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Canadian Poncho Homepage -> Canadian Poncho -> General Pre 1958 Canadian Pontiac Discussions -> Rochester single barrel automatic choke
Post Info TOPIC: Rochester single barrel automatic choke
LoveKars


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Rochester single barrel automatic choke
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Purchased a 1956 Pontiac. Got it to run by plugging the connector on the automatic choke (See Photo). It is a 6 cyl with a Rochester BC Carb.  Where should this connector go?



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409Safari


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Don't know exactly but the ''heat source'' must be from the exhaust manifold....
...you didn't ask but, here is a chart for a 1958 model BC....hope this help....


1958 model BC-01.jpg

1958 model BC-02.jpg

 



-- Edited by 409Safari on Thursday 7th of July 2016 01:07:41 PM



-- Edited by 409Safari on Thursday 7th of July 2016 01:08:46 PM



-- Edited by 409Safari on Thursday 7th of July 2016 01:10:21 PM

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GLHS60


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Last part, 64, choke stove assembly.

Dorman had some universal listing kits eg: Dorman 55111

Carb draws heat from exhaust manifold "stove" to activate choke thermostat.

Image from internet.

Thanks

Randy

IM000904r.jpg



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409Safari


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GLHS60 wrote:

Last part, 64, choke stove assembly.

Dorman had some universal listing kits eg: Dorman 55111

Carb draws heat from exhaust manifold "stove" to activate choke thermostat.

Image from internet.

Thanks

Randy

IM000904r.jpg

 

 

...with #61...choke suction tube assembly......Thanks Randy! 



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GLHS60


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You got it.....Pontiac!!

Thanks
Randy

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LoveKars


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Thanks Randy.
The last picture you posted helps a lot. I need to I need to get heat from the exhaust manifold to the choke connector. Doesn't explain why the car stalls unless I plug the choke connection.
It appears that if I use an open tube to the manifold, the stalling problem will still be there. The engine was run to normal temperature and the choke was tried in many positions. There is always vacuum
at that choke connection, and if the plug is removed, the car will stall.
ed

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58 poncho fan


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On my car with the 261 I had a problem of a very rough idle when I purchased it.  Thought it might be a vacuum leak and sure enough the heat tube from exhaust to carb choke being an open vacuum line was the culprit!  After pluging it with a right sized bolt car idled smoothly.  Yes in cooler weather it might take a little bit longer for the auto choke to come off but since I only drive in the summer have no problems.  Give it a try might solve your problem.  Bob.



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long stroke


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Sweet looking 56 you got there, can we learn more about your Poncho. How about a C.P. feature car ? Cheers. George



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Fitz


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LoveKars wrote:

Thanks Randy.
The last picture you posted helps a lot. I need to I need to get heat from the exhaust manifold to the choke connector. Doesn't explain why the car stalls unless I plug the choke connection.
It appears that if I use an open tube to the manifold, the stalling problem will still be there. The engine was run to normal temperature and the choke was tried in many positions. There is always vacuum
at that choke connection, and if the plug is removed, the car will stall.
ed

into your carb choke housing, you've got a piston that move against the spring. The piston move by vacuum. When the spring get hot, it come weak, the vacuum piston operated now is stronger than the spring, it can open the choke butterfly. When the spring get cold, it come stronger and close the butterfly.

So, look if you get the piston in the choke housing, I would not be surprised that this part is missing. If the piston is missing, you lost a lot of vacuum there.

 

Hope this help

 

Fitz. 



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GLHS60


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The piston is vacuum operated and opens the choke slightly when the Engine is started cold with a properly closing choke system. If the closed choke didn't open slightly when first started cold the Engine would flood, black smoke and stall.

The piston is the internal choke pull off, or vacuum break, eternal plastic diaphragm on newer cars, but serves the same purpose.

With the choke tube and stove missing you have a vacuum leak, that's why the carb choke hot air inlet needs to be plugged to run without the tube and stove in place. With the tube and stove in place vacuum draws headed air from the ex. manifold heated stove into the carb choke assembly to unwind the choke thermostat to begin open the closed choke.

As this takes a few minutes, the vacuum piston cracks the choke open as soon as the Engine starts to prevent the already mentioned flooding and black smoke while the Engine is warming up.

Also intertwined is the fast idle system, a genius system of mechanically inter connected parts !!

And the choke unloader, the final driver operated external choke pull off.

A mechanical symphony of automotive genius !!!

Thanks
Randy


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