Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

700R4 to TH400 swap.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ftn96, Sep 24, 2002.

  1. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    I have a TH400 with 208 adapter that I just picked up from Depdog...(thanks Glenn, it was nice shootin the breeze with you./forums/images/icons/wink.gif) I need to make sure I understand how to control the shift to my new implant. I'm under the impression that the 400's modulator is vacum controlled. So do I just tap into any ol vacum line and route it to the 400 modulator? or what?

    Thanks.
     
  2. R72K5

    R72K5 Banned

    Joined:
    Mar 5, 2001
    Posts:
    8,905
    Likes Received:
    0
    Location:
    central IL
    modulator valves are manifold vacuum controlled yep, factory always uses the threaded in piece just behind carb on top side of intake out in open back there


    good luck
     
  3. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    You can do a couple of things to change the shift points on a Turbo 400. You can buy adjustable modulators that will let you slightly alter the shift points. You can also buy different weights and springs to make big changes by altering the governor. The drag racing crowd uses that kind of stuff to fine tune the shift points to match up with the torque curves of their engines.
     
  4. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    I just need to know where to tap into the vacum on this 90 model and I don't want no more trick shifting crap. After all it's a 400 right? I don't need to worry about it like I did the 700. /forums/images/icons/grin.gif At least I hope.
     
  5. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    All it needs is direct manifold vacuum. Look around on the intake manifold for any vacuum ports and tee into one of those lines. /forums/images/icons/cool.gif
     
  6. Z3PR

    Z3PR Banned

    Joined:
    Mar 30, 2002
    Posts:
    19,217
    Likes Received:
    0
    Location:
    Everywhere
    I've tapped into the vac. line for the break booster befor, but I don't know if that was a good idea or not. It didn't seam to effect the breaks on that truck.
     
  7. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    10-4 my HAIR-E friend. /forums/images/icons/grin.gif
     
  8. wayne

    wayne 3/4 ton status

    Joined:
    Feb 1, 2001
    Posts:
    6,178
    Likes Received:
    0
    Location:
    Carlisle, Pa
    Here is a rundown since I just did the same swap a few weeks ago.
    If you look on the back of the intake you will see a silver piece comming up out of it. It threads in to the intake. Just use a T fitting in that line to tie into. Use hard tubing except on the ends where you tie into the T and into the modulator. Use hose on the ends. the trannie cooler lines bolt right into the th400. You might have to tweak them a bit if you want to use the clamp that bolts on the trans dust shield. The wires for the 700 just zip tie them up in the engine compartment. Just don't do what I did and after the swap with in 15 miles I blew the rear main seal on the engine. /forums/images/icons/crazy.gif I'm still to pissed to even think about pulling it apart again to fix it. /forums/images/icons/shocked.gif
     
  9. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Damn Wayne! Sounds like you have my luck. /forums/images/icons/smirk.gif
     

Share This Page