Piston ring question please help
12-30-2006, 11:25 PM
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Piston ring question please help Just started re-assembling my LS1 after finally getting everything together. I open my Akerly & Childs piston rings up and I'm not 100% on which one is compression. The numbers on the individual boxes are:
AC-3853 1.5MM X 3.902 CI HG
AC-2641 1.5MM X 3.902 DM FF .145 Radial Wall
AC-3861 3MM X 3.897 OIL LT
I figure the CI HG the compression, but it has a groove cut on the outer edge like a scraper. The factory ones didn't have this and this is my first LS1 build and just don't want to guess on anything. Also, what kind of ring gap would you recommend? Normally aspirated, MS3 cam, factory heads, NO nitrous, 4000 converter, mostly track time on engine. Thanks for your help.
Chris
AC-3853 1.5MM X 3.902 CI HG
AC-2641 1.5MM X 3.902 DM FF .145 Radial Wall
AC-3861 3MM X 3.897 OIL LT
I figure the CI HG the compression, but it has a groove cut on the outer edge like a scraper. The factory ones didn't have this and this is my first LS1 build and just don't want to guess on anything. Also, what kind of ring gap would you recommend? Normally aspirated, MS3 cam, factory heads, NO nitrous, 4000 converter, mostly track time on engine. Thanks for your help.
Chris
Last edited by CHRIZ28; 12-31-2006 at 12:50 AM.
12-31-2006, 12:15 AM
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Surely someone has dealt with these rings before. Any help appreciated. Like I said one of the 1.5MM is like a normal ring (DM FF), and the other has that cut in section on the outside of the ring I guess to scrape oil from the cylinder walls (CI HG). Thanks.
Chris
Chris
12-31-2006, 01:05 AM
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I know this is probably a stupid question, but I'm afraid to go farther w/o being sure. This is what I have found, the DM FF rings have what looks some sort of different material used I guess for better sealing on the outermost section of the ring (where it meets the cylinder walls). and do not have a punched dot. The CI HG rings have a punched dot on one side and have the cut-in section for scraping oil I guess. I feel retarded for asking, but does anyone know which one is teh compression ring? Starting to think the DM FF .145 radial wall rings.
Chris
Chris
12-31-2006, 01:19 AM
#5
ok, I found it
posted somewhere on the internet in another forum:
"I looked at the Akerly & Childs rings I bought and this is what I have:
Top ring part number is AC-1166 1/16 X 4.380 DM FF
Second ring part number is AC-1506 1/16 X 4.380 CI FF
I am assuming that FF stands for file-fit. I can't figure out what DM or CI mean.
The second ring is completely black and appears slightly porous and feels like very fine emery cloth. I am assuming that this is a moly ring.
The top ring is the same as the second ring EXCEPT that the ring face is silver
instead of black. I don't know if it is chrome or not. It is not "shiny" like I
would expect chrome to be. It looks more like steel that has been sanded with 600
sandpaper.
I have tried to cross reference the part numbers of the rings I have on the
internet with no luck. I read some more about rings and agree that chrome rings
are not what I want. I will call the machinist this week and ask what kind of
rings these are."
posted somewhere on the internet in another forum:
"I looked at the Akerly & Childs rings I bought and this is what I have:
Top ring part number is AC-1166 1/16 X 4.380 DM FF
Second ring part number is AC-1506 1/16 X 4.380 CI FF
I am assuming that FF stands for file-fit. I can't figure out what DM or CI mean.
The second ring is completely black and appears slightly porous and feels like very fine emery cloth. I am assuming that this is a moly ring.
The top ring is the same as the second ring EXCEPT that the ring face is silver
instead of black. I don't know if it is chrome or not. It is not "shiny" like I
would expect chrome to be. It looks more like steel that has been sanded with 600
sandpaper.
I have tried to cross reference the part numbers of the rings I have on the
internet with no luck. I read some more about rings and agree that chrome rings
are not what I want. I will call the machinist this week and ask what kind of
rings these are."
12-31-2006, 01:23 AM
#6
I would agree. The TOP ring is usually barrel faced, which means either direction the same radius rides the wall which is why it is not dotted. The SECOND ring (oil scraper) is directional due to the design of the face which would necessitate the dot.
As far as gaps go this is preference of the engine builder.
My preference would be to go with:
.004" per inch of bore for the top = .016" (3.905" bore)
.005" per inch of bore for the second = .020" YES, WIDER (3.905")
.050-.055" for the oil rails (should be there already)
Hope this helps
As far as gaps go this is preference of the engine builder.
My preference would be to go with:
.004" per inch of bore for the top = .016" (3.905" bore)
.005" per inch of bore for the second = .020" YES, WIDER (3.905")
.050-.055" for the oil rails (should be there already)
Hope this helps
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12-31-2006, 01:25 AM
#8
did some more searching, the DM is DuraMoly or Ductile Iron Moly and the CI is Cast Iron.
edit: HA! I got beat to it!
edit: HA! I got beat to it!
Last edited by Asmodeus; 12-31-2006 at 01:30 AM.
12-31-2006, 09:27 AM
#9
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Oh, man. Thanks so much. I was about to the point of pulling my hair out with these. I bet I googled akerly & childs a million times. Cool, so DM FF is my moly top ring and CI HG is my cast iron second ring which has the dot punched. The dot goes up so the "scraper" cut into the side can pull the oil down. Sorry for the newbie questions.
Chris
Chris
12-31-2006, 11:13 AM
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I've started the fun task of filing these rings. So far I've got .016 on my top ring and .022 on the second ring (files quicker than I thought), and I haven't touched the oil rails, but they are at .028 right now. The GM manual wants .007 to .0271. So should I leave them alone, or take them to the full .050 like helicoil said? Thanks.
Chris
Chris
12-31-2006, 06:54 PM
#11
Rings Go with the GM manual specs for the oil ring, my specs on the oil ring are generic. Especially, if they are measuring .028" now, leave them alone! The top and second ring specs I listed are in line with what a performance LSX engine would like on the street for moderate performance.
12-31-2006, 06:57 PM
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Appreciate it tremendously. Got finished filing (took years it felt like) and now starting to get the pistons assembled and ready to drop in. Guess I'll spend new years here in the shop with the LS1...... Thanks again everyone.
Chris
Chris
