Exhaust Manifold Options

[Kilian]

Hello. I'm new to this site and have a question pertaining to my 1983 GMC C2500. When I bought it, the previous owner had installed tube headers in place of the original exhaust manifolds. One of the header tubes has finally rusted out and I'm thinking of going back to OEM manifolds. Engine is a 350. What GM exhaust manifolds would fit this engine/truck? Does the SquareBody site have a listing of manifold casting numbers by year to look for?

I'd continue to go with headers if they are readily available and affordable. This GMC is my summer farm truck (2WD and a nearly rust-free body) but is scheduled to get restored at some point (waiting it's turn behind a 1959 3800). Thanks for your help.

 

[chengny]

Hello. I'm new to this site and have a question pertaining to my 1983 GMC C2500. When I bought it, the previous owner had installed tube headers in place of the original exhaust manifolds. One of the header tubes has finally rusted out and I'm thinking of going back to OEM manifolds. Engine is a 350. What GM exhaust manifolds would fit this engine/truck? Does the SquareBody site have a listing of manifold casting numbers by year to look for?

I'd continue to go with headers if they are readily available and affordable. This GMC is my summer farm truck (2WD and a nearly rust-free body) but is scheduled to get restored at some point (waiting it's turn behind a 1959 3800). Thanks for your help.

You must be registered for see images attach

Looks like the P/N for LH side is 14050233:

You must be registered for see images attach

You must be registered for see images attach

https://www.ebay.com/itm/85-87-CHEV...371019431044?_trksid=p2385738.m4383.l4275.c10


And P/N for RH side is 14031376:

You must be registered for see images attach

https://www.ebay.com/itm/81-86-GMC-Suburban-V8-5-0L-5-7L-EXHAUST-MANIFOLD-1103R-NEW-/331645386h



Doesn't seem right - until you look at the way the exhaust pipes are layed out:

You must be registered for see images attach

 

[Craig 85]

His truck is a C20. The only thing that could change this is if he has a VIN has an "M" for the engine code. The right manifold would be 14034069.

 

[Charlie]

 

[Kilian]

Thanks for the replies. Was a dual exhaust system an option on my C2500? I'm away from the truck right now but will check the VIN when I have a chance.

Also, were all trucks equipped with catalytic converters? Mine doesn't have one now...just curious if I'll need to install one if I put on the manifolds and then have a shop redo the pipes and mufflers. I've had this truck since 1997 but never really paid attention to some of these details.

 

[Craig 85]

Most 3/4 and 1 tons have heavy duty emissions on V-8 models with a GVW of 8600 or more. Most heavy duty pickups and 3/4 ton Suburbans did not run cats until 1987 and ran regular fuel.

My truck is a California truck and has more emissions than a federal truck. Unfortunately here in California, any gas vehicle 1976 or newer has to be smogged every 2 years. Even if you pass a tailpipe sniffer, you will fail if all emissions equipment is not present. Hopefully your state is different and you don't have to run smog.

 

[HotRodPC]

Most 3/4 and 1 tons have heavy duty emissions on V-8 models with a GVW of 8600 or more. Most heavy duty pickups and 3/4 ton Suburbans did not run cats until 1987 and ran regular fuel.

My truck is a California truck and has more emissions than a federal truck. Unfortunately here in California, any gas vehicle 1976 or newer has to be smogged every 2 years. Even if you pass a tailpipe sniffer, you will fail if all emissions equipment is not present. Hopefully your state is different and you don't have to run smog.

That ain't no ****. You can pass that tailpipe snitter flying colors, but even if you don't have a functioning Thermostatic Air Cleaner, FAIL !!! Me and my buddies shared one just for smog checks. It got passed around. We'd put it on just for smog test, then go back to our Eddy or Moroso Air Cleaner. Also had to remove the headers and go back to the manifolds just for 1 stupid test. That's pretty much why I street/stripped a 64 GMC Truck. Totally exempt. Also why I'm keeping this 6.2 truck by VIN even though it'll have a nasty ass gas engine in it. Though I really hope I never back to Cali, but if I do, I'm ready for their commie asses.

 

[Kilian]

I checked the VIN and it has an "M" code engine. What is the difference between the "L" and "M" code engines? Both are listed at 5.7L and 4BBL carbs.

 

[4WDKC]

Like NCRS restoration or make it look like stock but improve performance while looking stock?

 

[Craig 85]

I checked the VIN and it has an "M" code engine. What is the difference between the "L" and "M" code engines? Both are listed at 5.7L and 4BBL carbs.

"M" is the heavy duty emissions with no cats. They were designed as more of a torque motor than the 1/2 ton truck.

 

[MikeB]

Check out this link to rockauto.com: https://www.rockauto.com/en/catalog...5157,exhaust+&+emission,exhaust+manifold,5860

Looks like they have Dorman #674278 for the left, and two ATP P/Ns for the right--with and w/o A.I.R. ports.

I had a pair of Dormans for 96-up Vortec 350, and they were fairly well made.

 

[Kilian]

What are AIR ports? I noticed the AIR right manifold has a shroud with a port on top, which should align with a tube that hangs down from my truck's air cleaner and that currently just rests on the header pipe. I've always assumed that allowed warm air up into the air cleaner but didn't do anything for emissions control, etc.

 

[4WDKC]

What are AIR ports? I noticed the AIR right manifold has a shroud with a port on top, which should align with a tube that hangs down from my truck's air cleaner and that currently just rests on the header pipe. I've always assumed that allowed warm air up into the air cleaner but didn't do anything for emissions control, etc.

AIR injects clean air into the exhaust to make it pass emissions, they also obstruct flow. If you have no intentions on using them and want better performance while looking stock to most use Ram horn manifolds.

 

[yevgenievich]

What are AIR ports? I noticed the AIR right manifold has a shroud with a port on top, which should align with a tube that hangs down from my truck's air cleaner and that currently just rests on the header pipe. I've always assumed that allowed warm air up into the air cleaner but didn't do anything for emissions control, etc.

the port is different from AIR injection and is to warm up intake when cold. I believe yours should not have AIR emissions on it.