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2x4 or 3x2 for best drivability on a mild engine?

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  • 2x4 or 3x2 for best drivability on a mild engine?

    Guys, what is your real-world experience with old school low rise multi-carb intakes for street driving? I'm looking at swapping on either an old Weiand or Offy 2x4 with a pair of 500 Edelbrocks, or an Edelbrock F380 with triple Rochester 2G carbs on the stock 390 in my 66 TBird.

    I realize that neither of these will be optimum for performance, mainly I'm trying to add some visual appeal under the hood, and lose the weight of the stock cast iron intake while I'm at it. The TBird has a very low hood line, so it has to be an old school low rise intake. The guy who has the 3x2 setup for sale claims that he was able to get 17 mpg out of it in his early 60s Galaxie on a long highway trip, which is pretty decent for an FE engine.

    Am I correct in thinking that the 3x2 will probably be better suited and more responsive on my stock engine in a heavy car with 3.00 gears? The only downside I can see to the 3x2 with the 2G carbs is that they will look a bit lost on top of that big engine, whereas the Edelbrock 4-bbl carbs will have enough size to make a better visual impression. Of course choosing the right air cleaners will make a difference to how it turns out as well, I won't be able to go with anything that is very tall.

    Suggestions, opinions, your experiences?


    cheers
    Ed
    Ed Nicholson - Caledon Ontario - a bit NW of Toronto
    07 Mustang GT with some stuff
    88 T-Bird Turbo Coupe 5-speed

  • #2
    I'd go 2x4, it's hard enough syncing two carbs none the less syncing 3 carbs......

    Also two 500's??, I'd be looking more at two 650's if it was me....... Remember just because you add another carb doesn't mean that you double the CFM going into the motor, each carb will only flow the CFM that it is rated at, though the pressure drop across the carbs will be lower with two carbs than just running a single carb.......

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    • #3
      I don't think the low rise is a 2-4-6-8 barrel sort of a deal..
      More like the primaries will be on all the time.. I have been wrong before..
      With 3X2's you can set when the outer carbs come in..they generally have no idle circuits .. Nor chokes..
      The outer carbs have linkages on the right side and the primary has linkages on both sides...
      Either one, properly set up will give you sweet seat of the pants feel..
      You are on the right track with 2-500 cfm 4 barrels.. That is what the factories used in the early 60's, late 50's 2X4 set-ups of all makes...

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      • #4
        TC, keep in mind that this is a 4,200 lb. car with an auto box and 3.00 gears ... it would be hard pressed to see the high side of 4000 rpm. So 500 cfm should do the trick I believe. Edelbrock has some of their 500 AVS carbs that are specifically calibrated for a 2x4 on a mild larger displacement engine.

        Bob, the 3x2 system that I am looking at does have the outer carbs as you describe. The primary is a manual choke, I would have to look at what it might take to convert it to electric ... a hand choke just doesn't seem right on a classy car like a Thunderbird that has power everything else.


        cheers
        Ed
        Ed Nicholson - Caledon Ontario - a bit NW of Toronto
        07 Mustang GT with some stuff
        88 T-Bird Turbo Coupe 5-speed

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        • #5
          Myself I would go with the 2 X 3... it is a PITA to dial them in but
          they give you a better drivable car with the short intake... if it was
          a tall tunnel ram I would go with the 2 X 4.... neither one will be
          a real torque maker(short intake)

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          • #6
            Tbirds look nice with the hood closed...put an aluminum intake with a single 4bbl on it, and have fun driving.
            My fabulous web page

            "If it don't go, chrome it!" --Stroker McGurk

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            • #7
              Early T-birds had 406's with 2X4's?
              I remember seeing one, but is it factory?

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              • #8
                Three deuces.
                Drag Week 2006 & 2012 - Winner Street Race Big Block Naturally Aspirated - R/U 2007 Broke DW '05 and Drag Weekend '15 Coincidence?

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                • #9
                  Originally posted by Deaf Bob View Post
                  Early T-birds had 406's with 2X4's?
                  I remember seeing one, but is it factory?
                  Don't think that the 406 ever found its way in to the Birds, just the full size Fords and Mercs. They did have 3x2s, and the same style of intake (but with level carb pads) was an option on 63 (and maybe 62 as well) 390 T-Birds.


                  cheers
                  Ed
                  Ed Nicholson - Caledon Ontario - a bit NW of Toronto
                  07 Mustang GT with some stuff
                  88 T-Bird Turbo Coupe 5-speed

                  Comment


                  • #10
                    Originally posted by squirrel View Post
                    Tbirds look nice with the hood closed...put an aluminum intake with a single 4bbl on it, and have fun driving.
                    That's probably the most common sense answer that I will get ... what the heck are you doing on this forum? LOL

                    Definitely food for thought.


                    thx,
                    Ed
                    Ed Nicholson - Caledon Ontario - a bit NW of Toronto
                    07 Mustang GT with some stuff
                    88 T-Bird Turbo Coupe 5-speed

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                    • #11
                      Drivability and lack of maintenance should never be uttered in the same sentence with multiple carburetors.

                      That said - it's been done - but it won't be easy, cheap, or quick to make it right, and depending on what carbs you run, keep it running right.

                      How much do you want to spend?
                      how much do you want to tinker?
                      how cool are multiple carbs?
                      what's wrong with it now?
                      There's always something new to learn.

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                      • #12
                        I would go with the 6 pack. Its all in the linkage. You run the center two barrel for regular driving when you arent getting stupid, then half throttle to the floor the front and back open. Just need half the throw on the bell crank so from half to full the outside carbs go wide open.

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                        • #13
                          I like the looks of 2x3 since it is different. I will let you know if its a pain to tune shortly......sure does look nice though. I built this 327 SBC for my dad's 37 Chevy.


                          Nick Smithberg
                          www.smithbergracing.com

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                          • #14
                            YO - Ed - I have a 283 in a 28 Model A w/4 spd and 2.73 geared rear end. I am currently running a Weiand 2x4 intake manifold w/ 2 - 600CFM Edelbrock vacuum secondary carbs. The motor is happy with the dual quads because I closed the mixture screws all the way in and backed off the idle speed screw on the front four barrel. This way the motor runs on the back carb only and the front carb doesn't come in till half throttle(progressive linkage). Makes a nice roar when all 8 open up and the real kicker is that running with the hood off it looks good.
                            Any other questions I would be happy to answer them.

                            Have fun - Jerry
                            Last edited by 28coupe; October 17, 2012, 06:24 PM.

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                            • #15
                              Ed: recommend you put your question to the fellows over at Jay Brown's FE Power Forums.

                              http://fepower.net/simplemachinesforum/
                              Last edited by mlcraven; October 17, 2012, 06:35 PM.
                              Michael from Hampton Roads

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