Need help tuning AED carb

Discussion in 'Fuel and Air Systems' started by duster360, Jun 28, 2018.

  1. duster360

    duster360 Well-Known Member

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    I just got my car running again and the AED 650DP carb is way too rich. I ran it for a short time last summer and it was way rich. Put my Holley 4777 DP back on and it was way better. I have just now got the car running again, sold the Holley over the winter and have reinstalled the AED and a wideband. At idle it is around 12.5 and cruise is 11.4, sometimes less.
     
  2. duster360

    duster360 Well-Known Member

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    Combo is 67 dart
    340 ci
    Dynoed 400hp
    Timing is 20* at idle
    34* total
    4 speed
    3.55 gear
     
    Last edited: Jun 28, 2018
  3. Dana

    Dana FABO Gold Member FABO Gold Member

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    What size idle air bleeds? what is your primary jetting?
     
  4. mderoy340

    mderoy340 Well-Known Member

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    Post up all the carb info. IAB, MAB, IFR, PVRC, etc
     
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    • duster360

      duster360 Well-Known Member

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      I will post a picture of the spec card in a minute.
       
    • duster360

      duster360 Well-Known Member

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    • duster360

      duster360 Well-Known Member

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      Picture

      6FB5E793-490C-495A-8E5C-FBA08919C887.jpeg
       
    • mderoy340

      mderoy340 Well-Known Member

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      The pri sec jets look good. Go down to 64 primary and see if that helps cruise AFR. Cruise comes in around 2200 rpm, you should be able to see the transition on the AFR gauge. Anything below 2200 you are running on the idle circuit. Set idle mixture for best idle and transition off idle. Do not try and run 14.5 at idle, carb motors need the extra air fuel at low rpm.
      These new carb metering blocks have to much emulsion IMO. You probably have 4 or 5 holes which causes fuel flow early. I only run 2 .028 emulsion. Try the 64 primary and see if that helps cruise.
       
    • yellow rose

      yellow rose Doctor of Thinkology.

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      What is the idle feed restriction? Should be ~.036-.039ish. I don't see that on the card. You can open the idle air bleed up a bit and clean up the bottom some.

      Also, you need to think about adding T-slot restricters. It's easy to do and cheap and will really clean up the bottom and cruise numbers.
       
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      • duster360

        duster360 Well-Known Member

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        I would like to get the idle in the 13's range. The low 11's at cruise are what really concerns me. It gets worse when I tip into the throttle.
         
      • duster360

        duster360 Well-Known Member

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        I will see what I can find out about the IFR. I have been trying to find some replacement Idle air bleeds for this carb but don't cant find them.
         
      • duster360

        duster360 Well-Known Member

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        That 4777 ran great, should have just kept it. What could be that much different between
        these 2 carbs that the AED just dumps so much fuel. I know I will get this sorted out and have a great carb. Just a little frustrated.
         
      • duster360

        duster360 Well-Known Member

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        This is the type IAB it has.

        7C633147-2F06-4690-92DE-E14B3A7558F9.jpeg
         
      • mderoy340

        mderoy340 Well-Known Member

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        Those idle air bleeds with the hex are drilled brass set screws. McMaster Carr sells them in packs of 50. The main air bleed is not changeable. Put the 64s in up front and report back. On a 650 a .033-.035 IFR is all I've ever needed on a 340. Take a pic of the emulsion holes on the metering block when you change the primary jet. Adjust the idle to 13:1 with the motor fully warmed up. How many turns out are the idle screws? Is it 4 corner?
         
      • 360duster

        360duster Well-Known Member

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        when i used a carb (750 AED HP with Aluminium main body - now EFI) i had the same situation. I could only get it to idle good with the IAB´s completely removed......after getting some blanks for the IFR´s i drilled some smaller ones (0.031" if i remember correctly, still written on the inner fender ;-)) it was MUCH better....could open up the mixture screws where they should be and put some IAB´s back in. It was a tad rich idling / cruising, could have gone 0.029" or so....did not more tuning because swap to Sniper EFI. Now it´s idling at 14.5 AFR without any trouble.

        Test some smaller idle feed restrictors

        Michael
         
      • duster360

        duster360 Well-Known Member

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      • mderoy340

        mderoy340 Well-Known Member

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        I would use .026 emulsion in #2 and #4 counting top down and plug the rest.
         
      • duster360

        duster360 Well-Known Member

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        Metering block

        E08D5C2E-ED53-4C53-9CA4-7666E29758CD.jpeg

        2380188B-B915-45BF-AE6E-FBD241E1763D.jpeg
         
      • duster360

        duster360 Well-Known Member

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        Changing jets now. Should I use the 4.5 power valve that cane with it or use a 6.5 or larger. Cam pulls a good 12” of vacuum. Normally I would go with a lot larger power valve but under the circumstances I am not sure
         
      • mderoy340

        mderoy340 Well-Known Member

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        Stick a 6.5 in if you have one. You need to get cruise fixed first. What size is the IFR? What size is the PVCR holes?
         
      • duster360

        duster360 Well-Known Member

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        I did go with the 6.5 PV. I don't have any pin gauges to check the sizes of the IFR and PVCR holes. I went to the 64 jets. I am having some surging at light throttle getting up to speed. One thing I should mention is my timing was way high. Not sure how I managed that, but it is back where it needs to be now. 20* at idle and 34* total. Idles around 850-900 rpm. I readjusted the 4 corner idle screws and the AFR gauge readings are slightly better. I am slightly over 13.0 at idle, cruise is in the low 12's now. Not sure if I need to go back up to 66 jets or put in a 7.5 PV to get rid of the surging. I have a new 7.5 PV in stock. I also noticed that when I gave it heavy throttle that it would go full lean just for a second and then drop back in the 13 range.

        I called AED tech line today to pick their minds and get more detailed specs on the air bleeds, but they are racing at a PDR event. Just my luck.
         
        Last edited: Jun 29, 2018
      • duster360

        duster360 Well-Known Member

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        OK. Did some more tuning today. The 4 corner idle on this carb is super sensitive, move it a little and it changes a lot. I now have it idling in the high 13's. I am comfortable with that. I now need to concentrate on cruise situations. I am cruising low 12's. That is around 55 mph and around 2400 rpm. Tach is inop at the moment, just guessing from memory.
         
      • yellow rose

        yellow rose Doctor of Thinkology.

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        How much vacuum do you have at a cruise? That's what you need to know to pick your power valve opening. Idle vacuum doesn't mean anything when selecting PV opening.

        That will probably clean up the lean surge. Also, don't fall in love with an AF number. Make the car run the best and check your plugs. Then you can use the AF gauge.
         
      • mderoy340

        mderoy340 Well-Known Member

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        At 55 mph you are cruising on the primary jet. You will need to go back to 66 to get rid of the surge. Read the plugs after you go for an extended cruise as YR said and see where you are at. The AFR is a tool not gospel. Installing smaller main air bleeds will delay primary fuel flow but the MAB holes will need to be tapped for that to happen.

        I also noticed that when I gave it heavy throttle that it would go full lean just for a second and then drop back in the 13 range. Make sure you have instant pump shot when moving the throttle. You went lean getting into the throttle and recovered to 13 so I'll bet pump shot adjustment is off.
        Hopefully AED will let you know the other specs.
         
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        • duster360

          duster360 Well-Known Member

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          Been doing some more tuning. I put the 66's back in and the surging went away.
          Has just a little hesitation when I floor it quickly. Almost like a slight pause and then the afterburners kick in.


          Idling after a 30 minute drive.




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