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396 Big Block and 700R4?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by derek2002, Feb 2, 2001.

  1. derek2002

    derek2002 1/2 ton status

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    A buddy of mine has a '82 Chevy truck. He just put a big block (396 - mild cam) in it. Two days later, he blew the tranny (700R4). The shop says it needs rebuilt.

    Should He:
    A) Upgrade to 350/400 Tranny?
    B) Rebuild his 700R4 ($650) with heavy-duty parts?
    C) Buy brand new 700R4 Jasper ($1700)?

    Let me know what you guys think. Also, would his NP208 bolt up to a 350 or 400 w/o an adapter plate? The only thing else he would need for the conversion would be driveshafts, correct?

    Later,

    -Derek
    1986 3/4 Ton & 1987 Blazer Project
    <A target="_blank" HREF=http://www.4chevy.com>http://www.4chevy.com</A>
     
  2. CK5

    CK5 In my underwear Administrator Premium Member GMOTM Winner Author

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    400

    A 650.00 700r4, please, that thing would blow up driving out of the parking lot, about the only 700 that would work behind a BB is an Art Carr 700, but they are around 3,000.
    Go with a 400/205 if you can, I know a lot of the military stuff came with a 400/208 combo and most of those get bought for the axles so finding that combo should be fairly easy.

    Steve
    [​IMG]
    Mall-Running poseur 4x4 with curb-feelers
     
  3. ftn96

    ftn96 1/2 ton status

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    I'd go 400 as the trucks have a little longer wheel base and the the 400 is a little longer than the 700R4 so you should be able to swap it in and still have room to get your driveshaft angels to match closely. If he can get the 205 go with it. But your gonna need to find them matted to avoid buying an adapter. The 208 should bolt right up to a 350, as it has a 4 bolt pattern same as the 700, but the 400's have a 6 bolt pattern for the t-case. The 208 is a decent t-case.
    but if he wants to go for easy and cheap, and still be pretty strong, you said mild cam, I'd feel safe going with the Th350, as it should be a direct replacement for the 700 with a slight slight difference in the driveshaft length. But the Th350 adn 208 should bolt right up. Hope all this helped, and I may have gotten somethings mixed up there, but I think it is all correct. Somebody else want to proof read?

    I know you all are going to say "400" all the way. But the 350 has a little bit lower range of gears compared to the 400 and it has proven itself over the years before the 700 came out. My recommendation is the 350, less he has a money tree in the back yard.
    oops, one more thing, you may need to check on the output shaft length difference from the 700 to the 350, I think the 350 output shaft is a bit shorter than the 700 output shaft, so if he gets the 350, have it built and have them put the longer output shaft in.

    Will work for beer, parts and tools.
    90 Jimi,350/700R4/241/10bolts/4.10's/33's/4"
    <A target="_blank" HREF=http://www.nashvillek5.freeservers.com>http://www.nashvillek5.freeservers.com</A><P ID="edit"><FONT SIZE=-1>Edited by ftn96 on 02/02/01 08:07 AM (server time).</FONT></P>
     
  4. Wheels

    Wheels 1/2 ton status

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    The 350 and the 700 have different output shafts. They are both 27 splines but they differ in length. The 350 wont have enough shaft in the transfer case and about the first time he romps on it, more than likely, he'll strip it out.
     
  5. ken

    ken 1/2 ton status

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    The 400 and 700 are so close in length, you don't need any driveshaft mods. I just replaced my 700 with a 400 and everything, including the stock crossmember, bolted right up. I had to obtain the 400-241 adapter, and change the input gear in the transfer case to match the 400's 32 spline output, but that was about it. That was after blowing up 6 700s behind a STOCK 350!!

    ken
     
  6. ftn96

    ftn96 1/2 ton status

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    I think advance adapters chart shows the length of the 400 to be a little less than an inch longer than the 700. thats not too bad, but that damn adapter is around 420 bones. I'd go 400 if I had the money, but if money is the issue, the 350 would be cheaper. Thats all.

    Will work for beer, parts and tools.
    90 Jimi,350/700R4/241/10bolts/4.10's/33's/4"
    <A target="_blank" HREF=http://www.nashvillek5.freeservers.com>http://www.nashvillek5.freeservers.com</A>
     
  7. ken

    ken 1/2 ton status

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    You can source the parts you need for yourself to mate the 400 to the 241. I happened to have an adapter from a 400 to a 208, which works for a 400-241 combo. Then I had to purchase the 32 spline input gear for the 241, which was $142...so, if you had to buy the adapter, say $75 from a wrecking yard, you're in the adapter for half of what Advance Adapter charges.

    ken
     
  8. ftn96

    ftn96 1/2 ton status

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    If only there were some decent yards around here.

    Will work for beer, parts and tools.
    90 Jimi,350/700R4/241/10bolts/4.10's/33's/4"
    <A target="_blank" HREF=http://www.nashvillek5.freeservers.com>http://www.nashvillek5.freeservers.com</A>
     
  9. laketex

    laketex 3/4 ton status

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    SM465/NP205. Just try to blow it up.

    [​IMG]
    Durant, Ok
    I love my SAWZALL!!!
     
  10. HarryH3

    HarryH3 1 ton status Author

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    Yeah, I'd toss the 700. Even Art Carr's megabuck beefed 700r4 is only rated to handle about 450 lb/ft of torque, max. A mildly built 396 should be able to tax it quite frequently. It may hold up, by why risk it? The difference in price between it and a 400 would pay for a LOT of gas! [​IMG] I'd go for a Turbo 400 or a beefy manual tranny like an NP 465 or a NV4500 (serious $$$ for the last one!)

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     

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