1. camfreak1

    camfreak1 Member

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    Hey Gang!!!!! Help
    Im upgrading my 1972 Plymouth Scamp with a 318.
    The original Y pipe is about 1 3/4 to 2 the muffler shop says we need to chop the down pipe 6 inches from the flange and then connect a 2 1/4 pipe for the rest of the car.He says there is not a bender for the 1 3/4 pipe.
    Does anyone make a down pipe in a 2 1/4 that i can replace the original ones with or maybe a y pipe i can cut to fit. I really dont want to go with headers. Please give me some input or pics of what the rest of the members have done. Or is the muffler shop just pulling my Leg!!!!
     
  2. AJ/FormS

    AJ/FormS 68 Formua-S fastback clone 367/A833/GVod/3.55s FABO Gold Member

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    Of course there's a bender!; he just doesn't seem to have one.
    But in all honesty dual exhaust on a 318 doesn't really care about the size of the pipes. If his price is fair, just go with it

    But in even more honesty, a lo-compression 2bbl 318 daily driver with 2.76 gears doesn't need dual exhaust in any case. I won't say it's a waste of money but it more or less is.
    Why?
    Cuz the engine won't need it until maybe 3800 rpm at the very earliest, which is ~40 mph in first gear, and the 2bbl gave up quite a bit earlier, say at ~3400rpm.
     
    Last edited: Feb 18, 2021
  3. camfreak1

    camfreak1 Member

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    He wants to cut off at about 6 inches from the flange and continue with a 2 1/4 the rest of the way.
     
  4. dano

    dano Evil Handy Man

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    What do you mean by upgrade? Like will you be building your 318 or see a higher power engine int he future or just fixing the exhaust and trying to get something more free flowing.
     
  5. jazak5

    jazak5 Well-Known Member

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    just my 2c 340 hp manifolds/tti shorties ( i went with the 340hp's) and tti down pipes with a 2 1/2 pypes stainless exhaust like I did and be done with it even if you want to upgrade later with more ci your good do it once !
     
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    • camfreak1

      camfreak1 Member

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      Just really trying to get dual exhaust on a stock 318.
      Seems like we have a tight space near the flange and some weird bends.
      Anybody sell down pipes or a y pipe with correct bends.
       
    • Carofthemonth

      Carofthemonth Member

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      It's all about the sound. I dont need to go fast anymore. My daily driver is twice as powerful as my Duster but the 318 Duster with duels sounds much better!!
       
    • dano

      dano Evil Handy Man

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      Accurate LTD.

      -1967-74 A Body Exhaust Systems (Small Block)
       
    • AJ/FormS

      AJ/FormS 68 Formua-S fastback clone 367/A833/GVod/3.55s FABO Gold Member

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      I don't see anything wrong with that, besides the extra cost.
       
    • DartGTDan

      DartGTDan '71 Dart GT Fan

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      My 120,000 mile '71 Dart GT with the original 318 has an Edelbrock LD4B with a 1406 600 cfm carburetor. My exhaust consists of factory manifolds, FlowMaster 40s and 2 1/4" pipes.

       
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      • camfreak1

        camfreak1 Member

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        What did you do at the flange?
         
      • Lelo Dart

        Lelo Dart *

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        It should be fine as long as your down pipes aren't all rusted out and won't last as long as the rest of your new exhaust system. Gonna flow a lot better than a single exhaust and sound better too. Hopefully they will give you a little break on price for not doing the job completely. I had a dual exhaust done on a 72 Dart with 2 1/4" all the way to the exhaust manifold flange (so I know it is possible) but since the manifold outlet is 1.75" I gained next to nothing. Good luck!
         
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