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6x2 progressive vs. straight linkage

Discussion in 'The Hokey Ass Message Board' started by lucky23, Aug 13, 2012.

  1. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Finishing up with the install of my 6x2 Edelbrock/Holley 94 set up. Trying to get opinions of what people have experienced. Was gonna run straight linkage set-up but thinking maybe a slight progressive set-up. No sure what to do. Been told straight linkage seems to run better. Thoughts?


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  2. GassersGarage
    Joined: Jul 1, 2007
    Posts: 4,727

    GassersGarage
    Member

    I would imagine trying to set up straight linkage using a uni-sync or some such device would be a pain. Adjusting each individual carb so they're pulling the same amount of air. I know on bikes, I use to have a set of 4 vacuum gauges to set the carbs, going back and forth so each carb was pulling the same vacuum. I ran progressive on my tri-power, but the cool factor with 6 carbs would be great.
     
  3. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Was debating on ordering straight linkage from Vintage Speed or Eelco low profile 6x2 linkage. What to do?


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  4. Don't know what motor or carbs you're running, but straight linkage will dump one hell of a lot of fuel! Get ahold of Dick at http://www.dickshotrodcarbs.com/ he can dial you in.-MIKE;)

    He did a hell of a job on my setup, and is a wealth of knowledge, too.

    [​IMG]
     

  5. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 1,379

    Jmountainjr
    ALLIANCE MEMBER

    You didn't say what engine and didn't say how you built the carbs - do the carbs all have working idle circuits?
     
  6. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Engine is a 327 with mild cam on it, Carbs are Holley 94's


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  7. The question is what are you running a short case on?

    Opening 6 dueces all at once is a lot of air for the average engine. I would probably run them progressive if it were me have your out board carbs start opening @ about 40% throttle and have them all all in by WOT.

    Then next question is are the outboard carbs actually out board carbs? Do they have the idle circuits blocked and do the throttle blades close all the way and block the throttle bores. If not then you have no other choice but to run them straight and not progressive.

    This brings us back to the original question, do you have enough engine to handle all that air all at once.

    If it is just for looks which is the case on most 6x2 setups then the out board carbs should be dummies, remove the throttle blades, run dummy fuel lines to them and block them off between the base plate and the intake.

    Sh one more question to be asked about the setup, do they share a common plenum as in is it a log setup or are they seperate plenums for each carb. if they donot share a common plenum (most do but some don't) then you will have to run them straight and no progressive.
     
  8. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    The outer Carbs do close all the way so the idel circuits are blocked off. it is a log manifold so 3 carbs share a common plenum.
     
  9. carbking
    Joined: Dec 20, 2008
    Posts: 3,196

    carbking
    Member

    Assuming the manifold is capable of it (see the "beaner's" post above); and you are an absolute glutton for punishment, but want the very best ultimate performance:

    Dummy the two CENTERS; and run solid linkage on the four ends.

    Good luck with your project.

    EDIT: Disregard this post, your post that the idle circuits were blocked came while I was typing the above.

    Jon.
     
  10. The log is the plenum, if you are running a V-8 then you should actually have a log for each bank with balance tubes between them if they are old enough to not have balance tubes you should modify them to have banace tubes it makes them a lot easier to tune.

    If in fact your outboard carbs are idle circuite delete then you should by all means run progressive. Here is something that you should do as well, close the throttle blades all the way and hold them up and look through them, you should have no light showing around the throttle blades.

    I am not doubting you here just giving you some things to look for before they have a chance to bite you real hard. I would like to hear from you that you got it going and it is as smooth as silk.
     
  11. Littleman
    Joined: Aug 25, 2004
    Posts: 2,619

    Littleman
    Alliance Member
    from OHIO, USA

    I have run my 10.34 compression 327 the original engine I had in my Model A Pickup, stock fueler heads, Offy six-two intake, Isky Hyd. cam w/ 221 duration @ .050....464 lift,This engine is the definition of mild..94 carbs.... Run it alway's w/ straight linkage never tried progressive, power valves blocked in all the carbs and was able to get it to run like a banshee...But you have to want to do the time and work...I have alway's thought progressive is for a StreetRod and Straight is for a HotRod...ha ha...But really you can get either to work for you...you just need to want it.......Progress on, Littleman

    I will add....their can be allot of swearing involved !
     
  12. This is my setup which I've used on my 371' Olds since 06'. It's progressive linkage which I chose just because it's easier to tune. No power valves and the four corner carbs also have the idle circuits closed off so all they do is dump when you mash the pedal. Notice the cross bar with the three arms is splined to avoid any slipping out of adjustment. Also the link between the bell crank and the middle arm has a left hand thread on one end so it works like a turnbuckle. I can adjust the idle on both center carbs at the same time rather than going back and forth trying to get them the same. Hope this helps.
     

    Attached Files:

  13. Littleman
    Joined: Aug 25, 2004
    Posts: 2,619

    Littleman
    Alliance Member
    from OHIO, USA

    Your results will vary....Good looking setup 550Coupe.......Littleman

    <iframe width="640" height="360" src="http://www.youtube.com/embed/R2Y-bGhsFQU?feature=player_detailpage" frameborder="0" allowfullscreen></iframe>
     
  14. pitman
    Joined: May 14, 2006
    Posts: 5,151

    pitman

    I liked progressive for street use. Off idle response on a 327 SBC was fine, even if over carb-ed for the engine's demands.
     

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