Choke hot air tube

[carmangary]

This question is about that hot air tube that goes from the back of the carb, down into the intake manifold, and back out to the choke. Is it supposed to be a single tube? Mine is in two pieces and is loose where the connect. One pieces fits into the top of that flange that goes into the intake manifold and seems kind of loose. I'm sure it is very leaky there. So, what's the deal? I looked in the service manual and it doesn't talk about it.

'79 4.3L/260 V8

 

[marcar1993]

It may be that way with 2 tubes.
It really can't be "leaky". All it does is pipe hot air from the exhaust crossover to the choke. No actually exhaust, but hot air off the crossover stove. It shouldn't have holes in the tubes, but at long as the choke operates ok, then everything is fine.

 

[Bonnewagon]

One tube goes from the exhaust crossover well to the carb mounted choke. One tube goes to a clean air source, usually the carb or air cleaner. Clean air is drawn from the source through the well, getting hot, and then into the choke houseing where it heats the choke coil, and on into the carb through a tiny passagway, thus the need for a clean air source. Leaky or loose tubes will delay the choke coil getting hot and prolong choke activation. This why the factory went with electric chokes, they get hot quicker and choke time is reduced. It is an easy backfit to adapt an electric choke coil from a later model to yours.

 

[carmangary]

Thanks or the explanation. It makes sense how it works now. I'm still wondering about that loose fit, though. Next time I am at the junkyard I will try to look at some similar cars for that and see if I can figure it out. Maybe the loose fit becomes tight as the engine heats up and the tube expands.

 

[DrRansom442]

Thanks or the explanation. It makes sense how it works now. I'm still wondering about that loose fit, though. Next time I am at the junkyard I will try to look at some similar cars for that and see if I can figure it out. Maybe the loose fit becomes tight as the engine heats up and the tube expands.

they tend to rust apart, either replace with new (should still be availible through most parts stores) or replace with an electric .... several kits are availible. Just block the manifold off with a cover plate. Jeg's and Summit are probably the best sources for kits/plates.

 

[carmangary]

Thanks for the tip. I will try to find a new heat tube. The electric choke sounds nice but I like to stay stock/original for historical purposes.

 

[DrRansom442]

ahhh so much easier when you can say "we can make it fit" instead of "is it original?" I am trying for "my car is representative of EVERY year of Cutlass" lol

 

[outsider_27]

I understand keeping it original for "historical" reasons, but a 79 Cutlass with a 260 isn't gonna grab 30K at Barrett-Jackson. I will be changing mine to electric choke for ease of operation. I know the hot air choke is fine, but I like the idea of an electric choke. These were pretty common cars in their day. Now they are getting easier to pick up and great to modify to meet your specifications. Have fun with it, learn some things you didn't know before, and most of all, make it yours!

 

[carmangary]

I understand keeping it original for "historical" reasons, but a 79 Cutlass with a 260 isn't gonna grab 30K at Barrett-Jackson.

Yea, I agree with that. But, that isn't my reasoning. I just like fixing up things they way they were originally made. It's just my preference. I have the money to go out and buy a brand new 350 and drop into it but I wouldn't get anything out of that. I'd rather get the crusty old 260 going and drive around listening to the factory stereo.

 

[Bonnewagon]

My factory AM/FM stereo is scratchy as hell and I'm going to replace it. I'm the complete opposite-I change everything to suit me. Anyway that tube is just that, a plain old steel tube and you can replace it or fix it. IIRC if you remove the manifold plate you'll see the tube loops around on the inside and the outer tubes fit into that. I'm sure you can braze it, epoxy it, or just beat it tight. Actually I'm surprised it's not just rusted up solid.