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How to tell the difference between a 400 and a 350??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by GM Man, Jan 12, 2003.

  1. GM Man

    GM Man 1/2 ton status

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    Hey everyone, today I bought a 78 GMC Jimmy /forums/images/graemlins/laugh.gif and I was looking at the options sheet in the glove box and it says that my Jimmy came from the factory with a 400. How could I tell if I have a 400 or 350?

    Thanks,
    Travis
     
  2. K5Dan

    K5Dan 1/2 ton status

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    do a search and use this phrase 350vs.400 whats the difference. there is some info there.hope this helps
     
  3. Pure Insanity

    Pure Insanity 1/2 ton status

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    350 has a square pan w/ one corner knocked off at a 45* angle. A 400 likes like a distorted Texas. A square pan is a 700.
     
  4. rodzzilla

    rodzzilla 1/2 ton status

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    400 Will have a counter weight on the flexplate as well as a notch on the harmonic balancer. The 400 will also have either 6 freeze plugs per side on the block, or have the boss cast into the block for the center set.
     
  5. Corey 78K5

    Corey 78K5 1 ton status

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    Engine or transmision?
     
  6. Pure Insanity

    Pure Insanity 1/2 ton status

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    AHHHH I assumed we were talking transmissions. /forums/images/graemlins/ignore.gif Sorry, mine just bit the big one so trannys are on my mind. /forums/images/graemlins/rotfl.gif
     
  7. K5Dan

    K5Dan 1/2 ton status

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    uh! good question /forums/images/graemlins/eek.gif
     
  8. k5ntexas

    k5ntexas 1/2 ton status

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    yeah in his post in the garage i had answered thinkin he was talking about trannies. but i deleted it cuss i think hes talkin bout engine. later.

    jacob
     
  9. K5Dan

    K5Dan 1/2 ton status

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    well now he's got answers for both /forums/images/graemlins/thumb.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     
  10. GM Man

    GM Man 1/2 ton status

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    Yeah thats my fault. What I was asking about was the difference between 400 and 350 motors.

    Thanks.
     
  11. chevyracing

    chevyracing 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    The 400 will also have either 6 freeze plugs per side on the block,

    [/ QUOTE ]


    Try 3 freeze plugs down each side, not 6 on a 400. A 350 only has 2 on each side.

    Look up the numbers on mortec.com....

    John
     
  12. Pure Insanity

    Pure Insanity 1/2 ton status

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    SOME, not many, made it out w/ 2 plugs per side. Most of them are gone from what Ive been told. They were hot w/ the circle track guys since they looked like a 350 at a glance, and they could get the extra cubes. Ive only heard of them but never seen one. I was told about them by a circle track guy that had used them in the past.
     
  13. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    I've heard about the odd freeze plugs too but never seen one either.
     
  14. BigRed89

    BigRed89 1/2 ton status

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    I've got two of them at home. They're great for street racing especially when using a fluid balancer/dampener as it becomes a little more difficult to tell what size it is. /forums/images/graemlins/laugh.gif
     
  15. K5Psycho

    K5Psycho Registered Member

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    well if your talkin about motors you can look up the serial number on the block also if tlking about trans the oil pan is different
     

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