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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old October 28th, 2022, 01:02 AM
aztec aztec is offline
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Default Exhaust Manifold

I need an exhaust manifold for a 351 V6 #2487598


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Old October 29th, 2022, 06:05 PM
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sclor sclor is offline
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Default Re: Exhaust Manifold

Aztec:
Which 351 do you have? 351e and 351m use larger port than 351c. 351c could therefore use 305 manifold.

If you have large port (magnum), I would check with the thunder v12 folks. The v12's they build are small port and they typically have large port that they would sell since they part out a lot of engines.

Hope that helps.
Regards
Steve
New Orleans b
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Old October 29th, 2022, 08:38 PM
aztec aztec is offline
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Default Re: Exhaust Manifold

Thanks Steve,
Mine is a 351E
I will continue my search.


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Old October 29th, 2022, 08:52 PM
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Default Re: Exhaust Manifold

351e is a large port magnum engine. The thunder v12 folks likely have some from my experience. Here is a link with contact info.

Regards
Steve
New Orleans

https://www.thunderv12.com/
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Old October 30th, 2022, 02:57 AM
aztec aztec is offline
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Default Re: Exhaust Manifold

Thanks again


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  #6  
Old October 30th, 2022, 06:22 AM
BobBray BobBray is offline
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Default Re: Exhaust Manifold

The 351E uses a unique exhaust manifold. It does indeed have the large 'Magnum' ports but it also has the smaller 3 bolt pipe flange like a 305 or 351C. 351M's and other Magnum V-6's usually used the larger 'rib' style exhaust manifold with a large (@3") 3 bolt flange. The 351E exhaust manifold is a bit restrictive, you might not be that much worse off if you port-matched a 305 manifold as best you could. Then again, if you found a couple of 'real' Magnum exhaust manifolds and ran larger diameter exhaust pipes that would be even better than stock. BTW, there were 2 different 351E exhaust manifolds, one with air injection ports and one without.
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Old October 30th, 2022, 11:17 PM
lizziemeister'sV6 lizziemeister'sV6 is offline
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Default Re: Exhaust Manifold

Are the 3" manifolds you're talking about called "I Beams"? I have a pair and it looked like the exhaust pipe clamps to the manifold - these came from a 351 from a larger truck - I used a pair of 351E manifolds and yes - they constrict the exhaust down to the same lead pipe that the non-magnums use. Figured I would use the big I beams when the time comes to replace the pipes from the manifold to the "H pipe" I use.
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Old October 31st, 2022, 04:13 AM
BobBray BobBray is offline
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Default Re: Exhaust Manifold

Quote:
Originally Posted by lizziemeister'sV6 View Post
Are the 3" manifolds you're talking about called "I Beams"? I have a pair and it looked like the exhaust pipe clamps to the manifold - these came from a 351 from a larger truck - I used a pair of 351E manifolds and yes - they constrict the exhaust down to the same lead pipe that the non-magnums use. Figured I would use the big I beams when the time comes to replace the pipes from the manifold to the "H pipe" I use.
Yes, the Magnum manifolds have ribs and are also called I-beam type. Some of the I-beam manifolds have large 3 bolt flanges, some have a flange for a V-band clamp. I think the clamp style are later years.
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