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Quadrajet Replacement...Mixture Control Solenoid

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by johnny reb, Mar 5, 2003.

  1. johnny reb

    johnny reb 1/2 ton status

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    My 1986 K5 has Q-Jet with the mixture control solenoid. I have recently removed many of the emissions components such as the AIR pump, etc. when installing a new GM 350. Now, I have nothing plugged into the mixture control solenoid on the carb. There are several other vacuum lines that aren't being used either.

    Since I've removed most of the emissions equipment, can I simply switch to a Q-Jet without the mixture control solenoid without any problems? I'm thinking that since I have nothing plugged into the mixture control solenoid, that my mixture isn't being set properly. Can i switch to a manual choke or would I have to keep the electric choke? Which model Q-Jets should I be looking for?
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    You've gotta determine whether you have a mix control solenoid or a dual capacity pump, because it matters.

    Do you have a TPS on the other side of the carb, or only one electrical plug that goes into the carb body?

    If two plugs, you HAVE to change the distributor with the carb, as the carb will run full rich on the primary side and timing won't work correctly. If one electrical plug, the distributor is not "tied in" with the carb, and the carb nor distributor necessarily need to be replaced.
     
  3. johnny reb

    johnny reb 1/2 ton status

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    There is no TPS. Apart from the Idle Speed Control, the Mixture Control Solenoid is the only other electrical plug on the carb.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Without TPS, there is no mixture control solenoid.
     
  5. Doug M

    Doug M Registered Member

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    What we are telling you is you don't have a mixture control solenoid, you have a dual capacity pump. I have heard that without the wires connected to the pump that you will run rich and waste gas. I have seen an air horn for a older qjet without the pump will bolt on to your carb.
     
  6. johnny reb

    johnny reb 1/2 ton status

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    Unless I'm missing something, I don't see a TPS on there.

    [​IMG]
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    No TPS, thats the dual capacity pump. Operation of said device has been posted on this board by me previously.
     
  8. johnny reb

    johnny reb 1/2 ton status

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    [ QUOTE ]
    What we are telling you is you don't have a mixture control solenoid, you have a dual capacity pump.

    [/ QUOTE ]

    [ QUOTE ]
    Without TPS, there is no mixture control solenoid.


    [/ QUOTE ]

    This isn't a mixture control solenoid?

    [​IMG]
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    To kill the other post, but somewhat help with the answer "what year Q-jet should I run", I'll post here.

    It depends on what your engine is, and what you intend to do. A lot of (all?) the early 305 Q-jets are 800CFM's. Plenty for even a healthy BBC.

    The earlier "flat faced" Q-jets, which were in widespread use up until about 1974, are another option, one advantage *probably* being that up to about 1971-72, the idle circuit was different, capable of more adjustment than later ones.
     

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