1996-2000 truck stock Cast iron exhaust manifold on 1985 C10

[Geoduck]

I've installed vortec heads on my 1985 305. I'm aware the 85 stock exhaust manifolds don't fit correctly.
My question is; will 1996-2000 Chevy GMC Truck Exhaust Manifolds fit my 1985 C10? Has anyone done this?
I'd like to retain cast iron manifolds. As I understand it headers would add very little to my 305 with a mild "RV" cam.

 

[jh86]

Headers or manifolds for 86k10 350 w/ Vortec heads?

Hello, Anyone have experience with headers or manifolds for 86 K10 350 with Vortec heads? I’d prefer manifolds over headers. Not looking for high performance. Have scoured internet but can’t find a straight answer.

www.gmsquarebody.com

 

[jh86]

What is your emission setup?

 

[bucket]

I've installed vortec heads on my 1985 305. I'm aware the 85 stock exhaust manifolds don't fit correctly.
My question is; will 1996-2000 Chevy GMC Truck Exhaust Manifolds fit my 1985 C10? Has anyone done this?
I'd like to retain cast iron manifolds. As I understand it headers would add very little to my 305 with a mild "RV" cam.

You will probably find that they are too wide and interfere with the frame rails.

With a little bit of cam and the better heads as well, long tube headers would likely provide a large enough bump in mid range torque to probably be noticed by the 'ol butt dyno. Quality headers and gaskets will greatly lessen the chances of experiencing the types of header issues that people tend to b!tch about.

But if you want manifolds, that's fine too. I believe mid 80's L69 or LB9 manifolds would be nearly a direct replacement. I don't remember them having the oddball bolt spacing.

 

[Geoduck]

What is your emission setup?

Jon, I removed all emission equipment. But do have PCV connected of course.

To answer your question. Headers by Summit (SUM-G9006) will fit our truck perfectly with Vortec heads I know this for a fact.
As you know Vortec heads are slightly different than Gen 1 heads. Vortec exhaust runners are about .100 or .125 taller than Gen 1 heads. Gen 1 manifolds will congest exhaust scavenging. Although they would work its far from ideal. Also the Gan 1 right (passenger side) exhaust manifold and head far rear bolt spacing is about an inch farther than on a Vortec head. There would be a serious exhaust leak.

1996-2000 SBC truck exhaust manifolds are made specifically for those heads. Those trucks are very much like our C10. From viewing pictures of those manifolds driver side looks like an easy fit. Passenger side may interfere with firewall.
If you have those manifolds I would be very interested to learn how they fit your C10.

Andy always has good advise. It maybe better to simply go with headers. Jon, your 350 would gain more from headers than my 305 although the 059 heads I have are darn good.

 

[Geoduck]

Thanks Andy, aways appreciate your input.

 

[jh86]

Jon, I removed all emission equipment. But do have PCV connected of course.

To answer your question. Headers by Summit (SUM-G9006) will fit our truck perfectly with Vortec heads I know this for a fact.
As you know Vortec heads are slightly different than Gen 1 heads. Vortec exhaust runners are about .100 or .125 taller than Gen 1 heads. Gen 1 manifolds will congest exhaust scavenging. Although they would work its far from ideal. Also the Gan 1 right (passenger side) exhaust manifold and head far rear bolt spacing is about an inch farther than on a Vortec head. There would be a serious exhaust leak.

1996-2000 SBC truck exhaust manifolds are made specifically for those heads. Those trucks are very much like our C10. From viewing pictures of those manifolds driver side looks like an easy fit. Passenger side may interfere with firewall.
If you have those manifolds I would be very interested to learn how they fit your C10.

Andy always has good advise. It maybe better to simply go with headers. Jon, your 350 would gain more from headers than my 305 although the 059 heads I have are darn good.

I shared that thread because there is a link to another thread that used 8525hkr manifolds and shared pictures. Seemed promising enough that I’ll be ordering to try in about a month.

 

[bucket]

Jon, I removed all emission equipment. But do have PCV connected of course.

To answer your question. Headers by Summit (SUM-G9006) will fit our truck perfectly with Vortec heads I know this for a fact.
As you know Vortec heads are slightly different than Gen 1 heads. Vortec exhaust runners are about .100 or .125 taller than Gen 1 heads. Gen 1 manifolds will congest exhaust scavenging. Although they would work its far from ideal. Also the Gan 1 right (passenger side) exhaust manifold and head far rear bolt spacing is about an inch farther than on a Vortec head. There would be a serious exhaust leak.

1996-2000 SBC truck exhaust manifolds are made specifically for those heads. Those trucks are very much like our C10. From viewing pictures of those manifolds driver side looks like an easy fit. Passenger side may interfere with firewall.
If you have those manifolds I would be very interested to learn how they fit your C10.

Andy always has good advise. It maybe better to simply go with headers. Jon, your 350 would gain more from headers than my 305 although the 059 heads I have are darn good.

Didn't the earlier '91-'97 LT1 heads have a very similar port design? I haven't had any in front of me for many years. The F-body or B-body manifolds could possibly be a decent choice without killing as much power.