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Exhaust manifolds [message #298345]

Wed, 30 March 2016 18:53

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

Is there a way to get new exhaust manifolds for our gmcs?
Don't want to spend the coin for thorleys at the moment.
What manifolds will fit?
Toronado?

Anyone have a good set sitting around?
Mine are welded and still leaking.

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Exhaust manifolds [message #298346 is a reply to message #298345]

Wed, 30 March 2016 19:15

Kingsley Coach

Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada

Karma: -34

Senior Member

Where do you live?

Mike in NS

On Wed, Mar 30, 2016 at 8:53 PM, Justin Brady wrote:

> Is there a way to get new exhaust manifolds for our gmcs?
> Don't want to spend the coin for thorleys at the moment.
> What manifolds will fit?
> Toronado?
>
> Anyone have a good set sitting around?
> Mine are welded and still leaking.
> --
> Justin Brady
> 1976 Palm Beach 455
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>

--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS

Life is too short to hold a grudge; slash some tires and call it even !
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Re: [GMCnet] Exhaust manifolds [message #298347 is a reply to message #298346]

Wed, 30 March 2016 19:22

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

I'm in middle TN.

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Exhaust manifolds [message #298348 is a reply to message #298347]

Wed, 30 March 2016 19:33

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

So something like this?

https://www.opgi.com/cutlass/C240268/?gclid=Cj0KEQjw8u23BRCg6YnzmJmPqYgBEiQALf_XzRxupVbO0w9iIJm6hogcnb_qkqnTC4sJlrmjvgCZH1UaAi-O8P8HAQ

What would be the issues here?
I don't mind a little exhaust work, but are there any major issues I need to be aware of?

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

[Updated on: Wed, 30 March 2016 19:33]

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Re: Exhaust manifolds [message #298349 is a reply to message #298345]

Wed, 30 March 2016 19:40

Gadabout

Messages: 124
Registered: March 2013
Location: Edmonton

Karma: 2

Senior Member

Hi Justin,

I just finished installing a set of toronado manifolds on a local owners GMC, No more exhaust leaks, huge difference.

You may need to replace a section of the exhaust tubing to get the mounting angles to match, this depends on the manifolds you find. I remanufactured the total system from the manifold to the muffler.

Also recommended is the remflex manifold gasket http://www.appliedgmc.com/prod.itml/icOid/670

Finally don't forget the intake exhaust crossover gasket ( were the choke hot air connects to) these are prone to leaking and make the same sound as a leaking exhaust manifold or donut.

Carl Harr : Driver NASCAR Pro Series #2
1978 Gadabout-Restoring
1978 Palm Beach
1976 Glenbrook
Prevost Featherlite H3-45

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Re: [GMCnet] Exhaust manifolds [message #298350 is a reply to message #298348]

Wed, 30 March 2016 19:40

A Hamilto

Messages: 4508
Registered: April 2011

Karma: 39

Senior Member

SONICJK wrote on Wed, 30 March 2016 19:33

...I don't mind a little exhaust work...

Define "little":

http://www.gmcmhphotos.com/photos/diy-header/p43080-diy-header-with-2-and-3-inch-primary-pipes.html

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Re: Exhaust manifolds [message #298351 is a reply to message #298345]

Wed, 30 March 2016 19:43

Rick Williams

Messages: 256
Registered: July 2004

Karma: 0

Senior Member

Try Jim K or Jim B. They have both had used ones in the past. Cinnabar probably has new ones.

Rick

Rick Williams
Bliss, Michigan
1978 Eleganza II

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Re: [GMCnet] Exhaust manifolds [message #298355 is a reply to message #298350]

Wed, 30 March 2016 20:39

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

A Hamilto wrote on Wed, 30 March 2016 19:40

[quote title=SONICJK wrote on Wed, 30 March 2016 19:33]...I don't mind a little exhaust work...[/quote]Define "little":

http://www.gmcmhphotos.com/photos/diy-header/p43080-diy-header-with-2-and-3-inch-primary-pipes.html

That's a lot less work than some of the motorcycle exhaust I've built, but there's a science to headers that I don't claim to fully understand, so in this case I'd rather buy than build haha.

So will any 455 manifolds fit? IE are all 455's the same other than the angle that the exhaust leaves the manifold? I'd really prefer new to used with micro cracks that I'll just have to deal with later.

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Exhaust manifolds [message #298362 is a reply to message #298355]

Wed, 30 March 2016 23:46

A Hamilto

Messages: 4508
Registered: April 2011

Karma: 39

Senior Member

SONICJK wrote on Wed, 30 March 2016 20:39

That's a lot less work than some of the motorcycle exhaust I've built, but there's a science to headers that I don't claim to fully understand, so in this case I'd rather buy than build haha.

So will any 455 manifolds fit? IE are all 455's the same other than the angle that the exhaust leaves the manifold? I'd really prefer new to used with micro cracks that I'll just have to deal with later.

It is not really a header as much as a homemade manifold. Just a thought.

I suspect any Olds 455 manifold will bolt on, just can't say which ones will point a direction that can be plumbed into a muffler on the GMC.

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Re: [GMCnet] Exhaust manifolds [message #298363 is a reply to message #298355]

Wed, 30 March 2016 23:46

jimk

Messages: 6734
Registered: July 2006
Location: Belmont, CA

Karma: 9

Senior Member

Brand new ones are around $390 per side, that is why we sell so many
Headers..
There is a trick to make them work trouble free. We tell you all these over
the phone all day long.

On Wed, Mar 30, 2016 at 6:39 PM, Justin Brady wrote:

> A Hamilto wrote on Wed, 30 March 2016 19:40
>> SONICJK wrote on Wed, 30 March 2016 19:33

...I don't mind a
> little exhaust work...

Define "little":
>>
>>
> http://www.gmcmhphotos.com/photos/diy-header/p43080-diy-header-with-2-and-3-inch-primary-pipes.html
>
>
> That's a lot less work than some of the motorcycle exhaust I've built, but
> there's a science to headers that I don't claim to fully understand, so in
> this case I'd rather buy than build haha.
>
> So will any 455 manifolds fit? IE are all 455's the same other than the
> angle that the exhaust leaves the manifold? I'd really prefer new to used
> with
> micro cracks that I'll just have to deal with later.
>
> --
> Justin Brady
> 1976 Palm Beach 455
>
> _______________________________________________
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> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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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] Exhaust manifolds [message #298388 is a reply to message #298362]

Thu, 31 March 2016 07:58

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

G'Day,

I VAGUELY remember researching the exhaust manifolds on 455's and I THINK there IS a difference between Toronado manifolds and GMC
manifolds.

The manifold for the driver side is unique to the TH-425.

Here's photos of both:

http://www.gmcmhphotos.com/photos/g6894-oem-exhaust-manifolds.html

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426

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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] Exhaust manifolds [message #298389 is a reply to message #298388]

Thu, 31 March 2016 10:15

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

Does anyone have a good source for someone who can "recondition" the stock ones?
IE professionally weld the cracks and surface them back to flat.

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: Exhaust manifolds [message #298405 is a reply to message #298345]

Thu, 31 March 2016 13:16

bwevers

Messages: 597
Registered: October 2010
Location: San Jose

Karma: 5

Senior Member

I welded mine with nickel welding rods.
It didn't last very long before they cracked again.
The metal is very thin after 40 years.

http://www.gmcmhphotos.com/photos/data/6029/medium/Moho_manifold_067-small.JPG

Bill Wevers GMC49ers, GMC Western States 1975 Glenbrook - Manny Powerdrive, OneTon 455 F Block, G heads San Jose

[Updated on: Thu, 31 March 2016 13:17]

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Re: Exhaust manifolds [message #298406 is a reply to message #298405]

Thu, 31 March 2016 13:45

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

bwevers wrote on Thu, 31 March 2016 13:16

I welded mine with nickel welding rods.
It didn't last very long before they cracked again.
The metal is very thin after 40 years.

I'm in the same boat. I tig welded them but they aren't perfectly flat and still leak. I'm sure the weld won't last very long either.

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Exhaust manifolds [message #298409 is a reply to message #298405]

Thu, 31 March 2016 14:02

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

40 year old cast iron exhaust manifolds are at the end of their service
life. They cannot USUALLY be successfully welded. Brazing works fairly well
if the manifolds are properly prepared and preheated to 400° F. before and
during the process. Not a job for amateur welders. Olds cylinder head
manifold mating surfaces also deteriorate over time, especially if exhaust
leaks are allowed to go unattended for too long. One thing that will help
here is proper installation of REMFLEX BRAND exhaust gaskets. They are
quite fragile when handling them, but when installed correctly, they seal
up irregular surfaces quite well. I Run Doug Thorley Headers with remflex
gaskets on my 403 and have been running them since 1998. Over 40000 miles
with no leaks. Don't think stock iron manifolds will do much better than
that. But, your results can vary.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Mar 31, 2016 11:17 AM, "Bill Wevers" wrote:

> I welded mine with nickel welding rods.
> It didn't last very long before they cracked again.
> The metal is very thin after 40 years.
>
> http://www.gmcmhphotos.com/photos/data/6029/medium/Moho_manifold_067-small.JPG
>
> _______________________________________________
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> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Re: Exhaust manifolds [message #298485 is a reply to message #298345]

Sat, 02 April 2016 10:46

A Hamilto

Messages: 4508
Registered: April 2011

Karma: 39

Senior Member

SONICJK wrote on Wed, 30 March 2016 18:53

Is there a way to get new exhaust manifolds for our gmcs?
Don't want to spend the coin for thorleys at the moment.
What manifolds will fit?
Toronado?

Anyone have a good set sitting around?
Mine are welded and still leaking.

http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&th=36553&start=0&rid=2083

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