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Edelbrock 1406 carb problems

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  • Fuel System: Edelbrock 1406 carb problems

    I have the 1406 carb (600cfm,electric choke) on my Studebaker streetrod. It never idled correctly and drained in 3 or 4 days. I corrected a few problems yesterday and thought I would share what I found and what I did. First, I installed a Mr. Gasket pressure regulator I bought at Advance Auto and set it on 5.5 Lbss. I read where a lot of stock pumps have 10 to 13 lbs. pressure and I also have a electric pump in line to prime my carb after setting ,so this was easier than checking both pumps. Edelbrock wants 5.5 to 6 lbs at seats and I figure I could have been flooding motor. Second ,and most important, I found a built in vacumn leak. Its at front passenger side of carb in the electric choke and takes a 10-32 screw to plug it. After doing these 2 items, my air adjustment screws actually worked at they should and I was able to idle truck at 600 rpms and still put it in gear without killing motor, I think the small vacumn leak was my main problem . I do have another 1406 that has a plug in the same hole, but a new carb at advance auto still had the leak and needed the screw if bought. If you have one of these carbs , please check for the leak.
    Randy Wilkin
    1946 M5 Streetrod
    Hillsboro,Ohio 45133

  • #2
    I've had problems with a couple of the late model AFB's such as rough idle and stumbling. The tip on the vacuum leak is a good one, , I'll have to look for the missing screws. Bud

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    • #3
      Bud, if I didn't explain good enough, e-mail me and I will take a picture of where screw is . it only takes 1 screw and its at bottom of choke housing at front edge. I have another 1406 with a lead plug in the hole, but a new 1406 at advance was like mine, needed the 10-32 screw added.
      Randy Wilkin
      1946 M5 Streetrod
      Hillsboro,Ohio 45133

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      • #4
        Love to see the pictures on this when you can get them.

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        • #5
          Is the screw that you installed directly below the choke housing at the 5 o-clock position?

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          • #6
            If you installed one of the Lionel Stone aluminum intake reproductions,make sure to use a good composite gasket.
            The stock metal gaskets will not seal.
            The holes are off and you need to make it fit right by pushing it all the way over and enlarging or slotting the holes.
            Test for vacuum leaks by spraying carb cleaner all the way around the intake gasket using the spray can tube with the engine idling.
            If the RPM picks up at a spot , you have a vacuum leak there. some people use starter fluid but if you are a moron , do not try these tests.
            Don't do it inside!!
            Robert Kapteyn

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            • #7
              Picture of screw

              The threaded hole is to right of plastic cap on the round tube that the plunger in choke works . Am trying to attach picture of mine with 10-32 screw installed.
              Attached Files
              Randy Wilkin
              1946 M5 Streetrod
              Hillsboro,Ohio 45133

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              • #8
                That's interesting. I have a new 1406 in the garage that would not idle down either. It also has the same hole. It came on the 63GT I bought. I did not bother to try to figure out the problem. Since I hate those carbs on a Stude I simply swapped it out with my favorite, a "baby Holley".

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                • #9
                  My motor is a 355 sbc with a 327/350 horse cam,so it idleing at 600 rpm and staying running when dropped in gear is abig change from what it did in past. before it was 1000rpms and still studdered when put in gear and the air screws in front of carb seemed to make no difference. plugging that hole and installing a regulator completely changed the idle of the carb.
                  Randy Wilkin
                  1946 M5 Streetrod
                  Hillsboro,Ohio 45133

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                  • #10
                    Yep, the idle screws did not make any difference on mine either. Looks like you've stumbled onto something. Thanks !

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                    • #11
                      Would be interesting to call Edelbrock and inquire, just to satisfy curiosity if nothing else.
                      Pat Dilling
                      Olivehurst, CA
                      Custom '53 Starlight aka STU COOL


                      LS1 Engine Swap Journal: http://www.hotrodders.com/forum/jour...ournalid=33611

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                      • #12
                        Update, edelbrock claims the vacumn leak is their to cool the choke spring, claims plugging hole will burn up choke.
                        Randy Wilkin
                        1946 M5 Streetrod
                        Hillsboro,Ohio 45133

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                        • #13
                          I looked at the older AFB I have had on the 56J for decades, and that hole has a male nipple sticking out of it, which I attached the 56J's hot air tube to. That AFB was set up to use either the electric provision, or the hot air tube for the choke.

                          I have ran those AFBs on some Stude 289s over the years, but used the electric choke, and installed a rubber cap on the nipple. I am guessing the Edlebrock is electric choke only, but they left that hole there and forgot why. The Edlebrock could probably be set up to use a hot air tube by drilling that hole a little larger and installing a metal nipple.

                          For the Edlebrock rep to say the hole is there to provide air to cool the choke wire is kinda hard to understand since the coil has to stay hot in order for the choke to stay open.

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                          • #14
                            I am going to unhook my electric to choke, and back choke off ,just to see how truck runs. It idles so much better, and air screws adjust as they should,which they didn't before, so I want to see if mileage changes . I to don't understand why they say they need that leak for choke.
                            Randy Wilkin
                            1946 M5 Streetrod
                            Hillsboro,Ohio 45133

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                            • #15
                              Did you check to see if the electric choke is actually working. I discovered that I had a blown fuse on the circuit which operated the choke.

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