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Thinking about putting a later model automatic with OD behind my 1966 318 poly

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  1. Bart K

    Bart KActive Member

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    My 1966 D 100 currently has a 318 poly with a 4 speed with a granny low and a 391 rear end. The speed limits on the freeways around where I live are 75 and most people run 80. With the current set up I have, it is hard to get 70 out of the old girl. I am sure someone has done the switch I am talking about, so I was hoping to get off easy and have someone tell me what I need to pull this off.

    I am told, Yes you can. The early 518 non electric is good or the electric that you can wire a switch for the od.The poly block only has one bell housing bolt that won't line up. Most just leave it without.No big deal.You will have to make some cross member mods. I only installed one in a car that required floor mods, I assume that a truck will be easier. Being it's a truck the 518 is the same as a non od 727.

    So guys, this is the first issue I am seeing. The 518 trans is the trans I was discussing with my transmission guy. The problem is that he claims the 518 would only work with the 6 bolt flywheel arrangement of the 318 engine, I have the 8 bolt version. Also, the 518 option requires driver input to switch on and off the overdrive feature. Failure to turn it off when not needed could potentially burn-up the transmission, according to my guy. Any comments on these issues?

    I am open to any and all information and guidance!
     
  2. 89on35s

    89on35sActive Member

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    I did a control scheme with pressure sensors off the governor port and a vacuum switch for kick down. This was in a Duster. PATC transmissions has a kit that is the same as what I did but cheaper than I found the parts for. As far as hitting overdrive when going too slow. OD does not engage till 3rd gear so I'm not sure if that would be an issue or not. Mine engages at about 50 mph.

    A-500 transmission OD and LU controls. - Read till the end as I made some changes from the first sketch.

    Cley
     
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    • Bart K

      Bart KActive Member

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      Thanks Cley, I will read up after work!!!
       
    • 89on35s

      89on35sActive Member

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    • Bart K

      Bart KActive Member

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    • paul massaro

      paul massaropomonamissel

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      why not a a833 od ?
       
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      • Bart K

        Bart KActive Member

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        I guess that is a possibility, will it bolt up? Do you know if anyone has done this before behind the poly 318?
         
      • 7mopar

        7moparWell-Known Member

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        The poly car bellhousing will not support it and the truck used an entirely different pattern. One from a 1980s 318 with the od trans would be a good fit.
         
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        • Bart K

          Bart KActive Member

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          Ok, thanks for the info 7mopar!!!
           
        • paul massaro

          paul massaropomonamissel

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          a bud of mine put a a833 behind his 392 hemi on a stock bellhousing , it required a spacer adapter for it to work . i can get with him about the adapter . he sold the motor less trans . DSC00996.JPG
           
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          • 7mopar

            7moparWell-Known Member

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            Did not the 392 use a different bellhousing than the smaller hemis. I know the older hemi 331 and such shared the same pattern as early 318. But that all changed.
             
          • paul massaro

            paul massaropomonamissel

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            no all those early hemi's and poly's used the same pattern , the early chrysler 331's had a long bell hanging out , but was cut back . so there all became the same , this is the same pattern used on the l 318 (poly) and la 273 318 340 360 . just different dowel pin locations , and the crank shaft hangs out more on those early motors or pre 58 motors . @Bart K . does your trans in your truck , does it have a 23 spline input like the a833 od ? and whats it measure from that bell mount to the clutch splines ? lets see if we can see whats what on these . the pickup a833 od has a .23 over gear . first is 3.09 to 1 . so it can leave easy , that poly has enough torque to care through the gears in that little p/u .
             
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            • Bart K

              Bart KActive Member

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              So a bit of new info. We actually pulled the trans and although the crank has 8 holes, only 6 are threaded, one is just a hole and the other has a dowel in it, so we actually DO have the 6 threaded hold crank.
               
            • 7mopar

              7moparWell-Known Member

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              Should work. When I obliterated the 318 poly the flywheel got attached to the 383 build. Both 6 bolt cranks.
               
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              • paul massaro

                paul massaropomonamissel

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                there was a727's behind that poly , should bolt right up . the crank should have the proper receiving bore for that converter , and the dowel pins are the right size and location for the 518 tranny bell mount pattern . just need to build a trans to frame mount and build a drive line . maybe grab a driveline you can shorten . your stock one won't work , to short to rework into a slip yoke type driveline . and the shifter , and speedo cable rework . you could up gear that truck 8 3/4 r/e with better gears as well .
                 
              • 7mopar

                7moparWell-Known Member

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                Paul do you know if the 500 and 518 used the same style transmission mount? I am trying to gather parts for a 518 install and have a 500 mount available if it will work. If not I need to keep looking or plan on building one.
                 
              • paul massaro

                paul massaropomonamissel

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                500 is weak , 518 is much better , both aren't as strong as a 727. not sure about them mounting the same although . i would think they should mount the same . there just a 904 and a 727 replacement for the new od vehicles . but much larger case to the rear of those 500 series trannys , compared to a 727 . i'm thinking your old bellhousing mount will get cut out of the truck , but you should put a piece back between the top and bottom of the frame at that rear of the front spring hangers were you remove that old crossmember .
                 
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                • 7mopar

                  7moparWell-Known Member

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                  Its an 82. I will unbolt the original transmission crossmember and will be saving it along with the front drive shaft section. If its just a 727 mount I will just build a new crossmember and forget about the 500 member and mount. My chances of finding a D350 with od are slim.
                   
                • paul massaro

                  paul massaropomonamissel

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                  i never said its like a 727 mount , i was just comparing the mounting placement at the trans , 727 and 904 is the same location between those two , the 500 and 518 will be the same as each other in location as well . and i looked at the mount usct offers to put a 518 were a 727 come from , there different as night and day , there are in different locations as well .
                   
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