1973 Dart Sport Improvements

Big Block A body Tech

  1. Standonit1972

    Standonit1972 FABO Gold Member FABO Gold Member

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    I have a 73 dart sport with a 383/727 setup.The engine is a 1971 model .030 overbore, has a good cam (specs unknown) a good set of 1 7/8 headers, full 3 inch exhause, a weind single plane intake, and a holley 750 dp. The rear axle houses a 3:55 posi. Its been running pretty consistent 13.20's. I am looking to get it down in the low 12's high 11's this year. I have a set of ported 906 heads I am going to install that flow equivalent to edelbrock rpms soon. What do you guys think will help me meet my objective?
     
  2. Plymouth 65

    Plymouth 65 Floorable Deplorable

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    First, you need to determine what you have in that 383 build. CR and cam specs are a must have. You should also know what stall converter you have in that 727. Increased flow of the heads will help but the 88cc open chamber of the 906 head may lower your CR. 65'
     
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    • cawcislo

      cawcislo Well-Known Member

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      Can you add some more info to help us help you? A time slip breakdown with 60' and other info. Purpose of the vehicle is it a drag car only or street strip or cruiser mostly? Any opportunities for weight loss? Gearing can really help at the track, how high of a rear gear ratio could you live with?
       
    • Standonit1972

      Standonit1972 FABO Gold Member FABO Gold Member

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      The car has a 3000 stall convertor with a manual valve body.I also drive this car on the street. I am not against a rear gear change. I wish I knew more about this engine but I don't. Stock uncut heads, I believe 9 to 1 compression. The ported 906's have crane ductile iron rockers as well.
       
      Last edited: Jan 22, 2020
    • Standonit1972

      Standonit1972 FABO Gold Member FABO Gold Member

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      This car has a complete interior and its all steel.
       
    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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      A 12.0second quarter is a P/W (Power to Weight ratio) of .108 with SuperStock unlimited suspension.
      With street suspension you'll need to target about another 1/2 second; so.... .120
      If your car weighs 3600 with you in it, then .120x3600=432 hp. That's about what you are gonna need.
      And the gears,tires,wheels, stall, etc to optimize it.
      Your speed to go with that .108 is about 110, so after your engine comes back from the dyno-shop you can eyeball the power-chart and find the rpm of peak-power, and select the gears you need.
      That engine is gonna need a pretty big cam, so the gears are likely gonna come in around 4.10s/4.30s , and a maybe a 3800stall (I'm guessing),so this would not be my idea of a good streeter. Without the big cam, you're gonna have to spend the money on the heads.
      Don't forget the support works. At this power level, the cooling system needs to be top-notch. The fuel system and ignition systems will also have to keep up; and the trans has to not blow up, etc.
      Every 10 pounds you can lighten your car is worth about 1 hp. So if you can diet 150/180 pounds, that's about 1 cam size.
      As to weight;the heater is ~16, fold-down rearseat~64, 73 non-shock-absorbing bumpers and brackets gotta be at least 40/50 apiece, one steel wheel weighs about what two mags weigh. The power-steering system is ridiculously heavy; dual 3" exhaust with a pr of 3-pass long mufflers is about 72; Forget A/C.
      the point is this; 200 pounds is doable, even 250, but now yur leaving streetable behind. And driving to the track, then dropping the exhaust, and unbolting the bumpers, is not a lot of fun for me. Not to mention no heat or defrost. And without the fold-down rear seat; I guess you'll be staying in a Campground unless you managed to convince your wife to come... then it's Motel only anyway.
      Low12s/hi11s on all motor, ain't cheap with a modest engine.
      But just about any old 383 will get there by Nitrous.... even with your 3.55s and 3000Tc.Crank it up!.
       
    • Standonit1972

      Standonit1972 FABO Gold Member FABO Gold Member

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      This car used to be a drag car. It’s got weld drag lites, no heater box, msd ignition components, 3 inch exhaust with the small flowmasters, a good fuel system, and a griffin radiator and electric fan. Other than the heater box the interior is all there. I have thought about going to 4:10 gears, swapping to a glass hood, and gutting the interior. I also considered going to glass bumpers.
       
    • oldkimmer

      oldkimmer FABO Gold Member FABO Gold Member

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      Do a 440 to pass ur goals. Kim
       
    • Standonit1972

      Standonit1972 FABO Gold Member FABO Gold Member

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      I may do that next year. This year I am going to run the 383 that I have.
       
    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      Would be nice to know the cam specs. Are you milling the 906s?

      What did it mph at 13.20?
       
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      • Standonit1972

        Standonit1972 FABO Gold Member FABO Gold Member

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        Not Sure. I bought this car recently from its long time owner. The engine is an unknown and its internals are a mystery at this point. I will be doing some work on it though and hope to be able to answer some of the questions I have.
         
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