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Thread: Can I use a TH400?

  1. #1
    Deer Slayer 2FNFAST's Avatar
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    Can I use a TH400?

    Alright I am getting ready to buy a 78 Suburban with a 454/TH400. The 454 is for my full-size and I am going to take out the 357 for the s-blazer. What would it require to get the TH400 in the tunnel? I don't think they are any taller than a TH350 but, I know they are a little longer. Will I have to modify the x-member? Can I use the yoke off of the suburban and put it on my s-blazer's driveshaft? Are TH400s vaccum operated or what? I really don't understand these transmissions. Can someone explain in detail(if possible) how these work? Any help is appreciated! Thanks!
    88 S10 Blazer - Work In Progress 360 hp 350/TH400 coming soon....

  2. #2
    Deer Slayer 2FNFAST's Avatar
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    Come on guys I know you know something about these trannies...
    88 S10 Blazer - Work In Progress 360 hp 350/TH400 coming soon....

  3. #3
    16's or bust 91blazin2last's Avatar
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    what are you gonan do with the burb when you are done?
    Originally posted by bigjsp
    :rolleyes:

    Ba - bup - pa pa da dang ga dang dang yi dip ti ta dip - blue moon


    shoo be do wop!





    Just picture your grandparents "bumping uglies" in the back seat of a 57 chevy

  4. #4
    Senior Member bigjsp's Avatar
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    they work great, need vacuum, need to modify the x member, a good driveshaft shop will have a "crossover" u-joint to get the 400 yoke on your s10 driveshaft.

    The kick down is electronic normally run off a switch on the throttle pedal, but get a fun shifter and drive the bitch manually.

  5. #5
    Deer Slayer 2FNFAST's Avatar
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    What am I doin with it?

    the suburban will get the motor/trans takin out. Then, the 454 is either goin in the s10 or the k5. I am takin out the rearend for my k5 because it is a posi. But it's for sale after all that it is purple and is 2wd.
    Last edited by 2FNFAST; 03-10-2003 at 10:01 AM.
    88 S10 Blazer - Work In Progress 360 hp 350/TH400 coming soon....

  6. #6
    Senior Member bigjsp's Avatar
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    I had a 454 73 suburban that I ran at the college auto club autocross. Power braked it to get the tires smoking before the starters flag even dropped. Didn't win but was a crowd favorite. I'll try to find and scan a pic.

    I loved that truck, even carpet burned the tops of my toes in it :boink: at the drive-in watching American Werewolf in London during a summer lightning storm. Memorable evening, Sorry no pics.

  7. #7
    Deer Slayer 2FNFAST's Avatar
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    Will it hurt to drive the bitch like a manual?
    88 S10 Blazer - Work In Progress 360 hp 350/TH400 coming soon....

  8. #8
    Senior Member bigjsp's Avatar
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    No, a shift is still a shift. whether you intiate it or the kick down does.

    I had already clearanced the floor and firewall from when I had my Nash 5 speed in so I cant tell you how much hammering it will take from stock, only that it will fit.

    I've got a B&M Megashifter in my limo truck. My "drive" position still upshifts like normal and backshifts but it won't kick down based on throttle position. So if you are doing 45 and want to pass, you have to pull it back to second yourself. The current carbed 360 motor setup in the limo truck is built for towing my 26' fifth wheel camper and is pretty torquey but I still pull it back for big hills.

    The turbo400 in my twin engine truck in the attached picture has a tranny brake, manual valve body and a Hurst Lightning Rods shifter (they haven't made them for 6? years). You'll see three levers, One lever is P,R, N, 1, the next is 2, and the last is 3rd gear. Should be fun if I ever get it finished.
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    Deer Slayer 2FNFAST's Avatar
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    Have you ever seen a Big Block S10? I really am thinking about doing this. I don't know the dimensions of a bbc vs. a sbc I am gonna go do some research and see what all is necessary. Thanks for all of your help.
    88 S10 Blazer - Work In Progress 360 hp 350/TH400 coming soon....

  10. #10
    Fully Erect Member LowKat's Avatar
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    Yea a big block will fit. Bolting positions are the same as a small block. I think you need 70's Chevelle/Impala exhaust manifolds and move the steering column over a little more than for a small block.

    I'm trying to locate a "deal" on a Bravada with a bad engine.
    Got a 1970 360HP 454 oval port engine.
    can you say... big block AWD :bigthumb:
    Originally posted by Blazin Low:
    In 1972 a crack commando unit was sent to prison by a military court for a crime they didn't commit. These men promptly escaped from a maximum security stockade to the Los Angeles underground. Today, still wanted by the government, they survive as soldiers of fortune. If you have a problem, if no one else can help, and if you can find them, maybe you can hire Tony Low
    :D

  11. #11
    Deer Slayer 2FNFAST's Avatar
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    So I could just use the motor mounts for the sbc and bolt them to the 2.8 pads? What about changing the dist. cap?
    Thanks
    88 S10 Blazer - Work In Progress 360 hp 350/TH400 coming soon....

  12. #12
    Senior Member bigjsp's Avatar
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    If you haven't done a swap yet, a big block will be a big challenge for you. Just about everything needs to get built bigger and stronger. cooling, exhaust, rear end, tranny cooler, fuel system..... then can you afford to drive it.

    Don't get me wrong, it will make you VERY distinguished but it isn't a bolt together that people can go read their JTR books and bail you out. The motor is going to fit in just about 1 place everything else must be built around or modified to clearance its position.

    I originally had a 14-71 blower and crank, rods and pistons for a 605 when I cut up the firewall with the intention of doing a radical set back to get the best weight transfer but I sold off the engine pieces :mad: and after having already deleted the firewall and floor and putting in the rollcage I conjured up the twin engine truck project.

    I have looked at updating my limo truck with a 454 but have elected to put an LS1 in next winter for performance and better fuel economy. I'd like to do a 480E tranny but the LS1motor/ 6speed/ computer from the donor car had the manual tranny computer obviously so I'm keeping the 400. Won't have to worry about no stinkin distributor:D
    Last edited by bigjsp; 03-11-2003 at 02:55 PM.

  13. #13
    Deer Slayer 2FNFAST's Avatar
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    Honestly I think my 357 will have about as much horsepower as the 454 but I know horsepower doesn't win races torque does. I might start dicking around once I get the motor out of the burban. I might buy some mounts and see how well it does/doesn't fit. Thanks for all the input.
    88 S10 Blazer - Work In Progress 360 hp 350/TH400 coming soon....

  14. #14
    Deer Slayer 2FNFAST's Avatar
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    I am real close to buying the burban I just need to sell my 305 and I am ready to go buy it. I still haven't figured out how to use the Th400. I don't want to drive it like a manual I want to be able to put it in drive and do just that. I really don't understand these transmissions. Will I have any trouble getting the kickdown to work? I am scared of it. lol
    88 S10 Blazer - Work In Progress 360 hp 350/TH400 coming soon....

  15. #15
    Burnout!!! badassblazer01's Avatar
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    My friend has a 454 in his s-10. It's sitting next to my blazer in my dad's garage. We just got it fired up a couple of days ago. That thing sounds good too. He had someone build the headers for him. That was the biggest problem on the truck. The BB is about 2"-3" longer than a SB too. It can be done though.

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