The tube is pressed into the manifold. Inside the manifold is a continuation of
the heat tube. The exhaust heats the tube and also the air in it. The choke
should have a small amount of suction to pull the heat to the choke spring.
This suction could be blocked. It is also important that the gasket for the
choke housing be in good condition. I am not positive that the tube is open at
the other end, which is why you can't push air through it. I think that the
heat forces the hot air to rise in the tube.
After years of vibration and heat, the tube is rather fragile where it connects
to the manifold, so be careful. I don't believe that it can be removed without
possibly breaking it off.
Many of these don't work. One thing that can happen is that the part of the
tube that is inside the manifold deteriorates and then exhaust/carbon is
sucked/forced into the choke.
If it no longer can be made to function, an electric choke can be fitted, or a
"choke stove" can be added to the manifold that will send heat through the
external tube. To add more heat, sometimes one of the heater hoses is attached
to a bracket that will hold it against the choke spring housing.
Most of these parts are no longer easy to find. I believe that some early
1980's (FORD) cars had Bakelite housed choke springs with electric heating
elements that I have been told could fit our cars, but I am not certain of that.
That is what I remember about the one on my '56 and I haven't worked on it
since 1974. The choke hardly functions at all. I have it adjusted so that it is
just barely closed when completely cold. It opens very easily, and with a
minimum of heat from the engine, but it does seem to work. My car tends to sit
for long period in between runs, so I just deal with it. The important thing to
me is that it is wide open when the car is warmed up.
Paul
In a message dated 6/8/2004 11:46:05 PM Eastern Daylight Time, GKitterma writes:
> Hello all,
> Has anyone ever tried to clear the automatic choke heat tube on a 354 cu in
>engine?
>
> I have no heat coming through the tube attaching the heat tube to the
>automatic choke housing. Naturally the bimetal thermostatic coil spring
>receives no heat and does not move the choke butterfly. I've tried using
>compressed air (60 psi) to clear it. No luck.
>
> Has anyone actually seen the heat tube apart from the manifold in which it
>resides? Is it open on the manifold end...does it have holes drilled in the
>side of the tube?
>
> I would take mine out and look for myself if I could, but I can't budge it.
>The '56 Service Manual is not too helpful. It says," Remove automatic integral
>choke heat tube from exhaust manifold. (Be careful not to bend tube when
>removing)". There's no mention of how to do it.
> Is it pressed in? Does it screw in?
>
> Does anyone have any experience with this? I don't want to clutter everyone's
>inbox with responses to this sort of arcane question. Email me privately if
>you can help. All
> suggestions appreciated.
>
> Gary Kitterman
> '56 C-73 "Babe"
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