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400 Motor Questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by SummitXMK, Dec 17, 2001.

  1. SummitXMK

    SummitXMK 1/2 ton status

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    Will there be any differences in a motor from a 81 k30 and my 78 Blazer? They are both 400 sbc motors.

    78 K5 Cheyenne 400 th350 203 stock nuthin' special (YET)
     
  2. Andreas

    Andreas 1/2 ton status

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    If you´re absolutley sure they´re both Chevy 400 smallblocks then there will no difference. FYI, the 400 in that K30 is a swap-in. GM didn´t make the sbc400 in 81.

    Andreas

    406cui of pure sh*t[​IMG]
     
  3. zakk

    zakk 1/2 ton status

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    a k30 should have a 454 BB, i think

    -zakk

    '77 1-Ton K5

    [​IMG] CK5's MOAB 2002 OR BUST!! [​IMG]
     
  4. Sparky87k5

    Sparky87k5 1/2 ton status

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    K30's can have either SBC or BBC's in 350 or 454 cubic inches. Don't think 400's available in 81.

    87 K5, 427BBC,D60 & 14BFF, NV4500, NP208, TSM disc's,
     
  5. TorkDSR

    TorkDSR 1/2 ton status

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    there is a possibility that the older 400 has the 2 bolt main bearings. which seems to be much more desirable.

    Tork DSR
    "look ma, i can make the dog pee white...."
    aol screen name TorkDSR
    <a target="_blank" href=http://www.torkpig.homestead.com>http://www.torkpig.homestead.com</a>
     
  6. mudddog91

    mudddog91 1/2 ton status

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    If my memory is correct all small block 400's are 2 bolt mains!
     
  7. 1bad82k5

    1bad82k5 1/2 ton status

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    Actually a few of them were four bolt mains. I have on sitting in my shop, but i am not going to use it. The four bolt main 400's are actually weaker than the two bolts.
    eric

    Don't get me started, you know how i get.
    82k5, 14bff, d44, sm465, np205, 300hp350, rust
     
  8. TX Mudder

    TX Mudder 1/2 ton status

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    Some 400 WERE 4-bolt mains, but they are considered weaker due to the amount of material removed to make room for the four-bolt cap. The web is weaker.
    2-bolts are better for 400's.
    -- Mike

    <font color=blue> Married to a woman who understands the need for <font color=orange>Hugger Orange. [​IMG] <font color=blue>
     
  9. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    70 through 72 400 small blocks were all 4 bolt main motors. There is no discernable difference in bottom end strength between the two. I have seen over 700 HP on nitrous out of both blocks with no main cap failure. The factory crank is the weak link but only if you are talking over 500 HP. A stock 400 bottom end built correctly to produce low end torque will not have any failures due to weakness. My $.02.

    '85 K5 : Run it til it breaks, then fix it and go again!
     
  10. mudddog91

    mudddog91 1/2 ton status

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    I got into my trusty chevy engine book and I was thinking of the 327.Sorry for the confusion.
     
  11. SummitXMK

    SummitXMK 1/2 ton status

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    Thanks alot guys that was way more than I needed. That was great!!!!

    78 K5 Cheyenne 400 th350 203 stock nuthin' special (YET)
     
  12. ricka

    ricka Registered Member

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    But most of the four bolt mains did have steel cranks, which are desirable.
    Also, 400ci's weren't available stock in 1981. I think it was 1974-1979
    or some range of five years.

    -------
    Rick Anderson (rick.d.anderson@tektronix.com)
    Tektronix, Inc. Beaverton, OR 503-627-2630
     
  13. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    If you are referring to forged steel cranks, Chevrolet never made a forged steel crank for the 400. They were all cast nodular iron. The 400 small block production run was from '70 through '79.

    '85 K5 : Run it til it breaks, then fix it and go again!
     

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