Decided to hook up the auto choke on my carb (SBF/ 2 brl). I cleaned out the hole in the exhaust manifold so the heat tube would slide in and noticed that it appears to be a blind hole. how can heat travel up the heat tube to the choke housing to open the choke if the hole in the manifold is a blind hole. I assume there is some sort of vacuum assist from the choke housing but with a blind hole how does the heat travel to choke to open the choke?
Controlled vacuum pulls heated air thru the choke. The tube allows enough space to pull air in, heating it before reaching the bi-metallic spring.
I shouldn’t be a blind hole. There were different ways on different cars. The best way I saw on the Fords was the hose coming from filtered air under the air cleaner to a metal tube routed through one exhaust manifold then continuing to the choke and attached to the choke with a brass nut. This tube also had a thermal cover on it to retain heat. There is a little vacuum port in the choke that allows the atmospheric pressure to push air through the system, thus picking up heat and transferring it to the spring in the choke housing. Recreate this system, it will work. Fordor, spent a week in your town back in the day, going to a factory school with the ALF bunch when they were there. Bones
If the hole seems blind, then it could be plugged. I have seen where the tube has broken (inside the manifold) and become clogged with soot. If this is the case you can drill out the manifold at each tube end and replace it. This may require a little brazing unless you can drill a close fit to the replacement tube diameter.
I found a pic on the internet of a mustang with the same manifold and there should be a tube exiting out the bottom to feed air up thru the stove. Time to do some digging while the manifold is out. thanks for the replies.
It frigging has to be a blind hole or you have an exhaust leak. Exactly as 302GMC said is how it works. I've hose clamped a length of tube to the manifold on a couple of rigs that didn't have a hole or the tube was broke off and you couldn't get it out. It just needs the air in the tube heated up or the air that can flow though it heated up to warm the choke spring up
I have seen some with two tubes,one going to the choke thermostat housing and the other to the carb where it would get fresh air.
Blow some compressed air into the top of the tube where it enters the exhaust manifold. You should feel air coming out the bottom of the manifold where the tube exits the manifold. If not the tube is plugged. I have seen tubes of cars that sat for a while, plugged by mud dauber wasps before.
There is a hole drilled through the manifold with a stainless steel fluted tube pressed in it. People liked to get rid of the tube as they thought it restricted the exhaust and they could also burn out. A fix that was often used with manifolds and headers was to wrap some tubing around the outside and wrap that with header tape. Connect one end to the choke and the other to a filtered air source. http://www.mustangsunlimited.com/Mu...ubes/Choke-Stove-Kit-Headers-or-Manifolds.axd
I tried that once on an OT car. It just didn't get hot enough not being in the direct flow of the exhaust. The choke was very late in opening having the heat tube on the outside of the exhaust manifold.
that tube should travel through the manifold. i had one recently that was rotted and the inside of the choke housing was full of soot. i also had one that i needed to add a chamber that clamped to the out side of the manifold because the original set up was too far gone to save. it was a long time ago and i forget why, or what car it was. switch to electric.
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