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Identifying 400 vs 350 in '79 Jimmy?

Discussion in 'The Garage' started by wy4tt, Feb 22, 2005.

  1. wy4tt

    wy4tt 1/2 ton status

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    Is there a quick way to tell if a '79 has a 400 or 350? Or do I have to check the numbers? Thanks.
     
  2. SUBFAN

    SUBFAN 1/2 ton status

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    Best check the numbers....


    Second pull the inspection cover and look at the flexplate. Is there a weight welded onto it with drill marks in it for balance?

    Three freeze plugs = 400, although not all 400's have them....
     
  3. supersize75k5

    supersize75k5 OrganDonorRacing.com

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    well I can give you a pic of a t-350 I had loaded


    [​IMG]


    if you want a good reference, go to your local performance shop and look at the tranny pans so you can learn the difference,

    or look on jet's website, they have some decent pics:grin:
     
  4. supersize75k5

    supersize75k5 OrganDonorRacing.com

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    t-400 pan

    [​IMG]
     
  5. supersize75k5

    supersize75k5 OrganDonorRacing.com

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    t-350 pan


    [​IMG]
     
  6. folkenheath

    folkenheath Worthless Trash Premium Member GMOTM Winner

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    Are you talking about engines or transmissions?

    They mentioned stuff about both, I'll add some info about engines.

    - some 400s have 3 freeze plugs, some don't.
    - the engines that don't may or may not have a boss for a 3rd freeze plug that is not drilled.
    - it may have "509" casted in the middle where the freeze plug would be if there isn't any boss casted in
    - all 400s have a large round radius sticking out the side of the block on the #1 cylinder because the bore is larger, you can feel it with your hand
    - the balancer on a 400 has material removed around part of the outer edge because it it externally balanced from the factory.
    - if the heads are off 400s have 2 small steam holes between all of the cylinders that other SBCs don't have.

    Good luck man. :waytogo:
     

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