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Old 01-24-2023, 09:22 PM   #1
Furno68C20
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292 exhaust manifolds

I’m currently swapping a 292 in place of a 250. 68 Truck originally had a 250. The 292 I have has a 3” 3 bolt triangular exhaust manifold flange. This causing a problem since the truck has a 2” 2 bolt flange.

From the research I’ve done I should be able to use a 250 exhaust man that will fit a 292 head and then mate to the OEM exhaust.

Did the 292 come with different exhaust manifolds based on what size the truck was? C10/2030 - 2” manifolds: c50/60 3” manifolds?
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Old 01-24-2023, 10:43 PM   #2
67 twins
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Re: 292 exhaust manifolds

Quote:
Originally Posted by Furno68C20 View Post
I’m currently swapping a 292 in place of a 250. 68 Truck originally had a 250. The 292 I have has a 3” 3 bolt triangular exhaust manifold flange. This causing a problem since the truck has a 2” 2 bolt flange.

From the research I’ve done I should be able to use a 250 exhaust man that will fit a 292 head and then mate to the OEM exhaust.

Did the 292 come with different exhaust manifolds based on what size the truck was? C10/2030 - 2” manifolds: c50/60 3” manifolds?
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Be aware that you are probably going to have to redo the head pipe anyway. Since the 292 block is 1 3/4 inches taller the exhaust is going to hit the frame crossmember before the flange comes up high enough to bolt up. That's what happened on my swap.
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67 C20 292 (originally a 250)4speed longbed fleetside w/original wooden bed=my project truck
67 C10 283+.060 (so a 292 as well)T5 swapped longbed fleetside=my DD
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Old 01-24-2023, 11:52 PM   #3
Wrenchbender Ret
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Re: 292 exhaust manifolds

You are exactly right. The larger manifold came on the larger trucks. 1 1/2 tons & up. The 250 manifold will fit the 292 engine but the larger manifold is better. The small manifold is restrictive on a 292 engine. It causes warpage & cracks in the smaller manifolds.
You will need to fab a exhaust pipe extension or have a muffler shop make it up.

George
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Old 01-25-2023, 09:40 PM   #4
Furno68C20
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Quote:
Originally Posted by Wrenchbender Ret View Post
You are exactly right. The larger manifold came on the larger trucks. 1 1/2 tons & up. The 250 manifold will fit the 292 engine but the larger manifold is better. The small manifold is restrictive on a 292 engine. It causes warpage & cracks in the smaller manifolds.
You will need to fab an exhaust pipe extension or have a muffler shop make it up.

There’s always some modification to do. There is a break in the exhaust pipe under the driver door. I’ll bring that piece along with the manifold to have fab up.

Thanks for the info here.

George
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Old 01-26-2023, 12:29 AM   #5
'68OrangeSunshine
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Re: 292 exhaust manifolds

I have been running Clifford headers since 1978 on my '68C/10 Stepside, but my Calif-stock 292 was originally equipped with the same exhaust package as a 250, Plus A.I.R.
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Old 01-26-2023, 10:34 AM   #6
Palf70Step
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Re: 292 exhaust manifolds

My opinion is go with 12bolt.com manifolds. Best exhaust setup I feel for any Chevy inline six.
https://www.12bolt.com/store/p153/Ex...0-250-292.html
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