5.9MAGNUM EXH MANIFOLDS

Early A-Body Discussions

  1. A/MP

    A/MP Well-Known Member

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    Putting together a 273/4bbl, 340 spec solid cam, high compression motor for a '65 Dart. Was thinking of using the magnum factory style exhaust manifolds. Good idea? Need the magnum bolt kit or just use the LA studs/bolts?
     
  2. Slantsix64

    Slantsix64 Well-Known Member

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    magnum passenger will work but you need to use bolts course thread. dont thnk the magnum bolt kit will work on passenger due to how tight the fit is you cant use the studs. Driverside use a 73 340 manifold 2.25 exit and 2 1/8 on the magnum passenger, worth it for sure.
     
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    • Bodyperson

      Bodyperson A little sketchy

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      I can not answer your question about how to fasten them. I can tell you fitment is an issue. Do a search. The subject has been beat to death. P/S and manual trans seems to be the biggest issue.
       
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      • Kern Dog

        Kern Dog Well-Known Member

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        True. The RH one fits great but the end studs have to be removed since each end of the Magnum manifold is much thicker than the LA versions and the stock end studs are not long enough.
        The LH side....
        IF you have manual steering and a column or floor type cable shifted automatic, the manifold might clear. The outlet points RIGHT at the clutch cross shaft in manual cars and at the cross shaft in '66 and later column shifted cars.
         
      • Treblig

        Treblig FABO Gold Member FABO Gold Member

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        There are two different magnum exhaust manifolds. Some have the smaller exhaust hole (exit) some have the larger (2 1/8") exit. Also the magnum manifolds (especially the large hole ones) have a much larger head port size causing some sealing problems. I'm not sure about the small exit hole manifolds but I believe that they also have the larger head to manifold ports. On an early A you're probably going to need a late 60s 340 driver's side manifold because it fits easier as opposed to the 70s 340 driver's manifold (manual steering only?). The large hole 96/97/98 Jeep Grand Cherokee passenger's manifold works best on the right side. You might have to grind off the casting numbers (pass side) and some raised portions of the Jeep manifold to clear the inner fender. I swapped to later small block heads to get the larger head exhaust port size to match the magnum (large hole) manifold. You could probably do the same as long as you stayed with the smaller valves for bore clearance and everything else is compatible?
         
        Last edited: Oct 14, 2019
      • pishta

        pishta I know I'm right....

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        'beat to death' and nary a pic to show us that is doesn't work. Anyone got a pic of the interference point?
         
      • Treblig

        Treblig FABO Gold Member FABO Gold Member

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        Pishta, what exactly do you mean by "nary a pic to show us that is doesn't work"? You're asking for pics of what? "What" doesn't work??? What "interference"?
         
      • RustyRatRod

        RustyRatRod 30 Degrees Outta Whack

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        He's askin for proof man. Pictures that the Magnum manifolds won't work on the driver's side. They'll work on the 67 and up cars, but as of yet nobody has pictures of trying to install them in an early car. By beat to death he means people have asked and asked and asked. No pictures yet.
         
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        • pishta

          pishta I know I'm right....

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          What Rusty said.....I've heard it, just have not seen it. If my 273 was in the 65 I'd prove it to my self, but the 'ol slants in it now.
           
        • ragtopfury

          ragtopfury Well-Known Member

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          Put them on the 408 in Jake's 65 B'cuda. It can work. I'll find the pics laterm this evening.
           
        • RustyRatRod

          RustyRatRod 30 Degrees Outta Whack

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          Yeah see, I got it and I ain't even that bright. lol
           
        • ragtopfury

          ragtopfury Well-Known Member

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          Starting at page 7 post #172 in this thread... may be more after 172, but I don't have time to look right now. This was on the 318 initially. When he upgraded to the 408 with aluminum heads a couple years later, he gained more room.

          The tear-down of Jake's 65 begins....

          So we have the body where we want it ready for my paint man. Decided to swap the manifolds out for the 5.2/5.9 Dakota/Dango logs. Minor issue. I knew the collar at the steering shaft needed to be trimmed a bit, and knew there might be a little grinding to do on the edge of the manifold to clear the shaft..... But The right side is dead against the inner fender - need to grind the pentastar and casting numbers off the manifold to clear it, but the left side is worse - it is dead against the steering colum shaft. So much so that the front of the manifold is pulled away from the head because the rear of it is pushed in from hitting the shaft. I think I will take them to a machine shop and have 1/16th of an inch milled off the mounting surface of both manifolds. I know it will give me what I need on the right side, and am hoping between the 1/16th and grinding the casting numbers off,along with an 1/8th inch shim under the motor mount, I'll get just enough to let the left side clear the steering shaft. And yes that is one orange plug boot on #7 - melted the black one off with the old manifold...lol

          manifold right.jpg manifold left.jpg
           
        • A/MP

          A/MP Well-Known Member

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          These 2 pics answer the Q completely. Thank you for this info.
           
        • Treblig

          Treblig FABO Gold Member FABO Gold Member

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          I would ask......are these the large hole manifolds or the small hole manifolds. Makes a big difference when it comes to clearance??
           
        • pishta

          pishta I know I'm right....

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          There you go, now I see where you have to attend with the clearance tools.

          I angle milled some 383 Hipo logs to clear the steering shaft on my 451 install and overlooked the bolt angles changing slightly. I fixed it by bending the 3 studs down a few degrees so they would fit in the manifold holes! Ghetto but it worked. Fit great!
          logs.jpg
           
          Last edited: Oct 14, 2019
        • Krazymofugger

          Krazymofugger Active Member

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          Magnum manifolds are on my 64 valiant wagon. They are off a 94 dodge van that the 360 came out of thats in my car. I have schumaker urethane conversion mounts. I had the manifolds machined on the mating surface . The thickness of the gaskets is all they took off. I ground off all the casting numbers so i couldn't tell you what they were its been several years ago when i did this. I also had to change the steering joint to a universal one i picked up on ebay. this set up has been ENGINE 10.jpg ENGINE 9.jpg ENGINE 7.jpg ENGINE 3.jpg my daily driver for about 8 years now. ENGINE 1.jpg ENGINE 2.jpg ENGINE 5.jpg ENGINE 6.jpg ENGINE 10.jpg ENGINE 9.jpg

          ENGINE 8.jpg

          ENGINE 4.jpg
           
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          • pishta

            pishta I know I'm right....

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            Damn, like it was made for it bro! Thanks for the legit pics! Motorhomes didnt even run exhaust gaskets...wonder how these would seal with only ultra copper? Did that U-joint slide right onto the stock 'pin delete' steering shaft? That's slick.
             
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            • YY1

              YY1 Well-Known Member

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              What later small block heads have larger exhaust ports?

              magnum?
               
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              • Treblig

                Treblig FABO Gold Member FABO Gold Member

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                302s (non magnum)
                 
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                • YY1

                  YY1 Well-Known Member

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                  I did not realize the 302 had larger ports.
                   
                • Treblig

                  Treblig FABO Gold Member FABO Gold Member

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                  YEP!!
                   
                • Krazymofugger

                  Krazymofugger Active Member

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                  If I'm remembering correctly i had to open the the steering joint very little. I used sand paper on a dremel tool. I did drill the steering joint and used the factory pin. It was too long so I cut off the extra. I wanted the have the option to put it back to stock if I wanted to.
                   
                • Treblig

                  Treblig FABO Gold Member FABO Gold Member

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                  Now, just for the record.....are those the smaller hole manifolds, at least that's what they look like??? If I knew the casting number I would know for sure. If they are the large hole manifolds you have a great combination there!!!
                   
                • Krazymofugger

                  Krazymofugger Active Member

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                  I know for sure the manifolds came out of the 94 ram van that the 360 came out of. There are no numbers on them anymore but probably the smaller hole manifolds. I have 2 1/4 duel exhaust from front to back with flowmaster style (thrush)mufflers.
                   
                • YY1

                  YY1 Well-Known Member

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                  IIRC the "large" outlet parts are 92 only.

                  At least on Dakotas.
                   
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