Did 68s Have Stove Pipes???

[Graham57a]

I have seen conflicting info on this so I was curious what the experts think. Two photos below are both survivor 68s with small blocks. One has a stove pipe and the vacuum air cleaner, the other neither. Which one is correct? Or is it possible the stove pipe was a later production truck as they were transitioning to 69??

[Joesjunk]

Correct me if I'm wrong, but I don't believe 68's had a stove pipe

[Joesjunk]

Here's the 16k mile truck I had, it was a 69 and no pipe. I believe they started in 70

[CaptRMW]

The second survivor picture may be a California truck with the smog pump and may have made a difference in the other emission related systems. Chevyland or other Cali members would know better than I.

[1968 baby blue C10]

My uncle and I were talking about this the other day. I know at least the 307 in 68 didn't have a heatshield to even attach one to, there is no place on my ram horns for the full heatshield that I can see. I sure would like to have a factory air cleaner though.

[hewittca]

I don't know anything about what trucks had the stove pipe, but for what it's worth my '68 had the full stove pipe setup on it. As far as I could tell from talking with the PO and looking up casting numbers, my 307 was all original.

[aggiegrad]

I also have an original 68 GMC with 307 with the stove pipe.

[binford]

My 68 with a 6 cly 250ci I needed the heat shield and pipe to pass smog.
Currently no smog required at this time.

Most likely a California only item back in 1968

[Graham57a]

Originally Posted by hewittca

I don't know anything about what trucks had the stove pipe, but for what it's worth my '68 had the full stove pipe setup on it. As far as I could tell from talking with the PO and looking up casting numbers, my 307 was all original.

Corey which plant did your truck come out of?

[FirstOwner69]

My 69 3/4 ton with 350 and Quadrajet which was produced at Fremont, CA, sold to me new and registered in southern California in 1969 never had a stovepipe. That's not to say some 69s didn't have them since smog rules for 1/2 tons may have differed from 3/4 and 1 ton trucks in 1969. Things were evolving rapidly during these years and oftentimes things varied depending upon GVWR.

[HO455]

It may have something to do with where the truck originally sold. I would think it more likely to have a stove in Wisconsin than in California or Florida.

[FirstOwner69]

Originally Posted by HO455

It may have something to do with where the truck originally sold. I would think it more likely to have a stove in Wisconsin than in California or Florida.

Hmmm, interesting thought. I did, however, import the truck with me when I moved to Wisconsin from California in 1971.

[Joesjunk]

My low mile '69 was sold new in Minnesota and it didn't have one.

[Steeveedee]

Originally Posted by HO455

It may have something to do with where the truck originally sold. I would think it more likely to have a stove in Wisconsin than in California or Florida.

It might be the other way around. The stove was used for carburetor preheat to get the choke open sooner. In cold climates, it might be better to slow choke opening so that the engine would run better until completely warmed up. I don't claim this with any certainty; it just seems like it might be logical.

[1968 baby blue C10]

Originally Posted by Steeveedee

It might be the other way around. The stove was used for carburetor preheat to get the choke open sooner. In cold climates, it might be better to slow choke opening so that the engine would run better until completely warmed up. I don't claim this with any certainty; it just seems like it might be logical.

So was it that they only came on vehicles with electric chokes then?

[FirstOwner69]

Originally Posted by HO455

It may have something to do with where the truck originally sold. I would think it more likely to have a stove in Wisconsin than in California or Florida.

Originally Posted by Joesjunk

My low mile '69 was sold new in Minnesota and it didn't have one.

Originally Posted by Steeveedee

It might be the other way around. The stove was used for carburetor preheat to get the choke open sooner. In cold climates, it might be better to slow choke opening so that the engine would run better until completely warmed up. I don't claim this with any certainty; it just seems like it might be logical.

I assumed HO455 was pulling our legs with his post since I stated in my post that my 1969 3/4 ton which was "...produced at Fremont, CA, sold to me new and registered in southern California in 1969 never had a stovepipe". To clarify, I lived in California when I bought the truck. The truck was then first registered there in my name and continued to be through 1971 when we moved to Wisconsin. In summary, it was produced in California and registered there from its first sale in 1969 until late 1971.

[FirstOwner69]

Originally Posted by 1968 baby blue C10

So was it that they only came on vehicles with electric chokes then?

I don't believe any of these trucks ever came with electric chokes. Mine had the choke coil mounted on the top of the intake in a metal housing. The intake had to be warm before the choke would pull off.

[1968 baby blue C10]

Originally Posted by FirstOwner69

I don't believe any of these trucks ever came with electric chokes. Mine had the choke coil mounted on the top of the intake in a metal housing. The intake had to be warm before the choke would pull off.

Oh okay I kind of figured they didn’t, it seemed a little early to me. The choke on my truck was unhooked when I got it and I’ve never used a manual choke before. So how exactly does the stove pipe affect the manual choke?

[FirstOwner69]

It may help heat the intake manifold a bit, but I believe that is primarily the purpose of the heat riser valve located between the driver's side exhaust manifold and exhaust pipe. When the engine is cold, the heat riser valve is closed. In that position, it forces heated exhaust through a crossover in the original intake manifold to the passenger's side exhaust manifold causing the intake to warm faster than normal engine heating would. This, in turn, heats the choke bimetallic spring which opens the choke. The heat riser valve also has a bimetallic spring which allows it to open as it's heated by exhaust.

[1968 baby blue C10]

Originally Posted by FirstOwner69

It may help heat the intake manifold a bit, but I believe that is primarily the purpose of the heat riser valve located between the driver's side exhaust manifold and exhaust pipe. When the engine is cold, the heat riser valve is closed. In that position, it forces heated exhaust through a crossover in the original intake manifold to the passenger's side exhaust manifold causing the intake to warm faster than normal engine heating would. This, in turn, heats the choke bimetallic spring which opens the choke. The heat riser valve also has a bimetallic spring which allows it to open as it's heated by exhaust.

Thanks a lot for the info. I always wondered why the exhaust crossed through the manifold like that. I had no idea manual chokes automatically opened, that’s pretty cool. I need to hook mine up. I remember dad and I took the victor jr. intake off the Camaro when we first got it when I was young, I couldn’t figure out why one port was blocked off and black haha

[FirstOwner69]

Originally Posted by 1968 baby blue C10

Thanks a lot for the info. I always wondered why the exhaust crossed through the manifold like that. I had no idea manual chokes automatically opened, that’s pretty cool. I need to hook mine up. I remember dad and I took the victor jr. intake off the Camaro when we first got it when I was young, I couldn’t figure out why one port was blocked off and black haha

Manual chokes do not automatically open. Post a picture of what you have! I must have misread your post. Not all "automatic" chokes were electric.

[1968 baby blue C10]

Originally Posted by FirstOwner69

Manual chokes do not automatically open. Post a picture of what you have! I must have misread your post.

Okay I think we’re both misreading haha. So you were still speaking of automatic chokes? The exhaust crossover in the manifold has no affect on a manual choke then. Correct?

[FirstOwner69]

Originally Posted by 1968 baby blue C10

Okay I think we’re both misreading haha. So you were still speaking of automatic chokes? The exhaust crossover in the manifold has no affect on a manual choke then. Correct?

Correct. No form of heating will. For the record, here's a picture of the automatic choke on my all original 350 engine with Quadrajet.

EDIT: For others reading this, the unattached wire to the left in the picture is actually the wire from the distributor to the coil. Don't worry, the engine is in storage.

[1968 baby blue C10]

Originally Posted by FirstOwner69

Correct. No form of heating will. For the record, here's a picture of the automatic choke on my all original 350 engine with Quadrajet.

Okay, thanks again. The main confusion was I never knew there were electric chokes, and just heat activated chokes. The pic is helpful too, I will have to compare with mine and see if the 4 barrel swap could possibly be why mine isn’t hooked up, it may have an automatic on it.

Sorry to sidetrack the thread everybody. Was completely unintentional.

[FirstOwner69]

Understood. Not a problem with me!