2bbl Intake... To Make or To Find?

Slant 6 Engines

  1. jos51700

    jos51700 Green Bearing thread connoisseur

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    I remember seeing a half dozen super 6 cars in the KC pick n pull in the late 90's.
    Of course, at the time there were dozens of Darts and the occasional gen ii Charger or Challenger. Rallye wheels aren't hard to find, and about 1 out of fifty was a stick shift car. I was even aware of the concept of pulling parts in the yard and selling them online, but I thought, meh, I'll do that later.

    And I just figured it would always be like that. What a dumbass.

    I'm glad to see a member willing to help another member out! I have to ask though... if you're going to go welding and machining on a slant 6 manifold, why not add at least some nitrous nozzles and maybe some EFI bungs?
     
  2. ch1ll

    ch1ll FABO Gold Member FABO Gold Member

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    "I did not know that"

    same size port cross section size AND runner length?
     
  3. RustyRatRod

    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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    Offenhauser improved a little on the port length difference. The factory intake though, gets a bad rap for port runner differences. Much moreso than it deserves. If you do some reading, you'll discover that the slant 6 has about the best fuel distribution of any inline 6 engine if its day.

    That's one of the things that Chrysler was proud of and yet, it's one thing that most everyone says is bad, and incorrectly so. The intakes are deceiving in that the runners are not the lengths that they appear to be from the outside.

    A quick inspection will reveal that they are a good bit closer to equal length than the outside of the manifold lets on, because the dividers inside of the manifold are not where the outside of the manifold make you think they are.

    Offenhauser improved on this even more. They also left the runners as long as possible while making them "a little" more equal than the factory intakes. That's one reason I like the Offenhauser better, now that I'm more familiar with it and have had one a while. They have more runner volume, while the Clifford had more plenum volume.

    I think for some reason, the big plenum theory is backwards on inline engines. Normally, on a V8 a large plenum positively affects low speed torque, while a smaller plenum positively affects high speed torque. This is the big reason older single plane intakes, like the Street Dominator, for instance, do not appear soft on the bottom end.

    I think it's the opposite for inline engines, for some reason. It sure is on mine, at least. It's not soft on the bottom end one iota. With the 2.93 gear, you could "tell" it needed more gear "RIGHT" when you engaged the clutch, but changing to the 3.90 gear, I can tell beyond a shadow of a doubt, that if I had swapped to just a 3.21 that I would have gotten rid of every bit of that. It's simply no longer there "AT ALL". It pulls like a whore in church now from off idle until 6200......that's as far as I've gone with it and it was still pulling. That's as far as I plan on going with it and that was actually an accident. I got carried away. lol That long 4.125" arm is really moving at that RPM. My intended redline was about 5500-5800.

    Maybe "one day" I can build something more exotic that can be durable enough to really rev, but for now, I'm limited to stock style bottom ends.

    All this of course, is just one idiot's opinion.
     
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    • kesteb

      kesteb Well-Known Member

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      In my experience and testing, there is no difference between a SuperSix and a Offy power wise. The only difference that I can tell is the Offy weighs less and has a bigger hole for a carburetor. The short runner Clifford on the other hand is considerably better then either.
       
    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      Better at what?
       
    • kesteb

      kesteb Well-Known Member

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      Everything.
       
    • petty437

      petty437 FABO Gold Member FABO Gold Member

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      Well at least zmarty27 is also in TX! LOL
       
    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      I'd like to see proof including dyno and drag strip numbers. No "ONE" intake is better at "EVERYTHING". Ain't happenin.
       
    • Tooljunkie

      Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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      Not really relevant, i made an adapter to put a 2bbl on my 51 flathead.crude as crude can be. It worked swell. I even managed to get automatic choke to work. That was a 318 carb on a 218 engine. If it wasnt for massive blowby i would still be running it. 360/727 now. 3x the power, but you hardly notice…
       
    • zmarty27

      zmarty27 Active Member

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      To be honest, I am surprised I’m digging this deep into this project. EFI and Nitrous is a whole new realm for me. Next task for me is probably the AC. That’s another thread for another time, though. Jonn6464 really did come through for me, didn’t he?
       
    • jos51700

      jos51700 Green Bearing thread connoisseur

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      Yes he did!
       
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      • slantsixdan

        slantsixdan =..=

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        • Thanks! Thanks! x 1
        • Killer6

          Killer6 Well-Known Member

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          I've asked for that before when He made this assertion, & more specifically, if anyone else had this result/opinion. Crickets. I'm not saying it's incorrect, as many are surprised by some single-plane V-8 intake low-end torque/high-end superiority over plain-jane DP intakes. But if I make a 1st hand knowledge statement, I'll give numbers and details to back it up,........
           
        • RustyRatRod

          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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          I'm not saying he's wrong, either. Clearly, the Clifford is different from the traditional long runners the stock manifold has. All I know is, my slant 6 runs great with the Offy, that's what I HAVE so that's what I'm using. lol
           
        • Slantsix64

          Slantsix64 Well-Known Member

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          I heard clifford intakes make more top end, than the offenhauser which is focused on that low end mid range , honestly low end is where it’s at with these slant sixes.
           
        • RustyRatRod

          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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          I agree. The Clifford HyperPak copy was really something. They are badass, if you can find one. But the one they sell now is more focused on really hot street and race applications, IMO.

          But as we all say, it's all dependent on the tune. Tune what you "HAVE" to run well and ti'll be hard to improve on it. Whatever it is.
           
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          • bcschief

            bcschief Well-Known Member

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            I had been looking for that article I remember it being in the Slantsix Quarterly ( pre internet for you young ones )
             
          • slantsixdan

            slantsixdan =..=

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            It was in the Slant-6 News (not the Quarterly).
             
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            • kesteb

              kesteb Well-Known Member

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              I have no hard numbers from a time slip. When i did the a/b swap, i was experiencing carb issues. My butt-o-meter was that the clifford was superior in all respects from the offy. I attribute this to a larger plenum, and tapered runners.

              The offy is just a copy of the 1v intake from 1959 with a flange for a carter wcfb carburator. But then i have noticed different appearences with the offy over the years. Which makes me wonder who is casting the clifford manifold.
               
            • pishta

              pishta I know I'm right....

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              $170 for the cable kickdown setup? Go russle up a stock lever 2bbl kickdown for that. keep it real. I got 3 1bbl iron intakes kicking around, not sure what Im going to do with them. Probably EFI bung them and sell 'em with a TB. No value otherwise unless someone here needs one cheap.
               
            • dirty white boy

              dirty white boy 50 yr old Juvenal delinquent

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              ...after you proved the injectors do better in the head and showed us how to do it??? how much to put the bungs in my head for me????
               
            • volaredon

              volaredon Well-Known Member

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              I've been told that you can get the throttle kickdown cable off of a Dakota or grand Cherokee from the boneyard and the bracket off the same engine and it not being hard at all to adapt it to a super six setup. Haven't tried it yet myself bit am gonna once I swap out engines in my truck,my new one is a super six where the original still in place is a 1 bbl
               
            • pishta

              pishta I know I'm right....

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              you got a head to send me? .......$$$ Bunging is cheap: 3/4 hole saw and some 3/4 thick wall AL tube, drill out the tube with a injector step drill and epoxy them in at preferred angle. Works for head and old intakes, especially the AL ones. The epoxy only seals the bung, all the injector support is done by the bolt on rail.
               
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              • newmexguy

                newmexguy Well-Known Member

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                I've only seen ONE E body Challenger / Barracuda in a yard, ever, and it was a rotten mess, that had also been burned. Sounds like it was one heck of a pull a part, back then!!
                 
              • /sixchall

                /sixchall Well-Known Member

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                I do have a 70 Challenger with the factory Slant6, not the numbers matching engine, but one I bought from a Dodge dealership. I have modified the engine with the Super Six set up and am happy with the conversion.
                 
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