K member & 400 B Big Block question.

FABO Welcome Wagon

  1. Cudaman77

    Cudaman77 New Member

    Messages:
    4
    Likes Received:
    0
    Joined:
    Sep 30, 2019
    Location:
    Grove City, Pa
    Local Time:
    2:31 AM
    Hey all, I just bought a 1967 Barracuda that started life as a slant 6 but was converted to a 318. I know there’s a difference between slant 6 and V8 K members but, is there a difference between Small Block and Big Block K members? I’m looking to build my 400 and run it in my Barracuda but was asked if the K members were different. Also does anyone know if the stock 400 crankshaft is good to run 400+ hp? If not what crankshaft is there to run without making it a stroker motor.
     
  2. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack

    Messages:
    55,776
    Likes Received:
    24431
    Joined:
    Jun 7, 2010
    Location:
    Georgia
    Local Time:
    2:31 AM
    Yes big and small block k frames are different. The stock cast cranks are good to 600 HP with good machine work, good balancing, good lightweight parts (like you would use anyway) and good assembly. They will hold up just fine.
     
  3. Cudaman77

    Cudaman77 New Member

    Messages:
    4
    Likes Received:
    0
    Joined:
    Sep 30, 2019
    Location:
    Grove City, Pa
    Local Time:
    2:31 AM
    Thank you for that information. Do you know by chance what size connecting rods I would need for a stock stroke 400? Also where to look for a big block k member?
     
  4. Oldiron440

    Oldiron440 Well-Known Member

    Messages:
    291
    Likes Received:
    270
    Joined:
    Jan 12, 2019
    Location:
    North central Iowa
    Local Time:
    1:31 AM
    400 cast crank horse power level 500 or less but you can use a 383 crank in the 400 block. :thumbsup:
     
  5. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack

    Messages:
    55,776
    Likes Received:
    24431
    Joined:
    Jun 7, 2010
    Location:
    Georgia
    Local Time:
    2:31 AM
    It depends totally on how you build it. Stock length for the 400 is 6.358. Some use the 440 rod. It is 6.760. Pistons are readily available for both, I believe.
     
  6. Cudaman77

    Cudaman77 New Member

    Messages:
    4
    Likes Received:
    0
    Joined:
    Sep 30, 2019
    Location:
    Grove City, Pa
    Local Time:
    2:31 AM
    Any recommendations on finding a forged 383 crank. All sites I’m finding are using a 440 crank and different rods.
     
  7. Oldiron440

    Oldiron440 Well-Known Member

    Messages:
    291
    Likes Received:
    270
    Joined:
    Jan 12, 2019
    Location:
    North central Iowa
    Local Time:
    1:31 AM
    Yep that makes a 451.
    You just have to keep looking, it should be cheap when you find one because nobody uses a 383 crank anymore. If you really want to find one look for a 413 crank and you will find 6 383 crankshafts. :)
     
  8. Car Nut

    Car Nut Mopar Master

    Messages:
    4,793
    Likes Received:
    19644
    Joined:
    Dec 28, 2018
    Location:
    Zombieland
    Local Time:
    12:31 AM
    :welcome: aboard!
     
  9. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack

    Messages:
    55,776
    Likes Received:
    24431
    Joined:
    Jun 7, 2010
    Location:
    Georgia
    Local Time:
    2:31 AM
    They'll take more. Chrysler never used "just" cast iron like Chevy. They used nodular iron, which is a good bit stronger. I always give Ford's 351 Cleveland as an example. They never came with a steel crank, but nodular iron. These engines routinely saw 9500 RPM on the NASCAR circuit using the nodular iron crank. Nodular iron cranks can live quite well with good prep work and parts.
     
  10. Oldiron440

    Oldiron440 Well-Known Member

    Messages:
    291
    Likes Received:
    270
    Joined:
    Jan 12, 2019
    Location:
    North central Iowa
    Local Time:
    1:31 AM
    But there's no reason to find out, a 383 crank is what you need.
     
  11. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack

    Messages:
    55,776
    Likes Received:
    24431
    Joined:
    Jun 7, 2010
    Location:
    Georgia
    Local Time:
    2:31 AM
    Yes, they're cheap enough. But plenty of people have done it and already found out. It's no secret. I'm not trying to argue, just stating facts.
     
  12. Oldiron440

    Oldiron440 Well-Known Member

    Messages:
    291
    Likes Received:
    270
    Joined:
    Jan 12, 2019
    Location:
    North central Iowa
    Local Time:
    1:31 AM
    I see, I've always regretted not using the best parts I could afford in the shortblock. It seams it's one place sooner or later you build for more power and all the sudden your up against the limits of the shortblock. With today's heads it's very easy to build over 500 hp in a big block so why limit yourself?
     
  13. Mopar-Mitch

    Mopar-Mitch Well-Known Member

    Messages:
    1,584
    Likes Received:
    1623
    Joined:
    Jul 29, 2018
    Location:
    Kentucky
    Local Time:
    1:31 AM
    Welcome! from Kentucky! :welcome:
     
    • Thanks! Thanks! x 1
    • RustyRatRod

      RustyRatRod 30 Degrees Outta Whack

      Messages:
      55,776
      Likes Received:
      24431
      Joined:
      Jun 7, 2010
      Location:
      Georgia
      Local Time:
      2:31 AM
      Oh I don't know? I always thought not having all the money in the world was a good limiter. I'm happy for you that you don't have that limiting factor.
       
    • ragtopfury

      ragtopfury Well-Known Member

      Messages:
      2,464
      Likes Received:
      1569
      Joined:
      Jul 14, 2011
      Location:
      Manchester, MD
      Local Time:
      2:31 AM
      You say your car started life as a /6 and is now a 318..... was the K-frame changed for that swap, or did the prior owner use a conversion motor mount? You might still be working with the original /6 K-frame........ Or, and I should know this, but can't remember - are the /6 and 318 K-frames the same?
       
    • RustyRatRod

      RustyRatRod 30 Degrees Outta Whack

      Messages:
      55,776
      Likes Received:
      24431
      Joined:
      Jun 7, 2010
      Location:
      Georgia
      Local Time:
      2:31 AM

      On his (67 forward) I think the slant and small block k members are different. They are the same 66 and back. @Jim Lusk will tell us for sure.
       
    • Oldiron440

      Oldiron440 Well-Known Member

      Messages:
      291
      Likes Received:
      270
      Joined:
      Jan 12, 2019
      Location:
      North central Iowa
      Local Time:
      1:31 AM
      I've got a 440 first build in 88 it's just a TRW blue printed build. So it's been decked and compression is 9.5 for street use with polished stock rods. There are no trick parts what so ever but this shortblock has over 2000 pass's and a few more street miles. I've run it to 7000 rpm from the second pass on. It's got a pair of 452 heads and a old 557 cam now, we thrue it on the dyno and it made 520 hp 545 tq. I built the 440 at a time when I had no cash and needed to barter all the machine work (I did bodywork and paint). But my point is build a solid shortblock because you might be living with it for awhile.
      If your lucky !
       
    • RustyRatRod

      RustyRatRod 30 Degrees Outta Whack

      Messages:
      55,776
      Likes Received:
      24431
      Joined:
      Jun 7, 2010
      Location:
      Georgia
      Local Time:
      2:31 AM
      I agree 100%. I've always used what I had, because I had to. Only a few of my personal builds had nice stuff in the bottom. Done a good bit for others. Even this 396 I have built. It's a cast crank, cast piston engine. In its defense, the pistons ARE original heavy duty GM pieces. They are pretty nice for cast pistons....very much like the older cast Chrysler pistons. They are stronger than most give them credit for. But I cannot and will not argue your logic. You're 100% correct.
       
    • Cudaman77

      Cudaman77 New Member

      Messages:
      4
      Likes Received:
      0
      Joined:
      Sep 30, 2019
      Location:
      Grove City, Pa
      Local Time:
      2:31 AM
      The K member is the slant 6 one but the previous owner relocated the motor mount and welded it back on. I know there are motor mount relocation kits from Schumacher can I use those or will it be to much stress on the K member? Thank you guys for all of the help. I have a lot more to think about then I thought. Looking for cheap but at the same time quality parts
       
    1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
      By continuing to use this site, you are consenting to our use of cookies.