Edelbrock accelerator pump linkage

General Mopar Tech Discussions

  1. junkpile

    junkpile Well-Known Member

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    I was told you can bend the accelerator pump linkage rod to get a faster shot to get rid of a mild bog.

    My question is, what way do you bend the rod and what is the results? I have never done this before but I am curious. I would like to improve a slight bog at WOT.

    FYI running 750 on a 440 with 484/284 cam .043 squirters linkage in "rich" hole.
     
  2. Garys1969RR

    Garys1969RR Well-Known Member

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    I just re built a couple of AFBs for my tunnel ram. Same animal. To get more volume of pump shot, the linkage rod needs to be closer to the Pivot Point near the accelerator pump plunger. This results in it moving further, which results in an increased displacement due to more plunger travel. Kind of like stroking a motor.
     
  3. junkpile

    junkpile Well-Known Member

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    My linkage is in the hole closest to the carb body. someone suggested actually bending the link rod to the pump plunger. They did not say what way but I am assuming that if the rod is longer it will push the plunger further down increasing the duration of the shot slightly. This may help my issue, but not sure the direction to go of if there is a certain distance I need between the ends of the link rod in question.

    Old school mechanics have good advise, but sometimes they don't relay it clearly, especially when talking in passing
     
  4. Garys1969RR

    Garys1969RR Well-Known Member

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    May not hurt to experiment with it. If it starts higher, it will end up higher too. And vice versa.
     
  5. Garys1969RR

    Garys1969RR Well-Known Member

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    Try to post a picture of the linkage on the carb, so we can get a better idea of what's going on. There may be some other issue going on here, like too lean in the secondaries or not enough timing advance
     
  6. dvw

    dvw FBBO Gold Member FBBO Gold Member

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    Closest to the choke will deliver fuel earlier. Bend the rod only if necessary to get .500" plunger height measured from the top of the pump plunger to the top of the lid. Any taller than .500" will uncover the accelerator pump well inlet causing fuel to go back into the bowl.
    Doug
     
    Last edited: Feb 13, 2018
  7. lewtot184

    lewtot184 Well-Known Member

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    get rid of the .043" squirter.
     
  8. oldbee

    oldbee FBBO Gold Member FBBO Gold Member

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    Usually one of the three holes is all you need like Doug says, you may have other problems.Bending the rod almost never needs to be done.
     
  9. rumblefish360

    rumblefish360 Well-Known Member

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    Bending the rod is recommend in the instructions as per Carter/Federal Mougal to correct the position of the plunger in the well and the position of the height of the plungers stem above the carb.

    It doesn’t add extra fuel.

    Changing the squirter would help. Experiment!
     
  10. lewtot184

    lewtot184 Well-Known Member

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    too much fuel can cause a flat spot in acceleration the same as not having enough fuel. the difference is an over rich condition doesn't spit up thru the carb like lean does. there also could be an ignition curve issue with that cam. float levels and fuel pressure can cause problems.
     
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    • dvw

      dvw FBBO Gold Member FBBO Gold Member

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      Bring the float level up to 7/32". The main circuit will start earlier. Will not flood at 6psi or less
      Doug
       
    • moper

      moper Well-Known Member

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      You cannot effect any change in the shot's speed by adjusting the rod. You can add volume by using the inner-most hole in the arm because like was said - you're pulling the plunger up more by doing so. If you want to change the speed of the shot (and lessen it's overall duration) you have to change the squirter. Only by making the outlet bigger or smaller can you change the time it takes the pump volume to pass.
      The 284/.484 MP cam is a turd in most installs. If it was not degreed, it would be worth the effort to go back in and do it. Run it a couple degrees advanced will greatly help the low-speed performance. Also look at the timing curves. More initial, limited centrifugal, and in the right rpm range will go a very long way to helping a "carb" problem.
       
    • 451Mopar

      451Mopar Well-Known Member

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      I was thinking that same thing. Often a bog is caused by the fuel level being too low.
       
    • lewtot184

      lewtot184 Well-Known Member

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      I upped the float level on my quads from the recommended 7/16" to 3/8" and noticed a difference.
       
    • Garys1969RR

      Garys1969RR Well-Known Member

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      I agree. Sounds more like a float level, ignition timing, or some other tuning problem. When does the bog occur? Like between 3/4 to full throttle? There are some weighted valves below the sec venturis that open slowly when you kick the secondaries in. I know if the weights are lightened, that will make the valves open more quickly. That can lead to a slight bog, if they are lightened too much.
       
    • moper

      moper Well-Known Member

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      It's also a pretty good chance the step up springs are not perfect either. A vacuum gage taped to the windshield and a short test drive might help that determination. Carters and by virtue of genetics Edelbrocks are much more sensitive to airflow than Holleys. Holleys you can almost always just dump more fuel and it will work. The carter type designs take a little more finesse.
       
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      • lewtot184

        lewtot184 Well-Known Member

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        I think the AFB design is more sophisticated than the holley.
         
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        • rumblefish360

          rumblefish360 Well-Known Member

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          I like the AVS better, and yes, the TQ above that.
           
        • 451Mopar

          451Mopar Well-Known Member

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          This is my Carter/Edelbrock (CarterBrock) tuning kit:
          carterbrock1.jpg carterbrock2.jpg carterbrock3.jpg
           
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          • junkpile

            junkpile Well-Known Member

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            wow I had a lot of reading to do, I was out for a couple of days. I am looking into some of the things suggested. I will say the bog is only at 80% or true WOT other than that even with this cam it starts and runs flawlessly. Even drove this car to NY from GA with this set up, no running issues. but that bog will crop up when pulling in traffic or just trying to run it hard from a stop.