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Tranny matchup for 454

Discussion in 'Chevy Trucks' started by 79GmcBigRed, Apr 19, 2004.

  1. 79GmcBigRed

    79GmcBigRed Junior Member
    from dsghsd
    Messages: 6

    Hey i just got a 454 that im gonna play with and build slowly. When im done im gonna drop into my half ton chevy. I have a brand new 350 tranny in there but if im not mistaking a 454 wont bolt up to a turbo 350. or will it? i dont really wanna buy a 400 or 700r4. any input on this would be appreciated cuz i dont really wanna get another tranny. thnx

    Trey
     
  2. Rick Loncosky

    Rick Loncosky Senior Member
    from 17557
    Messages: 102

    You just need the correct flex-plate for a 454, "externally balanced" and a torque convertor to match the cam and bolt her right up.
     
  3. ratplow408

    ratplow408 Member
    from PA
    Messages: 33

    Chevy bellhousing size is same for big block and small block. Just put 396 in my blazer with a 400 from 1 ton 2 wheel drive van. Van had a 350 motor in it. Big block went right in and tranny bolted right up. Plowed great all winter. You definatly need proper flexplate as mentioned above.
     
  4. karl klein

    karl klein Senior Member
    Messages: 557

    i thought the 396 was a small block?
     
  5. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    396 is a big block (as is the later 402 that replaced it), you are thinking the 400 small block.

    Chevy TH trannies all use the same bellhousing, unless they are from non-4.3 V6's (ie: 2.8 uses a more squared-off metric bolt pattern) so you could use any tranny you like. TH350 will probably work fine behind a stock 454 but more than that you are asking for trouble. Especially if you are plowing. Whatever tranny you choose, remember heat is your enemy so get the largest tranny cooler you can IN TANDEM (after) with the original rad cooler.

    My advice would be to seek out a TH400, even if you only plan to use it as a spare b/c I would guess that with the TH350 behind even a mild 454 in a truck application that it would only be a matter of time. 2wd TH400's are very common and reasonably priced--not sure what it would take to use it in a 4x4 b/c I've never done it....
     
  6. ratplow408

    ratplow408 Member
    from PA
    Messages: 33

    The 2 wheel drive 400 will mate right up to an np 205 transfer case with 400 to 205 adapter(get it at local GM dealer).Just take off the yoke and 6 bolts that hold on the rear housing. If the output shaft is sticking out 4.25" to 4.50" you have the right output shaft.
     
  7. The Boss

    The Boss 2000 Club Member
    Messages: 2,099

    A 454 will tear apart a TH350 in time. Go with a TH400.
    By the way, I have a Chevy 396 for sale if anyone wants it.:waving:
     
  8. ratlover

    ratlover PlowSite.com Addict
    from IL
    Messages: 1,325

    A 350 will live behind a 454 especially if you are running a 2wd truck and you arnt runing sticky tires at the track. You just wont be getting traction to nuke something.

    Get a transgo shift kit(stressing transgo) installed and run a big honking aftermarket cooler. If you kill it you can get one built up that will live fine.

    You shouldnt need a different converter because the added low end extra power in general will make the converter act more "lose" than it was behind the smaller motor. This is if you keep the build on a more moderate level. Dont go gonzo with the cam, run a dual plane manifold, and run some OVAL PORT heads. Merlin oval ports are good aftermarket heads but some good chevy castings will work great. If you can atall help it dont use "penut ports" and dont use "recangular ports"