Q-Jet after recent rebuild question

Discussion in 'General Tech' started by bugzaper, Oct 19, 2018.

  1. bugzaper

    bugzaper Well-Known Member

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    Indeed, you are right.
    Just has me "Baffled" at his point.
    It doesn't act as if it is rich and starts right up after shutting down.
    The exhaust pipe ends are nice and gray not black as if it was rich.
    The plugs are tan (as much as you can read plugs these days...).
    Will re-check for a potential vacuum leak, maybe it's down at the transmission.
     
  2. cadillac512

    cadillac512 Active Member

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    Do you have the Edelbrock steel adapter plate under the carb? The thin gold colored plate that seals the q-jet to the intake properly around the secondary bores? Missing that can cause a vac leak. Might spray some carb or brake cleaner around the area to see if idle picks up.
     
  3. PJ McCoy

    PJ McCoy Active Member

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    when you rebuilt it, did you check to see if the air horn was warped? I know some gaskets will take up a little. Just brain storming with you. I've pulled all may books and internet papers,(printed a manual,lol) trying to help you figure this out. Im sure it simple.
    Im notorious for doing something stupid, like on my 780 Holley, I forgot to plug the vacuum hole at the back of the carb, When I installed the Eddie, I used the fitting in the manafold that was there for the power brakes. Never plugged the carb. set timing, made adjustments. drove it around, I was the man. Until a friend said, Dude? Wheres the hose that should be connected to that carb? I was like, Dude!! there is no hose back there. He said I know, But there should be. He took a picture and sent it to everyone we know.
    Pj
     
  4. bugzaper

    bugzaper Well-Known Member

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    no...
    Didn't know there was one.
    Do you by chance have a pic. or link to see what it looks like.
    I used the "Q-Jet Open Hole" type spacer that came in the rebuild kit.
    That very well could be the problem.
    I'll spray around the base and see what I get.
     
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  5. bugzaper

    bugzaper Well-Known Member

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    Here are a few of the spacers I have, which one would be recommend (or none) for the Cadillac Edelbrock intake.
    Currently the carb is mounted directly to the manifold with an open type gasket only.
    Which (as mentioned) could be causing the issues I'm having as stated above i.e. vacuum leak.
    Still need to do a "Carb. Cleaner Spray Check" to determine a vacuum leak of some kind.
     

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  6. cadillac512

    cadillac512 Active Member

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  7. bugzaper

    bugzaper Well-Known Member

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  8. PJ McCoy

    PJ McCoy Active Member

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    Hey that's the first for me too. Let me know how it works. That's probably it.
     
  9. bugzaper

    bugzaper Well-Known Member

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    Will do!
     
  10. bugzaper

    bugzaper Well-Known Member

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    This carb. is absolutely driving me nuts! :geek:
    I've never experienced these kinds of issues with a "Q-Jet."
    Latest problem (among est many...).
    I pulled the vacuum canister off the distributor to replace it with one that requires less vacuum i.e. 8lbs.
    When I took it off it was "FULL OF GASOLINE."
    It had been hooked up with a vacuum hose to the front vacuum distributor port on the carb., the port that I've always used for distributors.
    The only thing I can think of is that it is pulling gasoline from the float bowl somehow.
    "Baffles" me.
     
  11. Red98422

    Red98422 Active Member

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    Holy crap...I’ve never heard of that before, I wish you the best in your efforts to “tame the beast”

    I know it might be stupid but a couple months ago I was messing with an old monojet and the power brake line was full of fuel....good old Rochester, making mystery fuel leaks for no apparent reasons (in my case it was a sunk float...which doesn’t make much sense for normal carbs)
     
  12. bugzaper

    bugzaper Well-Known Member

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    Just don't know...
     
  13. bugzaper

    bugzaper Well-Known Member

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    Took the carb back off.
    Took it apart.
    Found the float to be wrong and a bit heavy (should be 7 grams) fuel soak issues / old (see pics.) wrong on left - right on right. Both would work if properly weighted. Smaller allows a bit more fuel in the bowl.
    Installed correct float.
    Also.
    Found carb gasket to be leaking vacuum.
    Installed an "Edelbrock" plate and gasket set (as recommended).
    Vacuum leak gone.
    Now.
    Playing around with weights in the distributor as the timing is potentially off and coming in way too early.

    Never ending...
     

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  14. kzhurley

    kzhurley Active Member

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    Good to hear
     
  15. Red98422

    Red98422 Active Member

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    Yes! It’s always something right? Congrats on getting that ironed out
     
  16. bugzaper

    bugzaper Well-Known Member

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    Well....it ain't all "ironed-out" just yet but, getting there.
    Going to pull the primary idle tubes and go with some bigger ones I just ordered.
    Enlarge'n the idle screw holes to about .125.
    And, drill a few more holes here and there.
    Change out a few rods and jets (mostly primary).
    I'll post pictures of the processes when the time comes.
     
  17. bugzaper

    bugzaper Well-Known Member

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    Bit more work this weekend.

    1. enlarged the fuel mixture hole
    2. enlarged the fuel pickup-pullover tubes
    3. installed a .135 fuel inlet valve - needle
    4. re-bushed the primary throttle
    5. (today) will be drilling for additional throttle by-pass air as this particular carb didn't come with it
     

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  18. El Diablo

    El Diablo Active Member

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    What vehicle(s) do you drive?:
    1959 Cadillac Sedan deVille
    Is there any advantage to keeping the Qjet vs swapping it for a Holley?
     
  19. bugzaper

    bugzaper Well-Known Member

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    That is a debate that has no end...
    Personal preference I guess.
    Looking to get the best "MPG" I can get and still have great response.
    I've tried both on this engine and seem to always go back to the "Q-Jet."
    IMO I think General Motors got it right with the "Q-Jet" i.e. Pontiac-Buick-Olds-Cadillac-Chevrolet and others.
    So...(short answer) I just like them!
     
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  20. Monzallac 425

    Monzallac 425 Member

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    X's 2:thumbup:

    Doug in P.R.:cool:
     
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