Quadrajet Throttle Linkage Questions

Discussion in '40- & 55-Series Tech' started by RWBeringer4x4, Apr 13, 2013.

  1. RWBeringer4x4

    RWBeringer4x4 Mechanically Challenged SILVER Star

    Messages:
    1,881
    Location:
    North East, MD
    To any of you guys running a Q-jet on your SBC conversions - I have a question.

    Nearly every quadrajet throttle linkage I have seen has a C-shaped bracket that the throttle cable and the return springs connect to. The return springs generally run back, toward the firewall.

    My linkage has the return springs running forward. They mount to a fabbed up mount welded to the alternator bracket, then, apparently, got hung from wherever the PO could find a spot to hang them from on the accelerator bracket. This seems precarious at best. I've tried to run the springs backward, to the hole in the bracket at the rear of the carb, but, as expected, they then hold the throttle open, instead of pulling it closed.

    Anyone know how to remedy this? Anyone seen this bracket before?

    Thanks!
    Strange Linkage.jpg Springs 2.jpg Springs.jpg
  2. RattleCan

    RattleCan

    Messages:
    234
    Location:
    Black Diamond, Wa
    I think you have the wrong spring(s). Isn't one of those spring supposed to connect on the tang on the firewall side?

    This is what mine looks like if that helps-

    [​IMG]
  3. RWBeringer4x4

    RWBeringer4x4 Mechanically Challenged SILVER Star

    Messages:
    1,881
    Location:
    North East, MD
    Yeah that's like every other Q jet I've ever seen. I tried to mount the springs to the tang on the firewall side as you mentioned, but then they just hold the throttle open...the springs have to run out toward the radiator to properly pull the throttle closed...
  4. fzr400guy

    fzr400guy SILVER Star

    Messages:
    353
    Location:
    San Diego
    Here is a close up shot of my Lokar Quadrajet Linkage setup.

    [​IMG]

    You might want to scrap the setup you have and just buy an off the shelf kit.
    Last edited: Apr 13, 2013
  5. Cdaniel

    Cdaniel Undocumented Mechanic SILVER Star

    Messages:
    2,463
    Location:
    AZ
    You have two springs working against each other. Either take the bottom one off or anchor the bottom one to the back. The setup in rattle cans pic can be found on all kinds of 70s era GM cars. Different throttle arm than yours though. Lokar makes all kinds of ways to do this right/better.

  6. RWBeringer4x4

    RWBeringer4x4 Mechanically Challenged SILVER Star

    Messages:
    1,881
    Location:
    North East, MD
    The springs do work against each other. That's how the PO had them set up. My only guess is that because this carb doesn't have a dashpot, maybe the lower spring is providing resistance so the throttle doesn't close to quickly when I let off the gas? Totally grasping at straws...

    Been looking at the lokar options, just not sure what's compatible or what setup to go with.
  7. RWBeringer4x4

    RWBeringer4x4 Mechanically Challenged SILVER Star

    Messages:
    1,881
    Location:
    North East, MD
    It also seems like Lokar only makes the rear bracket that the cable runs through. I can't seem to find a throttle arm...
  8. fzr400guy

    fzr400guy SILVER Star

    Messages:
    353
    Location:
    San Diego
    I'm running the Lokar system setup for a 700R4 Transmission and my late model Quadrajet.

    Here's a picture of the Lokar setup for your style carb
    [​IMG]
    [​IMG]
    Last edited: Apr 13, 2013
  9. Cdaniel

    Cdaniel Undocumented Mechanic SILVER Star

    Messages:
    2,463
    Location:
    AZ
    Q-jet throttle arms are welded to the shaft. Need a donor carb to change it. I would think what you have can work with an OEM bracket and spring. Time to hunt the bone yard.
  10. RWBeringer4x4

    RWBeringer4x4 Mechanically Challenged SILVER Star

    Messages:
    1,881
    Location:
    North East, MD
    Thanks Cliff. Nothing's ever easy! :bang: What did the OEM Bracket and Spring look like. For the life of me, I can't find a picture of a quadrajet with this throttle arm mounted to an engine.

    Does the return spring have to run forward on these setups?

    Running it back toward the firewall, into the cable bracket, just holds the throttle open, so I image they may have run forward originally...

    If that's the case, maybe I'll just keep the setup I'm running. At the end of the day, it works, it just looks kind of goofy...
  11. Cdaniel

    Cdaniel Undocumented Mechanic SILVER Star

    Messages:
    2,463
    Location:
    AZ
    Here's pics of my OEM setups.

    1st is 70's style on the FJ40
    2nd is 80's style for auto trans with a Lokar cable on my truck
    DSCF0796[1].jpg DSCF0798[1].jpg

  12. RWBeringer4x4

    RWBeringer4x4 Mechanically Challenged SILVER Star

    Messages:
    1,881
    Location:
    North East, MD
    Ok, that "70's style" throttle arm is the same as mine, right? What I am having trouble wrapping my head around is how you can run those springs backward. The rear bracket is just holding the cable in place, right? If so, I would technically be able to do the same thing - but when I run the springs backward it holds the truck at wide-open throttle.
  13. cruiserjunkie

    cruiserjunkie

    Messages:
    2,010
    Location:
    south eastern utah
    Looks like you can set it up same as the 70 linkage photo. Did you try your setup that way. The springs now are counteracting themselves and allowing the return of the primary
  14. RWBeringer4x4

    RWBeringer4x4 Mechanically Challenged SILVER Star

    Messages:
    1,881
    Location:
    North East, MD
    I tried running both springs backward like cliff's first picture (nothing counteracting, both springs running to the same hole in the rear bracket. This held the throttle wide open (springs essentially pulling the pedal to the floor) instead of pulling it closed.
  15. pb4ugo

    pb4ugo SILVER Star

    Messages:
    970
    Location:
    spay-lay-wi-theepi, ohio

    Hook up the springs "backward" like you had them in this description & take a pic so we can see what you are doing.
  16. Cdaniel

    Cdaniel Undocumented Mechanic SILVER Star

    Messages:
    2,463
    Location:
    AZ
    Yeah what he said. Makes no sense if your spring is attached opposite of the cable and both anchored in back
  17. RWBeringer4x4

    RWBeringer4x4 Mechanically Challenged SILVER Star

    Messages:
    1,881
    Location:
    North East, MD
    Sorry guys, I'm in Columbus, OH for a few days, no chance to snap anymore pictures. I mocked up what I did in MS Paint. I removed the forward-running spring in the photo, and ran them backward, as show by the red line. This, obviously, pulled the throttle arm back in the direction of the red arrow, essentially just holding the throttle open.

    I knew this would be the case before I tried it, but I'm trying to wrap my head around why.

    The photo of Cliff's 1970's OEM setup appears to be set up the same way, and working properly. What am I missing?

    Worst case scenario, I'll get some new springs and run them forward, it's not THAT big a deal, I guess. Just curious as to why this setup seems to work in the reverse of every other Q-jet setup I've seen.
    Backward Spring.jpg
  18. Cdaniel

    Cdaniel Undocumented Mechanic SILVER Star

    Messages:
    2,463
    Location:
    AZ
    I believe the point you are connecting the spring to on the arm is actually intended for auto trans kickdown. There appears to be another hole in that arm that might work as intended for a spring point. Might need a shorter one.
  19. Cdaniel

    Cdaniel Undocumented Mechanic SILVER Star

    Messages:
    2,463
    Location:
    AZ
    That throttle arm may be bent out of shape as well. Allowing the spring to pull it over center. Wouldn't be too hard to bend it into a better position
    Last edited: Apr 14, 2013
  20. RWBeringer4x4

    RWBeringer4x4 Mechanically Challenged SILVER Star

    Messages:
    1,881
    Location:
    North East, MD
    Yeah, it's definitely for the trans kickdown - just seemed like an obvious place to hang it and see what happened. The hole you mention is behind the cable but maybe I'll hang it from there and see what happens.

    Also a possibility I suppose, though this seems less likely to me. Seems like it would be awfully hard to bend an arm welded to the throttle body without messing up the throttle body...I guess we'll see when I tear it apart!

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