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How do I tell if my new burb has a 400 in it or a 350?

Discussion in 'The Garage' started by Topdown, Jan 29, 2004.

  1. Topdown

    Topdown 1/2 ton status

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    Its bone-ass stock, still has the heat tube from the exhaust manifold to the air-filter... the sticker on the air filter says that its a 400ci engine. However, I want to know for sure... how do I tell?

    Is do I have to check casting numbers? If so, what numbers will indicate that its a 400? Is the block color an indicator?

    Thanks
    -Ryan
     
  2. Cmoe

    Cmoe 1/2 ton status

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    What year is the Burb?
     
  3. 55Willy

    55Willy 3/4 ton status

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    easist way to tell is to crawl under it,the 400's had a 3rd freeze plug on the sides, there may not be a 3rd but there is still a casting boss for it. also the balancer would be cut for balance, since the 400 is externaly balanced. /forums/images/graemlins/peace.gif
     
  4. Topdown

    Topdown 1/2 ton status

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  5. Topdown

    Topdown 1/2 ton status

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    Hmm... Thanks!
     
  6. Beast388

    Beast388 1/2 ton status

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    [ QUOTE ]
    easist way to tell is to crawl under it,the 400's had a 3rd freeze plug on the sides, there may not be a 3rd but there is still a casting boss for it. also the balancer would be cut for balance, since the 400 is externaly balanced. /forums/images/graemlins/peace.gif

    [/ QUOTE ]

    Checking for the 3rd freeze and/or boss is a good idea, but not all 400 had the middle boss. I would still check, because if you see it, then it is a 400. If it is not there, then it still may be a 400.

    Like Jeremy said, look for the unique balancer and also check the flywheel/flexplate(if you can see it). The 400 flexplates will have a weight(s) welded to it.

    Post up the casting numbers on the back of the block and the stamped number on the block in front of the pass. side cyl. head. Someone can decifer it for you. /forums/images/graemlins/waytogo.gif
     
  7. BurbinOR

    BurbinOR 3/4 ton status

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    In addition to what Beast388 said, look for the numbers 509 cast into the block on the bottom sides..........both the 400's I ran had that feature.

    Does your 78 have original sticker under the hood on the radiator cover? /forums/images/graemlins/laugh.gif Not that it would mean what you have NOW is a 400 but might tell you if it had one factory.
     
  8. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    Checking for the 3rd freeze and/or boss is a good idea, but not all 400 had the middle boss. I would still check, because if you see it, then it is a 400. If it is not there, then it still may be a 400.


    [/ QUOTE ]I have exactly what beast is talking about...I don't have three feeze plugs but it is a 400. Like BurbinOR said look for 509 as the (i think) last three digits on the block. Mine had a 6 or 7 digit number on the bellhousing next to the dist and ended with 509. I think(not sure) that I have a later 400 because of the lack of a 3rd freeze plug. Yours might be just like mine since it's a 78'. /forums/images/graemlins/waytogo.gif
     
  9. leadfoot067

    leadfoot067 1/2 ton status

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    511 was also a 400...i have a casting number book...get the number at the back drivers side of the block...on the bellhousing flange just down from the drivers side head...
     
  10. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I think the 511 400's were the earlier 70-73 4 bolt mains. Right?
     
  11. K1Orion

    K1Orion 1/2 ton status

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    Just look at the balancer. It will have what looks like a chunk missing from part of its perimeter. All factory 400s are externally balanced and will have this kind of balancer. I'd link to a pic but couldn't find 1. I didn't look too hard though. /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif
     

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