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Technical Dual Edelbrock carbs

Discussion in 'The Hokey Ass Message Board' started by Dog01, Apr 13, 2014.


keep them or go back to a single carb

Poll closed Apr 23, 2014.
  1. keep

    26 vote(s)
  2. go back to single carb

    12 vote(s)
  3. 3 dueces

    9 vote(s)
  1. Dog01
    Joined: Aug 18, 2012
    Posts: 4

    from Ohio

    Can anyone tell me how to tune my dual carb setup. They are sitting on a 383 chevy with 64cc Edelbrock heads, flat top pistons, and a modest cam. I'm trying to figure out if I need to jet them down or what?:confused:
  2. 59Apachegail
    Joined: Apr 30, 2011
    Posts: 1,336

    from New York

    You might need to synch them up. I'm not a carb pro by any means. More info might help too. What size jets? Are they 2 or 4 bbl? Was it running good on one alone? Is your timing right? What is it doing that you think it is over jetted?
  3. Oh I'd say 3 carbs is going to give you more fits than 2.

    Carb tuning is a dance not a karate chop but you need to have the correct units for the application.
  4. Dog01
    Joined: Aug 18, 2012
    Posts: 4

    from Ohio

    They are the stock 500 cfm carbs. The car runs good but idles really rich. It also hates to start when its cold too. I was running a 650 CFM but had to jet it up and change the metering rods.

  5. Are you running a choke ? That helps with cold starts.

    Idle circuit controls your mixture at idle, that's the screws.

    It's not needed but if you are rookie a wide band sensor and gauge will advance you quickly.
  6. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    from florida

    I'm running two 600's on a 331 Ford and just took them out of the box and bolted them on. Plugs burn light tan, idles well, etc. Are you using progressive linkage ? What rpms are you idling at ?

    Edelbrocks are a little under tuned for smooth street use, so I can't see the jets being your problem.

  7. instead of guessing, just take it to a good chassis dyno operator, and sort it out.
  8. Great - doesn't help the guy figure out his problem.

    Give him a fish or teach him how to fish
  9. saltflats
    Joined: Aug 14, 2007
    Posts: 10,239

    from Missouri

    If they are of the AFB family make sure that your idle stop is not set up to far or you wont get any idle mixture control.
  10. buckd
    Joined: Nov 29, 2008
    Posts: 335


    Vacuum secondaries can be a problem with dual 4 bbls. But I hate Edelbrocks anyway so what do I know. BUCKD
  11. saltflats
    Joined: Aug 14, 2007
    Posts: 10,239

    from Missouri

    I guess before we try and fix it we should know what said set up is for.
  12. Nuff Said ! :D Guess how I voted.

    Attached Files:

  13. I prefer a single carb for the simple reason of tuning...since I don't have the proper tools for tuning double or triple carbs. :)
  14. 54MEB
    Joined: Nov 21, 2007
    Posts: 107


    I am running two 500s on my Son's truck with 350 and a mild cam.

    Our carbs are the ones specifically for the dual setup and were calibrated out of the box to get us close. We are also using the progressive linkage.

    It idles from both carbs so I set all four idle mixture screws at 3/4 turns to start and then adjusted them to achieve the highest idle and then setting the idle speed using the main idle screw.

    We drove it to the round up from Houston with no troubles and the plugs looked great when we got home.

    What specific problems are you having with them?

    Posted using the Full Custom H.A.M.B. App!
  15. missysdad1
    Joined: Dec 9, 2008
    Posts: 2,942


    Last edited: Apr 14, 2014
  16. Sure does!, especially if he's listening to, and help the knowledgeable dyno operator tune/adjust his carbs & ignition. If he lived down the street from me, I'd be happy to help him. It'd be cheaper and quicker going to a qualified chassis dyno/tuner, than chasing the 100's of opinions, he's gonna get hear. If you want to so it yourself, get a "How to Carter AFB Book, and an A/F meter and get to work. The fact that it is hard starting, would have me looking at the ignition first, more ignition problems are blamed on the carb/carbs than you can shake a stick at!
  17. Let me start by saying that I am not a big fan of the Eddy carbs. But I know of a lot of fellas that have had very good luck with them, even a guy that has held the yayhoo cup record and done it on a 2500 mile round trip.

    That said bigfoot has let us in on a very important aspect of your question. What is the problem with the 2x4 setup? It is running fat or stumbles or???????

    Give us information like CFM ratings, what the plugs look like, etc. Are you running them straight up or progressive?

    They no doubt can be tunned and are a very dependable carb for the most part.
  18. 46Ford
    Joined: Jul 7, 2006
    Posts: 80


    I ran 3x2's on my 46 for about 12 years and currently have a set on my T.

    If you set them up with the correct end carbs and run progressive linkage, they are great. If you try to go cheap and use regular carbs for the ends, they can be a bear to tune. It helps to keep the fuel pressure down to about 5 PSI, too.

    Three small rochester 2G's are only going to give you about 600 CFM or so. Perfect for an engine in the 327-350 CI range.

    BTW - Just responding to the poll, can't help you with the 2X4's.
  19. Only problem I see with a tri power setup is that if he can't tune two carbs he damned sure can't tune 3.
  20. 1971BB427
    Joined: Mar 6, 2010
    Posts: 5,791

    from Oregon

    I'm not a Edelbrock fan either, but I disagree with the vacuum secondary statement! Vacuum secondary carbs are a plus with dual carb setups, especially if you link the vacuum signals so they open together. Vacuum secondary carbs wont ever open before the engine calls for more, so they work much better in a dual carb setup than mechanical secondary carbs.
  21. Yup.
  22. models916
    Joined: Apr 19, 2012
    Posts: 380


    Lighter step up spring under the needles will allow the adjustment screws to have an affect on the idle A/F ratio. They are color coded and sold at Jegs and the like. Try one lighter and see if the screws have some adjustment.
  23. 46Ford
    Joined: Jul 7, 2006
    Posts: 80


    Can't argue with that!:D
  24. 30panel
    Joined: Sep 12, 2007
    Posts: 129


    Soon after I got my dual 650 AFB's going it started running rich. Problem was one float a had crack and flooded, replaced it running great ever since. Either progressive or direct. Did opt for a dyno A/F checked out fine.
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  25. 39 Ford
    Joined: Jan 22, 2006
    Posts: 1,558

    39 Ford

    He has the setup now he needs to get it adjusted no need to throw more money at it by changing it again. Paying a pro to set it up if he is willing to teach you is the most efficient way to do it. None of us sitting behind our computers have any idea what' s actually going on with it.
  26. Larry W
    Joined: Oct 12, 2009
    Posts: 729

    Larry W
    from kansas

    Edelbrock Tech line. go place to start if you stay with 2x4.

  27. That's the best part about tri power, all you have to tune is the primary. On a "correct" tri-power set-up the end carbs should not have idle circuits in them. You run off the center and bring in the ends as you see fit with progressive linkage. I've been running tri-power on all but one of my cars since 1966 and never had a problem as long as I used the right end carbs. That said, I think if he has a dual quad set-up he should tune it, rather than switching and spending more money.
    Last edited: Apr 14, 2014

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