Quadrajet four barrel trouble.

Discussion in 'General Automotive Tech' started by Dads74, Jun 29, 2024.

  1. Dads74

    Dads74 New Member

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    I have a 1974 Chevrolet Caprice Estate with an original 400 V-8 and Quadrajet four barrel carb. Just recently I have been having some carb issues that I have never had with this car. When I start it cold it starts real nice and runs at high idle like it should but it will not kick down to normal idle. I drive it for a bit and then the idle is normal. I have given the car a look over externally and everything looks as it should. There is no binding of any kind in the carb linkages. Once I have driven the car, the carb runs as it should even after turning it off and starting again. It only does this when in cold start. I rebuilt this carb back in 1995 and it has been perfect in every way until now. I usually put about 500 to 1000 miles on the car every year going to car events. Does anyone have an idea what could be happening. I would appreciate any thoughts on the matter. Thanks and cheers. George.
     
  2. Steve-E-D

    Steve-E-D Well-Known Member

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    Hi George.
    Its hard to tell from your description what exactly the problem is. It is taking longer than normal to go from high idle down to normal idle?
     
  3. Caprice Estate

    Caprice Estate Dads 74 Caprice

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    Hello Steve.
    Yes, it takes much longer to kick down to normal idle. I have to drive the car for it to evenually go down to normal idle.
     
  4. Doghead

    Doghead Well-Known Member

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    It sounds like either a stuck heat riser or the choke is hanging up
     
  5. Steve-E-D

    Steve-E-D Well-Known Member

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    When was the last time you replaced the thermostatic spring in the choke? They get tired and weak eventually.
     

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