| Piston Rings [message #270241] |
Fri, 23 January 2015 16:04  |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
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I got my 455 back from the machine shop ready to assemble.
I'm wondering if the Hastings rings I bought have too much oil ring tension.
Is there a recommended ring package that works best for the GMC?
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: Piston Rings [message #270242 is a reply to message #270241] |
Fri, 23 January 2015 16:18  |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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You didn't get rings with the pistons? I thought you usually got those a set.
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Piston Rings [message #270243 is a reply to message #270241] |
Fri, 23 January 2015 16:30 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
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I bought an engine kit 2nd hand of Ebay.
It had 8 forged pistons, rings and bearings for $300.
The pistons are TRWs L2390F + .030.
The rings are cast iron Hastings. But I was thinking of upgrading to moly.
I measured the forced required to push the piston down in the cylinder
after using the ring compressor and installing one piston.
I takes around 20 pounds of force...... This seems like a lot to me.
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: Piston Rings [message #270251 is a reply to message #270241] |
Fri, 23 January 2015 17:13 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
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Jim,
It's a three piece oil ring and I sprayed the cylinder with WD40.
I measured .023" gap with a feeler gauge, top ring.
So I thought there must be some better parts out there.
Thanks for the feedback.
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: Piston Rings [message #270258 is a reply to message #270241] |
Fri, 23 January 2015 18:04 |
Cadillackeeper
Messages: 464
Registered: October 2012
Location: Fort Lauderdale
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Sound like a great e bay score!!!!End gap is crucial and it Will take Quite a while for the babys to seat in and get used to each hole.When it finally seats in you should be Rockin for many years to come..
77 455 Elaganza II and 67 Animal, Built 500 Powered Eldo
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| Re: Piston Rings [message #270266 is a reply to message #270241] |
Fri, 23 January 2015 19:20 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Excellent buy, that!
I've a question for the gurus though. When I was building flat motors, Mac (flat motor guru) taught us >NEVER< twist a ring during install. We always used a ring expander and dropped them over the piston without any twisting. Your guru says twist them on. I've always installed without twisting. So:
Is there much of a difference in aviation and auto rings in this regard?
Which is the correct method of installing them?
Does it really make a damn one way or the other?
Inquiring minds want to know.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Piston Rings [message #270267 is a reply to message #270266] |
Fri, 23 January 2015 19:38 |
James Hupy
Messages: 6806
Registered: May 2010
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The oil control rings pictured are steel with a phosphate coating on the
wear surface. They can be twisted as pictured. If you try that with the top
or second ring, you can easily break them. I prefer to use a ring expansion
tool. When my hands were tougher, I would use my thumbs and first and
middle fingers to spread open a ring until it would fit into the
appropriate groove. I broke a few until I developed the skill necessary to
do this. It definitely is a learned hand skill, and all people do not
posses it, nor ever will. That is why there are experts, and others that
trust them to do for them what they themselves will never be able to. Lots
of other trades have similar situations. Reading about it on the Internet
is not the same thing as developing the skills necessary to do it. Just
look at Kerry's copper maiden. Stand in awe, and appreciate greatness when
you see it.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Jan 23, 2015 5:21 PM, "Johnny Bridges" wrote:
> Excellent buy, that!
> I've a question for the gurus though. When I was building flat motors,
> Mac (flat motor guru) taught us >NEVER< twist a ring during install. We
> always used a ring expander and dropped them over the piston without any
> twisting. Your guru says twist them on. I've always installed without
> twisting. So:
>
> Is there much of a difference in aviation and auto rings in this regard?
>
> Which is the correct method of installing them?
>
> Does it really make a damn one way or the other?
>
> Inquiring minds want to know.
>
> --johnny
>
> --
> '76 23' transmode Norris upfit
> Braselton, Ga.
>
> "Sometimes I wonder what tomorrow's gonna bring when I think about my
> dirty life and times" --Warren Zevon
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
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| Re: Piston Rings [message #270270 is a reply to message #270241] |
Fri, 23 January 2015 20:16 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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True dat - which is why I used the tool. And breakage would be a concern, they're brittle as hell. Probably why. Mark them 'airworthy' and you add a couple of zeroes to the price. And, I don't think I wanna take a chance on a busted ring where the ability to get out and walk ain't there. So, answer - It doesn't really make a damn as long as you don't bust one.
I stand in awe of Kerry's metalworking ability.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
[Updated on: Fri, 23 January 2015 20:18] Report message to a moderator |
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| Re: [GMCnet] Piston Rings [message #270278 is a reply to message #270270] |
Fri, 23 January 2015 22:01 |
Kosier
Messages: 834
Registered: February 2008
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Not exactly, Johnny. If you read the instructions that come in the ring
package, they will tell you to ALWAYS use a ring expander.
Spiraling the rings onto the piston can put a twist in them that will
prevent sealing properly.
Gary Kosier
77 PB w/500 Cad
Newark, Oh
-----Original Message-----
From: Johnny Bridges
Sent: Friday, January 23, 2015 9:16 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Piston Rings
True dat - which is why I used the tool. And breakage would be a concern,
they're brittle as hell. Probably why. Mark them 'airworthy' and you add
a couple of zeroes to the price. And, I don't think I wanna take a chance
on a busted ring where the ability to get out and walk ain't there. So,
answer - It doesn't really make a damn as long as you don't bust one.
--johnny
--
'76 23' transmode Norris upfit
Braselton, Ga.
"Sometimes I wonder what tomorrow's gonna bring when I think about my dirty
life and times" --Warren Zevon
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| Re: Piston Rings [message #270280 is a reply to message #270241] |
Fri, 23 January 2015 22:13 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
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The bigger the piston (larger the diameter), the less relative twist to the ring when installing by the "twist" method. Try it sometime and you will find that there is also a minimal amount of expansion needed to get it over the top of the piston because most of the ring is within the grove. Been doing it this way since 1969, never broke a ring or had one break after install. Look at how much a ring needs to be expanded with a tool over the top....a lot of stretch compared to twist. More important though is placement of the ring on the piston as the last pic in the series shows. Placement of ring end gaps on assembly at 90* to the pin puts them on the thrust sides of the cylinder and may increase blowby and oil consumption. That is why ring ends should be at or as close as possible to being over the pins, with the top two 180* from each other. General wisdom has said that rings will move on the piston and seek their own spot, so it supposedly doesn't matter where they are placed on assembly. My experience when disassembling motors that we built was that the rings were exactly where we put them on assembly as noted in that last slide.
But then, this is all just my relatively informed, off the cuff, back yard mechanic, gut level, eyeball it up and guestimate, opinion....that's all...
Larry
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] Piston Rings [message #270286 is a reply to message #270280] |
Fri, 23 January 2015 23:50 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Larry,
First of all I went to MM X-7525 to see if there were any instructions there and on page 6A-48 I found:
"RING IDENTIFICATION AND INSTALLATION - For service ring specifications and detailed installation instructions, refer to the
instructions furnished with the parts package."
Next I went to MM X-7625 and found NADA and MM X-7725 had the same instruction as noted above for MM X-7525.
I have my feet in both camps as far as this discussion goes because I have used both methods.
Let's examine your method first. I believe using the word "twist" is a bit of exaggeration I reckon a better word would be
"spiraled."
Using your photos as a reference I'd guess the distance from the top of the piston to the bottom of the second compression ring is
about 1/2 inch. I would state that the second compression ring is "spiraled" half an inch not "twisted. I cant see how that would
damage the ring and make it fail. The top ring is even less. Keep in mind every time the cylinder fires there is an explosion that
puts HEAPS more stress on the rings.
When I have used a ring expander I sit the ring on top of the piston and expand it SLOWLY t just enough to get it over the piston. I
agree that using the ring expander changes the shape of the ring more than your method.
I reckon that as long as you're careful not to actually break a ring either method will work just fine.
On Harley's I used to spread the gaps out 120° apart. When I'd take an engine apart I'd find that the rings were not where I put
them. That could be because they were in a "Milwaukee Vibrator."
Regards,
Rob M.
Sydney, Australia
-----Original Message-----
From: Larry
The bigger the piston (larger the diameter), the less relative twist to the ring when installing by the "twist" method. Try it
sometime and you will find that there is also a minimal amount of expansion needed to get it over the top of the piston because most
of the ring is within the grove. Been doing it this way since 1969, never broke a ring or had one break after install. Look at how
much a ring needs to be expanded with a tool over the top....a lot of stretch compared to twist. More important though is placement
of the ring on the piston as the last pic in the series shows.
Placement of ring end gaps on assembly at 90* to the pin puts them on the thrust sides of the cylinder and may increase blowby and
oil consumption.
That is why ring ends should be at or as close as possible to being over the pins, with the top two 180* from each other. General
wisdom has said that rings will move on the piston and seek their own spot, so it supposedly doesn't matter where they are placed on
assembly. My experience when disassembling motors that we built was that the rings were exactly where we put them on assembly as
noted in that last slide.
But then, this is all just my relatively informed, off the cuff, back yard mechanic, gut level, eyeball it up and guestimate,
opinion....that's
all...
:)
--
Larry
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Piston Rings [message #270295 is a reply to message #270241] |
Sat, 24 January 2015 09:37 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Bob - are Total Seal the rings which have an overlapping step at the ends?
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Piston Rings [message #270383 is a reply to message #270247] |
Sun, 25 January 2015 14:02 |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 11
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Johnny The gap less rings over lap were the gap normally is. Thus it is a total seal. The gap on rings that have the gap. Really let more threw then you would think. I put one of my engines that I just assembled on a dino Wed. To break it in. Started it up. Let it run at 2500 RPM with a good load on it for 1 hour. Then with the carb wide open, and full load at 8.000 RPM. It produce 252.4 HP at 6800 RPM. It's 164 cubic inch Corvair engine. No turbo or nitrus. Then ran a compression test. They were all around 235 PSI. I built a 403 for a GMC four years ago. Started it up. Had it at 2500 RPM for the hour with a medium load. Then 1 hour at a heavy load at 4500 RPM's. Those headers were bright. Compression test was ( as I recall 255 ). No special oil, or high volume oil pumps. Did put in oil that had the proper zinc. Used GM's assembly lube. Street, or track. Build it perfectly clean to proper specs. And balance it. That's the trick to a good rebuild. I've never had to ta
ke one of my rebuilt engines apart for repair. My personal track engines come apart every 1000 miles of track time for inspections. Bob Dunahugh Member GMCMI 78 Royale
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