able to puzzle this out top from bottom. But in any case you need to call Les on the phone and get the real story right from him. Be sure to check that your ring gaps are generous not minimal. The idea being to keep them from touching when they see heat. Also ask if they are cast iron or not ,the material determines the hone stone used.
 
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Apr 15, 2004
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Hi David, welcome to the forum.

I used those pistons on my 750 rebuild. Be prepared for some fun installing those miserable "spring expander" oil rings :eek:

IIRC, the chrome-plated ring goes on top. I don't recall if they have a preferred orientation but Les could tell you. I thought I had some notes but can't find them at the moment. Perhaps someone else here (L.A.B. are you out there?) knows.

Hey norbsa, I wasn't aware that there are different hone compounds for different ring materials. The old master lets slip another of his secrets, eh? :wink: Whatever my machinist used, it seems to have worked well 8)

Debby
 
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Apr 7, 2004
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Good reading found here http://www.hastingsmfg.com/techtips.htm
It seems we have many pros honing cylinders for cast iron rings using less than 220 grit. That's fine for modern rings but not for cast iron.
What then occurs is that the engine goes through break in and the rings don't get round before the hone is long gone. The bit of oil that slips into the combustion chamber than causes coking that hangs up a valve leading to bent valves. It also lowers the octane of the gas adding detonation to the mix.
A quote form the page above : The finish produced by a 220-280 grit stone is most desirable. The cross hatch pattern should intersect at approximately a 450 angle. Too flat an angle leads to ring spinning which prevents seating the rings.

Probably the most critical part of the deglazing operation is the proper cleaning after deglazing. The residue of honing, if left in the engine, will rapidly destroy all moving parts. It is recommended that engines be cleaned thoroughly with soap and water. Clean with soap and water until the bore can be wiped with a clean white cloth without soiling the cloth. After clean up, oil the area to prevent rust formation. Waterless hand soap also serves as an excellent cleaning agent.
 
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May 19, 2006
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I quite agree with what Debby says about those Italian cast scraper rings. I broke my first ring in about 30 years putting those into my 750 and had to go and borrow a set of ring clamps. :oops: I'd always been one of those "Proper fitters don't need ring clamps" types - Not anymore !
 
Joined
May 21, 2007
Messages
2
Hi everyone, thanks for your help and advice. I called Les Emery of Norvil and he explained the orientation. It turns out that the rings are indeed marked as he said they are I just couldn't see the marking with the naked eye. Somehow writing is getting smaller the older I get.... I had to use a jewellers loup to see the markings but they are there, albeit a bit tiny.
So, chrome ring on top, doesn't matter which way up, next ring cutout facing down and then the oil ring shamfer up. Easy to see with a magnifying glass or younger eyes..
I am gettting some piston ring pliers... I too always did it by hand but rings are too expensive and far away to risk breaking them..thanks again.
I have been setting up the cam timing with a vernier cam sprocket over the past few days and am now tackling the rockers and trying to get them centered on the valves. Lots to do but it is coming along.

The hastings link is great thanks norbsa. You were right Debby, and thanks to 79by100 for your comments supporting Debby. Maybe I won't break any rings..
David
 
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