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AFB Choke


Chasander

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The hot air pipe that suppose to move the choke to the vertical position is not getting hot.  (The circuit through the exhaust manifold is intact) There is not vacuum present at the choke fitting. The piston under the cover moves freely and I’ve sprayed cleaner in the passage ways. How much vacuum should I be seeing and what to do next. 

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1 hour ago, Chasander said:

The hot air pipe that suppose to move the choke to the vertical position is not getting hot.  (The circuit through the exhaust manifold is intact) There is not vacuum present at the choke fitting. The piston under the cover moves freely and I’ve sprayed cleaner in the passage ways. How much vacuum should I be seeing and what to do next. 

Blocked tube between choke housing and carb body? Also I believe between the two there should be a tiny rubber ‘washer’ as we call in the UK - maybe it’s shitfed or broken away therefore removing the vacuum?

 

i inherited a mangled hot air choke system ..I mean physically mangled....changed over to electric...perfect ever since...no longer original I admit but it starts in the morning!😀

 

cheers

 

kev

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  If there is no vacuum at the threaded nipple there could be problems in several areas...as Kevin suggested, there is an oring/gasket between the choke housing and carb body which seals the vacuum passage at carb body to choke housing junction....also be sure you have the circular gasket between choke cover and choke housing.

 It is also common for the vacuum passage in the carb body to plug up with carbon. If you remove the choke housing the passage is a straight shot from the choke housing area through the carb body to a plenum in the center of the carb body which is exposed to intake manifold vacuum. I have cleared this passage with the carb still installed on the manifold but it might be easier and worth the extra time to remove the carb and clear the passage on the bench.

Tom Mooney

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4 hours ago, 1965rivgs said:

  If there is no vacuum at the threaded nipple there could be problems in several areas...as Kevin suggested, there is an oring/gasket between the choke housing and carb body which seals the vacuum passage at carb body to choke housing junction....also be sure you have the circular gasket between choke cover and choke housing.

 It is also common for the vacuum passage in the carb body to plug up with carbon. If you remove the choke housing the passage is a straight shot from the choke housing area through the carb body to a plenum in the center of the carb body which is exposed to intake manifold vacuum. I have cleared this passage with the carb still installed on the manifold but it might be easier and worth the extra time to remove the carb and clear the passage on the bench.

Tom Mooney

I had a great teacher 😀

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