Heat tube from exhaust manifold to carb/choke housing broke off (340ci/Rochester 2GV)

HarryLeSabre

HarryLeSabre

Member
Hi,

just put in new spark plugs and managed to rip off the tube connecting the exhaust manufold to the carburetor/choke housing :-(
Apparently it was badly corroded at this place towards the exhaust anyway and already had some holes here weakening the tube.

Any idea how to reattach the tube? Maybe a silicon tube or copper pipe used as coupling?

How does this tube work anyway? Does it lead exhaust fumes to the choke or is it simply transmitting the heat?

Cheers,
Harry
 
The tube leads to the choke housing that has a port to the manifold vacuum. It goes through the exhaust manifold to outside air. You are correct - it picks up heat in the manifold and brings it to the housing via the fresh air. I used a small brass tube to fix mine. Find a size that is tight and slip it into the pipe and then into the manifold hole.
 
Ah, so its just picking up hot air. Then it will be quite easy to fix. And brass tube is an excellent idea as well!

Thank you!

Cheers,
Harry
 
IF you check the bottom of the manifold you will find a tube ALSO protruding from the bottom. This is the fresh air supply to the upper end of the tubing that broke. IF you look at your carb. there will more than likely be a brass colored tube sticking out the top rear of the carb. It hooks to the metal pipe going to the manifold. It is only a couple inches long & since it sucks in fresh air it never gets hot. So you need a pipe from the top of the carb. & a pipe from the rear of the manifold to the housing on the choke. The O.D. of the pipe is 1/4" which just so happens to be the O.D. of 1/4" brake line tubing. I use the new copper coated tubing. Now once it's PROPERLY repaired you should never have to worry about ti again.

Tom T.

You will need to drill out the broken piece on each end of the manifold. This can be done by using a drill bit slightly smaller than 1/4". DON'T drill down more than about 1/2" & the broken pieces can then be easily removed. To make sure the choke housing is drawing vacuum correctly just start the engine & put your finger over the inlet where the pipe hooks up to. There should be & felt vacuum at that source. IF you cannot really feel any vacuum the choke housing needs to come apart for cleaning.
 
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@tom telesco

Thanks a lot for the suggestion of using brake line tubing - just finished that repair (soldered the piece of brake line to the choke tube) and so far it seems to work! But another question arose: Lets suppose that choke tube had bad corrosion/holes before braking entirely, would that be a "vacuum leak" in regards of the carb, setting the air/fuel mixture to "lean"?

@guyopel

Thanks, but over here (germany) the usual auto parts stores are not having such "special" parts - consider yourself lucky ;-)

Cheers,
Harry
 
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