A500/A518 to Gen-III

New Hemi Engine Swaps

  1. Cazbah362

    Cazbah362 Well-Known Member

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    Doing my research on my Gen-III to 71 Demon swap. At this point, I plan on using an A500, however finding details on if there is a swap type flex-plate needed. Any insights would be of great assistance.

    At this point, I plan on using the US Car Tool cross member, and may need to trim the tunnel. I seen a few OD Switch's or setting up to vacuum (not sure on this part yet either).

    Thanks in advance
     
  2. DrEamer

    DrEamer Well-Known Member

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    • 1973Barracuda

      1973Barracuda Well-Known Member

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      You may want to look into adjustable NOS switches. That allows you to adjust shift point. At least one company offers a kit, but the shift point are fixed.
       
    • Cazbah362

      Cazbah362 Well-Known Member

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      drEAMER - Thanks, I figured someone had the answer:

      1973Barracuda - can you explain the NOS switch concept, or point me to one of the kits.
       
    • DrEamer

      DrEamer Well-Known Member

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    • 67Dart273

      67Dart273 Well-Known Member

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      The H series transmissions simply have a 3 wire connector to control OD and lockup. All you need are two switches, either manual toggles or a pair of vacuum / pressure switches (barometric) If you go to the "free manuals" thread there is/ was a russian site where you can download the ATSG transmission books

      Free service manuals

      Here

      Коробки передач | Интернет-магазин запчастей для автоматических коробок переключения передач
       
    • Cazbah362

      Cazbah362 Well-Known Member

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      Spaseeba!
      That Compushift is a bit out of my price range, but nice to know it is out there.
       
    • 1973Barracuda

      1973Barracuda Well-Known Member

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      When I was going to use a 518 behind my 6.1, I was setting up to use one of these-
      Search Results for Adjustable nos switch

      I didn’t want a set mph/pressure shift point. I wanted some flexibility.

      You can look online and see the kits with the set pressure switches. Just build one yourself with adjustable switches.

      Good luck.
       
    • Cazbah362

      Cazbah362 Well-Known Member

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      1973Barracuda - Thank you, after reading your post, I did a little research. I found this link here describing how to wire up the switch - very interesting.
       
    • DrEamer

      DrEamer Well-Known Member

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      • 1973Barracuda

        1973Barracuda Well-Known Member

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        Yep, that is the kit.
         
      • Cazbah362

        Cazbah362 Well-Known Member

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        Last question, convertor has the balance weight, assume I remove it? (Triangle piece of steel welded on)
         
      • 1973Barracuda

        1973Barracuda Well-Known Member

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        I believe that depends on your flex plate.
         
      • 75slant6

        75slant6 Well-Known Member

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        @TrailBeast did an a500 swap behind a 5.9 magnum and built his own kit using vacuum controlled, adjustable switches.
         
      • TrailBeast

        TrailBeast Slightly Twisted Member

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        The shifting kit that I built works just like the kit that is in the link above and uses governed pressure tapped into the governor pressure test port on the trans.
        The BIG and main difference between what I built and that kit above is that I used adjustable pressure switches so I can set the speeds I want the trans to shift at.
        That kit linked above uses pre set pressure switches, and is why you have to select the shift speeds you want when you order the kit.

        Example:
        I just changed wheels and tires so it changed my shift points, but I can adjust my switches to compensate for that.
        Those kits do not allow any changes because those switches are not adjustable.
        Mine are 35-75lbs adjustable and on the back of my intake so I can get to them easily to adjust.
        One for OD and one for lockup.

        SANY0007.JPG
         
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        • DrEamer

          DrEamer Well-Known Member

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          Just for general knowledge, the PACT kit does offer the adjustable switches for another $22 per switch. You have to click on the option links. That said, if you can put the kit together like TrailBeast, and save some money, that is great.
           
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          • TrailBeast

            TrailBeast Slightly Twisted Member

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            Ah, didn't see that.
             
          • 89on35s

            89on35s Inferno Red Duster FABO Gold Member

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            A-500 transmission OD and LU controls.

            Here's a link to what I did. Shows my mistakes along the way. It does include part numbers for some cheaper Honeywell adjustable switches I used. I used Trailbeast's work for my inspiration.

            Cley
             
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            • dartgarth

              dartgarth Well-Known Member

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              Just an FYI, I had was using manual switches and had rounded up pressure switches to use with my BB/A518 swap with Sniper injection, but then I saw the Comushift mini kit so I got that. It works really slick for something with a TPS. Another side note is that I was going to use the AC cut out feature on the sniper to turn the OD off instead of the vacuum switch normally used.

              Garth
               
            • Ronald C.

              Ronald C. FABO Gold Member FABO Gold Member

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              Guys, my Gen III 5.7 arrives next week. I had steered away from the 518 route and was staying with the 904 when I was going with a Magnum build. But, I’m curious now, anybody have an opinion on the performance of the A518 vs. 904 when behind a 5.7? Is there a noticeable power loss as a result of the OD? I had read, mind you on the Internet, the 518 would choke your HP and advised to “stay with the 727” . Mine won’t be a “daily” driver, but I do intend to drive it regularly. And honestly since I won’t be frequenting the track, I would forgo an 1/8th of a sec worth of HP for the flexibility of driving where/when/how I want.

              Any truth to this or do the benefits outweigh the mods and minor decrease in HP?

              Pics?
               
            • 1973Barracuda

              1973Barracuda Well-Known Member

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              I backed out of the 518 and went a41. But if you aren’t going to go to the track, and it’s a cruiser, I would suck up the “loss of HP”. I don’t think it is as bad as make it out to be, that said, there is a loss, but you average dude won’t miss it I think. I would go with the OD if you plan on doing freeway miles.
               
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              • Ronald C.

                Ronald C. FABO Gold Member FABO Gold Member

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                I think I am. For planning purposes anyway. Maaaaybe I change my mind when it come time to stab it but, if it’s truly only a couple HP, i.e. not 20 or 30, I think I may get down the road and eventually regret not doing it.....
                 
              • Ronald C.

                Ronald C. FABO Gold Member FABO Gold Member

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                How is the kick down being addressed?
                 
              • Cazbah362

                Cazbah362 Well-Known Member

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                Ronald, I agree - how is the 727/904 kick down being addressed with the Gen III EFI swap? One possibility is a manual valve body?
                 
              • Ronald C.

                Ronald C. FABO Gold Member FABO Gold Member

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                Surely a manual SB isn’t the only way to address. I thought I saw somewhere (can’t find it now) that a guy “piggy-backed” a throttle type cable, from the trans to the throttle body, maybe? Would that be applicable on an EFI drive by wire?
                 
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