Home » Public Forums » GMCnet » [GMCnet] Blown Exhaust Gasket
| [GMCnet] Blown Exhaust Gasket [message #73976] |
Mon, 15 February 2010 22:12  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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I've had very good luck using copper exhaust gaskets on 455's. That's why I
was so surprised when I removed the headers from the 455 before removing the
drivetrain. At the top center of the right exhaust manifold there was a
break in the gasket. The conventional wisdom is that one should not tighten
the top center bolts very much to prevent rocking the manifold toward the
top, loosening the bottom, and allowing leakage. That's more commonly said
about iron manifolds than about headers, but is nonetheless what's
recommended. In this case, the top bolt was VERY tight (don't ask me why !)
-- in fact, it was so tight that when the wrench finally move, I slipped,
hit the crankshaft pulley with a tooth, and broke that. :-(
The blown gasket is shown here (no photo of the chipped (false) tooth --
SHE hasn't noticed it so it's not to be publicized).
<
http://www.gmcmhphotos.com/photos/showphoto.php?photo=32460&title=mr-gasket-7170-copper&cat=3056
>
Ken H.
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Blown Exhaust Gasket [message #73977 is a reply to message #73976] |
Mon, 15 February 2010 22:22  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Hope that was all that happened to you.
Some have hurt their arm, chest and face severely on breaking a bolt.
On Mon, Feb 15, 2010 at 8:12 PM, Ken Henderson <hend4800@bellsouth.net> wrote:
> I've had very good luck using copper exhaust gaskets on 455's. Â That's why I
> was so surprised when I removed the headers from the 455 before removing the
> drivetrain. Â At the top center of the right exhaust manifold there was a
> break in the gasket. Â The conventional wisdom is that one should not tighten
> the top center bolts very much to prevent rocking the manifold toward the
> top, loosening the bottom, and allowing leakage. Â That's more commonly said
> about iron manifolds than about headers, but is nonetheless what's
> recommended. Â In this case, the top bolt was VERY tight (don't ask me why !)
> -- in fact, it was so tight that when the wrench finally move, I slipped,
> hit the crankshaft pulley with a tooth, and broke that. :-(
>
> The blown gasket is shown here (no photo of the chipped (false) tooth  --
> SHE hasn't noticed it so it's not to be publicized).
>
> <
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=32460&title=mr-gasket-7170-copper&cat=3056
>>
>
> Ken H.
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Blown Exhaust Gasket [message #73987 is a reply to message #73984] |
Mon, 15 February 2010 22:45 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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On time when I was in college, I had a heck of a time removing a bolt.
I had only my "Jap Flap" thongs on my feet. Without hesitation, I
jumped up and used my heal to loosen the bolt by pushing the wrench
with the thong at my heel. The wrench slipped and my heel caught some
sharp part and I was bleeding like crazy. Took 7-9 stitches.
On Mon, Feb 15, 2010 at 8:35 PM, Ken Henderson <ken0henderson@gmail.com> wrote:
> Yeah, just a little chip off of a nearly-new $2000 bridge. Â As long as it
> stays between me & the dentist (and Y'All, who wouldn't DARE rat me out),
> SHE'll never notice and I won't have to have it fixed. :-)
>
> Ken H.
>
>
> On Mon, Feb 15, 2010 at 11:22 PM, Jim Kanomata <jimkanomata@gmail.com>wrote:
>
>> Hope that was all that happened to you.
>> Some have hurt their arm, chest and face severely on breaking a bolt.
>>
>>
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Blown Exhaust Gasket [message #73988 is a reply to message #73976] |
Mon, 15 February 2010 22:47 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Oooh! You meant one of your toofies. I was sitting here trying
to think of
what kind of tooth was on the crank pulley.
Well, I've had plenty of bloody lips, but never chipped a tooth.
(yet)
Gary
Subject: [GMCnet] Blown Exhaust Gasket
> I've had very good luck using copper exhaust gaskets on 455's.
> That's why I
> was so surprised when I removed the headers from the 455 before
> removing the
> drivetrain. At the top center of the right exhaust manifold
> there was a
> break in the gasket. The conventional wisdom is that one
> should not tighten
> the top center bolts very much to prevent rocking the manifold
> toward the
> top, loosening the bottom, and allowing leakage. That's more
> commonly said
> about iron manifolds than about headers, but is nonetheless
> what's
> recommended. In this case, the top bolt was VERY tight (don't
> ask me why !)
> -- in fact, it was so tight that when the wrench finally move,
> I slipped,
> hit the crankshaft pulley with a tooth, and broke that. :-(
>
> The blown gasket is shown here (no photo of the chipped (false)
> tooth --
> SHE hasn't noticed it so it's not to be publicized).
>
> <
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=32460&title=mr-gasket-7170-copper&cat=3056
>>
>
> Ken H.
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Blown Exhaust Gasket [message #74005 is a reply to message #74004] |
Mon, 15 February 2010 23:56 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| GMCWiperMan wrote on Mon, 15 February 2010 23:44 |
If you know of an impact wrench that will reach the top center bolt on the
right side Thorley header, I'll buy it.
Ken H.
On Tue, Feb 16, 2010 at 12:16 AM, Ken Burton <n9cv@comcast.net> wrote:
>
>
> Next time soak it with Kroil and use a 3/8" drive electric impact on it.
|
I headers and do not remember accessing that bolt as being a problem. I'll have to go look. I might have used a universal joint socket on it. I just do not remember it being a problem.
I'll look next time I'm in there.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Blown Exhaust Gasket [message #74008 is a reply to message #73976] |
Tue, 16 February 2010 05:17 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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so, I read this as -- crankshaft pully --- humm no teeth there, he must
have ment the flywheel ---- wow big problem, wonder why he was back there
---- ??
-- in fact, it was so tight that when the wrench finally move, I slipped,
> hit the crankshaft pulley with a tooth, and broke that. :-(
>
>
then I read this and thought " wow she must have been helping"
well it was really early, and I finally --GOT IT---
> SHE hasn't noticed it so it's not to be publicized).
>
>
just don't make them like they used to. ;>( -teeth that is-
gene
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Blown Exhaust Gasket [message #74018 is a reply to message #74008] |
Tue, 16 February 2010 07:38 |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
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Senior Member |
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I guess it would help you understand the incident if I admitted that I'd
already removed the radiator shroud and the fan, and had my head up between
the engine an radiator with my left arm extended up there pushing on a
"doubled wrench" (a closed end wrench acting as an extension on the
combination wrench turning the bolt). The "crash" was the end event of
probably 30 minutes of trying. At least the bolt then came out. :-)
Ken B., I don't know about your headers, but mine have a tube passing over
that hole too close to even let a standard 3/8" drive socket fit on it --
without a handle. Only an end wrench will fit.
Ken H.
On Tue, Feb 16, 2010 at 6:17 AM, Mr.erf ERFisher <mr.erfisher@gmail.com>wrote:
> so, I read this as -- crankshaft pully --- humm no teeth there, he must
> have ment the flywheel ---- wow big problem, wonder why he was back there
> ---- ??
>
> -- in fact, it was so tight that when the wrench finally move, I slipped,
> > hit the crankshaft pulley with a tooth, and broke that. :-(
> >
> >
> then I read this and thought " wow she must have been helping"
>
> well it was really early, and I finally --GOT IT---
>
>
>
> > SHE hasn't noticed it so it's not to be publicized).
> >
> >
>
> just don't make them like they used to. ;>( -teeth that is-
> gene
>
>
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| Re: [GMCnet] Blown Exhaust Gasket [message #74064 is a reply to message #74055] |
Tue, 16 February 2010 16:38 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Bill,
I got all excited when I found those gaskets on eBay for $22.95 and posted
it to the GMC net.
A colleague more learned than I noted:
Rob, those look like the Mr. Gasket copper gaskets. They may not work
properly for our manifolds. In my case, the gaskets didn't reach to the
bottom of the port on the manifold and the embossed seal was out in the air.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=5898
They reportedly work fine for the Thorley headers, however.
Dave Lenzi makes and sells copper gaskets that fit our manifolds.
Rick "on a cautionary note..." Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
Dave Lenzi can be contacted:
http://www.bdub.net/lenzi/index.html
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Bill Freeman
Sent: Wednesday, 17 February 2010 8:36 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Blown Exhaust Gasket
I got Mr Gasket 7170 copper gaskets for my 69 Toronado but it's openings are
smaller than the ports in the 69 heads.
A raised bead surrounds the inside edge of the gasket's ports so enlarging
to make them fit might compromise the sealing forces.
I used Federal Mogul foil faced gaskets instead which fit the ports much
better than the 7170 copper.
--
Bill Freeman
78 Royale 73 Sequoia
Colerain, North Carolina
http://tinyurl.com/yx7nra
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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: [GMCnet] Blown Exhaust Gasket [message #74157 is a reply to message #73976] |
Wed, 17 February 2010 12:36 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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| Ken Henderson wrote on Mon, 15 February 2010 22:12 |
I've had very good luck using copper exhaust gaskets on 455's. That's why I
was so surprised when I removed the headers from the 455 before removing the
drivetrain. At the top center of the right exhaust manifold there was a
break in the gasket. The conventional wisdom is that one should not tighten
the top center bolts very much to prevent rocking the manifold toward the
top, loosening the bottom, and allowing leakage. That's more commonly said
about iron manifolds than about headers, but is nonetheless what's
recommended. In this case, the top bolt was VERY tight (don't ask me why !)
-- in fact, it was so tight that when the wrench finally move, I slipped,
hit the crankshaft pulley with a tooth, and broke that. 
The blown gasket is shown here (no photo of the chipped (false) tooth --
SHE hasn't noticed it so it's not to be publicized).
<
http://www.gmcmhphotos.com/photos/showphoto.php?photo=32460&title=mr-gasket-7170-copper&cat=3056
>
Ken H.
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Hurt your face huh?? Who'd notice?? 
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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