Upgrading help.

Slant 6 Engines

  1. Tduff01

    Tduff01 Well-Known Member

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    I have a 72 225 slant six that is is my duster. Wanting to upgrade a few things for a little more fun but not sure where to get stuff from. I was thinking intake, carb, and headers? What does everyone out there recommend. Nothing major just simple seeing as I have a 340 I will build for this one one day. I'm not even sure who makes upgrade parts for these and where to get them. What's everyone's thoughts?
    I also need the throttle cable bracket for this 72 225 if anyone has one out there one they would like to get rid of.
    Thanks in advance.!
     
  2. Charrlie_S

    Charrlie_S Well-Known Member

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    Why does everyone think intake/exhaust is he way to go with a slant six. This is a low compression engine (7.8-8.0 to 1). The most improvement for the money, is to raise the compression. Pull the head and mill it between .060 and .100, depending on the results you are looking for. You should take measurements, and find out how much to mill, to get the CR between 8.7, and 9.2 to 1 for a street car. While the head is off, you can do a valve job (if necessary), and a little pocket porting in the bowls. It is a little more work, then a manifold change, but actually should cost about the same or less, and will give better results. There is no downside to doing this. It increases engine efficency, increases torque, horsepower, and fuel mileage (have your cake, and eat it too). After that any other mods, like cam, manifold (intake/exhaust) carb, will have bigger gains.
     
    • Agree Agree x 1
    • nm9stheham

      nm9stheham Well-Known Member

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      Charlies_S is spot on for the compression... but some folks are not comfortable with tearing into an engine's innards.
       
    • TF360

      TF360 Well-Known Member

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      Yea, Charlie it's to complicated to do all that. He's looking for bolt on's. Check Clifford performance and Aussie Speed.
       
    • Charrlie_S

      Charrlie_S Well-Known Member

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      The OP might not think it is to complicated to mill the head. In my opinion, it is a minor addition, if the manifolds are already off. It will enhance the results of a manifold swap, and alone, actually gain more power, then just a manifold swap.
      But that's my opinion, that I'm throwing out there. The OP needs to decide what is best for him.
       
    • /sixchall

      /sixchall Well-Known Member

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      Tduff01 I have to agree with Charrlies_S the best single way for a higher torque value and some HP's is to shave the head to gain 9.2 comp. ratio so you can still get the CR to a point where you can still pull up the gas pumps with the 2 octane ratings that are left. I'm one of those people that worked around the shaving of the head thing. Instead, on my '70 Challenger w/ a '77 SL6 I added a Super Six set-up, carter bbd 280 CFM , MOPAR elec. ign. HO coil, open element K&N filter, Hooker headers, real SS 2 1/4" dual exhaust w/ "H" pipe all the way to back w/ glasspaks. Maybe I should consider now to be more efficient is to shave the head. Last modification for it. Thanks, Al
       
    • 67belevdere/225

      67belevdere/225 Well-Known Member

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      I just did the Clifford kit , I love it . I would go that way for sure
       
    • nm9stheham

      nm9stheham Well-Known Member

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      What exactly is the 'Clifford kit'?
       
    • /sixchall

      /sixchall Well-Known Member

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      I'm thinking what is meant by "Clifford kit" most likely a 4 bbl Clifford alum. manifold and an appropriate CFM 4 bbl carb and maybe Clifford headers or a set of Doug Dutra headers. Aussie Speed makes some really over the top intake manifolds, bit pricey, I think, but none the less a very aggressive piece of performance equipment. Hyper Pak style. Thanks, Al
       
    • TF360

      TF360 Well-Known Member

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      67 belvedere which kit. Any issues installing?
       
    • 67belevdere/225

      67belevdere/225 Well-Known Member

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      i did the twin weber kit . i have a automatic . so you need to sort out the kick down . it s pretty easy .
      i ceramic coated the headers , also then ,mad a custom stainless exhaust
      it s got plenty of power , loves it above 4000 , i'm very satisfied with it over all.
       
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