Best year(s) 904 for a street/strip car?

Discussion in 'Mopar Racers Forum' started by motorpirate, Jul 11, 2018.

  1. motorpirate

    motorpirate serial mopar owner

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    Another thing on the back burner, After I get the rear diff sorted out (eBay used 3.55's are whiney junk!! replacing this week with a virgin set) we are going to start the Magnum swap.
    At first this will be on the '66 904 original to the car (18 spline converter) which works fine, but if i am going to go into it to better suit the Magnum set up I think it makes sense to build a 27 spline trans to have a better choice of convertors, etc.
    Plus that will leave me with a fine running 273 2bbl/904 combo to put in Dads '48 dodge?

    So, what year/years would be the best to look for? Car is a'66 Barracuda weighs 3400.
    3.55 rear and will be driven to the track about 40 min away on the interstate at 65/70 mph.
    Will NOT be a manual valve body.
    If i know what to look for, while Dany and I are busy with the motor, I can keep my ear to the ground, I know I can kick up a good core to go through, if I know what year range to look for.

    Again, thanks for all your help guys!!
     
  2. xLURKxDOGx

    xLURKxDOGx "An angel fat, at satan's feast"

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    My experience has been with the latter years 70+ but only to simplify the torque converter debacle.

    Jake
     
  3. 70aarcuda

    70aarcuda Master Hoader of SBM FABO Gold Member

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    I believe it is the 72 oe 73 and newer is what you want...one of the servos changed..
     
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    • motorpirate

      motorpirate serial mopar owner

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      And how to tell what year a trans is, if it's not in the car???
       
    • 72Dart6pack

      72Dart6pack Harder Better Faster Stronger.

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      Casting dates on the parts are a good start.
       
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      • cosgig

        cosgig MoBro Inc. FABO Gold Member

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        The 66-67 904 does have a front and rear pump, if that makes any difference. And the converter debacle is easily overcome with an annular ring.
         
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        • 70aarcuda

          70aarcuda Master Hoader of SBM FABO Gold Member

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          on the driver side just on the pan rail...there is a number stamped that starts with a PKxxxxxxxx then xxxxx
           
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          • crackedback

            crackedback FABO Gold Member FABO Gold Member

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            71+ are the better ones IIRC. There is a difference on the outer case where the Servo is located as Tony mentioned.
             
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            • motorpirate

              motorpirate serial mopar owner

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              is a front and rear pump any advantage?
               
            • Mike 340

              Mike 340 Well-Known Member

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              I think that you could push start with a rear pump. ?
               
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              • Charrlie_S

                Charrlie_S Well-Known Member

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                1965 was the last year with a rear pump.
                 
              • furrystump

                furrystump Well-Known Member

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                I know there were 904’s that came with a 5 clutch drum. I don’t know the specific year, but I think you can build any 904 to survive behind a pretty serious motor. I know of a 5 clutch 904 in small block demon that runs 11.70’s and it’s not even working hard
                 
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                • mderoy340

                  mderoy340 Well-Known Member

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                  Vin# pad will also tell year.
                  I run a 84 lockup 5 clutch low gear set from a Diplomat. TF2 shift kit, lockup circuit plugged, Turbo Action 10" S800 26 spline 3200 tight converter, 3.91 gear. 340 375-400 real world hp, Launch car at 2k 1.65 60', 11.77 best so far in ok air. I pulled the tranny after 400 passes and it looked good so it when back in with new seals only. Lockup input shaft is plenty strong for what I'm doing street/strip drive 100 miles round trip to the track.
                   
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                  • motorpirate

                    motorpirate serial mopar owner

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                    So sounds like I'm looking for a Volare/Diplomat/5th Ave trans..
                     
                  • 70aarcuda

                    70aarcuda Master Hoader of SBM FABO Gold Member

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                    the 4 disc drums can be outfitted with 5 disc....just have to use the thin .068 clutch disc instead of the 086 thickness....I got 4 904 like that......
                     
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                    • rumblefish360

                      rumblefish360 so close yet so far away

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                      Do tell about this annular ring!
                       
                    • Charrlie_S

                      Charrlie_S Well-Known Member

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                      67 down 904 had a small input shaft, and pilot on the engine end of the converter. This matched the size of the pocket in the end of the crank, for small blocks, and slant sixes. In 1968 the crank pocket, converter pilot, and input shaft got larger. This is why you cannot put a 67 or earlier engine, up to a later trans. You can put a later engine up to the early trans buy using an adapter ring in the end of the crank.
                       
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                      • 408 swinger

                        408 swinger FABO Gold Member FABO Gold Member

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                        Isn't the output a little latger on the 73 up, also?
                         
                      • Charrlie_S

                        Charrlie_S Well-Known Member

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                        If you mean the output shaft where the front drive shaft yoke slides in.
                        No. 1966 up all the same. 1965 down, has the flange.
                         
                      • 408 swinger

                        408 swinger FABO Gold Member FABO Gold Member

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                        go
                        Gotcha!
                         
                      • rumblefish360

                        rumblefish360 so close yet so far away

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                        Thanks Charlie. For some reason, I thought it was an adapter ring on the trans to use a later converter.
                         
                      • Charrlie_S

                        Charrlie_S Well-Known Member

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                        Just a FYI
                        I used to get my converters built (hard to get them now) with the small pilot, and the large splines. That way I could use the early engine with the late trans. Or use the early trans, by changing the front pump and input shaft, to the late items (they will interchange). Or use the late engine, by using the adapter ring. Gives me more options.
                        PS: I like to use the pushbutton trans with the late front section parts, with either late or early engines.
                         
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