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700r4/241 to th400/205 conversion????

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by wayne, Aug 16, 2001.

  1. wayne

    wayne 3/4 ton status

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    I am planning to swap my 700r4/241 to a 400/205 soon and have some ?'s on doing the swap. I was hopeing to hold off on this till next year but my 700 has alot of miles on it and I think it is about due for a rebuild. I plan on doing a doubler in the future and I can get the 400/205 dirt cheap so I plan to just swap it now. I am going to be getting most of the parts out of a Burban so I need some input from anybody that has done the conversion. So here are the ?'s:
    1. I have TBI and need to know if there is a special bracket or anything I need to hook up the kick down cable?
    2. The 400 should have a modulator valve? If so where should I tie in for vacume?
    3. Will the crossmember from the Burb work in the K5?
    4. Is the 4wd shifter location going to be in the same place as the 241 is?
    5. Is there going to be any affect on the computer being the 400 does not have a lock up converter?
    6. Speedo cable. Should I just take the one from the burban or do I need something differant?
    I can't think of anything else but those who did the swap can probably point me in the direction I need to go. Thanks.

    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue> <P ID="edit"><FONT class="small">Edited by wayne on 08/17/01 12:19 AM.</FONT></P>
     
  2. MudbogAD

    MudbogAD 1/2 ton status

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    Re: 700r4/241 to th400/205 conversion

    I really don't know too much about the swap but I do know the crossmember will fit from the burb to the k5. That is a good swap in my opinion because of the strength. You will have the strongest auto tranny and transfercase that you can get from the price range.

    Adam
    79' Jimmy
    3.08's(sucks)
    35's(Bigfoot MT's)
    Np 205, th350, 12B, 10B
    3" suspension lift
     
  3. wayne

    wayne 3/4 ton status

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    Re: 700r4/241 to th400/205 conversion

    I figured the crossmember would fit but wanted to be sure. I also believe the shifter location will be the same too but want to be sure on it too. I don't think it will be that hard of a swap and that should put me a step ahead for doing the doubler.

    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  4. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Re: 700r4/241 to th400/205 conversion

    As far as the modulator goes, manifold vacuum is what you want. There should be a plug in the intake kind of kiddy corner to the back side of the carburetor on the passenger side. Put a copper nipple on there and run a hose down to the modulator. If you can use steel hose for most of the distance with two shorter pieces of rubber on either end you will have less chance of snagging it or leaks.

    There is a Right way, a Wrong way, and then there is My way. The latter is usually the most fun! [​IMG]
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: 700r4/241 to th400/205 conversion

    The shifter for the 205 is totally different. I am pretty sure it's not in the same location, but either way, it's totally different.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  6. wayne

    wayne 3/4 ton status

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    Re: 700r4/241 to th400/205 conversion

    I know the shifter is differant, what I am tring to find out is will it come up through the existing hole in the floor or will I need to cut a new one?

    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  7. RGF

    RGF 1/2 ton status

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    Re: 700r4/241 to th400/205 conversion

    The TH400 doesnt have a kick-down cable, it uses a elec solenoid and switch on the gas pedal bracket
    700R4s and TH400s are about the same lenght so you may get lucky on the shifter hole location,I changed from a TH400/NP208 to a TH400/NP203 on the yard truck and didnt have to do anything except remove the 208 shifter stuff.
    Not sure about the speedo stuff, I know the NP241 that was in a 90Blazer I had didnt have a cable but a elec. sensor on it.
    RGF
     
  8. wayne

    wayne 3/4 ton status

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    Anybody?????

    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  9. shupach

    shupach 1/2 ton status

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    well seeing how everyone says that the shifter is different here's wat i would do. I'm doing a SM465/205 swap and i noticed that there is this plate around my 203 shifter that is bolted in. I figure that in my parts truck it will have the same plate however with all the holes for the 465/205 already cut. So i figure i'll just swap em instead of having to cut holes.

    my 2 cents, good luck wayne,

    phill
     
  10. wayne

    wayne 3/4 ton status

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    I know somebody has to have done this.

    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  11. wayne

    wayne 3/4 ton status

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    OK I looked at the Burb real quick today and the shifter looks like it will come through the same place as mine does now. Also it is an 80 so the 205 is slip yoke so I will have to convert it to a fixed. Should have more time to look into it more tomorrow but any help on this is greatly appreciated.


    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     

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