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Need advice setting up three 1 barrel carbs

Discussion in 'The Hokey Ass Message Board' started by 3onthetree, Mar 22, 2008.

  1. 3onthetree
    Joined: Feb 25, 2008
    Posts: 161

    3onthetree
    Member

    I have a 250 straight six chevy and will be running three rochester monojet carbs. (once I find an assortment of metering rods and jets) My plan is to run a progressive linkage for the end carbs.
    I was planning on all three running at idle or should I just run the center only at idle?
    Should I disable or somehow restrict the accelerator pumps on the end carbs?
    Should I remove the chokes from the end carbs as well?
    This is a daily driver and sees seasonal temps from the low 30's to upper 90's. Thanks for any advice.
     
  2. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    Screw the fuel screws on the end carbs right in, and back the idle screws off till the plates are closed. You may have to give them a slight open pressure to keep the plates from sticking shut. Fix the chokes open, or remove the plates. Remove the acc. pumps, and block the passages, on the end ones, too. Then you're ready to start playing with the jetting.
     
  3. JHhj0978
    Joined: Nov 30, 2007
    Posts: 158

    JHhj0978
    Member
    from Youngstown

    I would block off 2 of them and just run the motor on 1 carb...just have it for looks.
     
  4. dana barlow
    Joined: May 30, 2006
    Posts: 4,424

    dana barlow
    Member
    from Miami Fla.
    1. Y-blocks

    A progressive linkage is the right way to go,the center carb sets the idle ,but there dose need to be some small flow in the end carbs or it will bog as they open. The idle on 3 carbs to run OK ,runs a 100 or so RPM up from stock.:p
     

  5. HEATHEN
    Joined: Nov 22, 2005
    Posts: 7,591

    HEATHEN
    Member
    from SIDNEY, NY


    That'll be enough of that sass!
     
  6. 3onthetree
    Joined: Feb 25, 2008
    Posts: 161

    3onthetree
    Member

    Cool, I was looking at some three deuce V8 setups to use as guide that used the center carb only for idle, then I read somewhere the six would have better mixture distribution with all three carbs used for idle due to the long style intake. I guess I still adjust idle to get the highest vacuum reading and use one of those synchronizer things to be sure they're all drawing the same?
     
  7. VOETOM
    Joined: Aug 6, 2006
    Posts: 281

    VOETOM
    Member
    from MO

    My brother did just that on his 1970 Chevy six.It runs three Corvair one barrels. Check it out.
     

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  8. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    Running idle circuits on the end carbs might make it idle better, but at part throttle it makes it a bitch to get to run right with the end ones still spilling idle gas in while the center one is trying to do its job. Better to set the linkage so the engine has enough RPM when the two open that its above any stumble.
    Also, with a high cut-in speed, you can block off the vacuum metering system on the outers and jet them for WOT, which is the only time you use them anyway.
     
  9. zbuickman
    Joined: Dec 9, 2007
    Posts: 466

    zbuickman
    Member

    well put.... Ive fought this before. and its not fun. they work best as stated. let them pull open at above 3/4 throttle and youll be good:)
     
  10. 3onthetree
    Joined: Feb 25, 2008
    Posts: 161

    3onthetree
    Member

    I'm glad I asked. This seems like a simpler, easier to tune method. Thanks everyone.
     
  11. David Chandler
    Joined: Jan 27, 2007
    Posts: 1,101

    David Chandler
    Member

    I've never done this, but have given it some thought over time, as I have a 250 also. I would think it would be better if there was at least a minimum ammount of flow on the end carbs, only to keep the gas fresh in them if you are not opening them up much. I hope that you post what you do and how it works too.
     

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