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identify 400 small block chevy

Discussion in 'The Hokey Ass Message Board' started by billjharris, Dec 31, 2008.

  1. billjharris
    Joined: Oct 7, 2005
    Posts: 861

    billjharris
    Member

    anyone know of a simple, quick way to identify a 400 small block vs 350 small block chevy?
     
  2. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,859

    JohnEvans
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    from Phoenix AZ

    Normally 3 freeze pulgs per side, also crank balancer has a releaved area on the OD [externally ballanced]
     
  3. Tony
    Joined: Dec 3, 2002
    Posts: 6,762

    Tony
    ALLIANCE MEMBER

    3 freeze plugs of the side of the block rather than 2.
     
  4. primed34
    Joined: Feb 3, 2007
    Posts: 542

    primed34
    Member

    If you are talking about bare blocks, the 400 has steam ports between the cyclinders.
     
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  5. Bellytanker
    Joined: Aug 18, 2007
    Posts: 113

    Bellytanker
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    from California

    The freeze plugs don't identify a 400 vs 350, if a 400 has only two freeze plugs on the side of the block it's a two bolt main, if there are three plugs on the 400, it's a four bolt main. The above identifiers are correct, the larger, relieved harmonic balancer, and the steam holes are giveaways. If you can see the flex plate, the 400 has weights on it, again for external balancing.
     
  6. Tony
    Joined: Dec 3, 2002
    Posts: 6,762

    Tony
    ALLIANCE MEMBER

    I stand corrected..
    There's a bit of info i didn't know, and i've built or had my hand in a bunch of them..
    It was a long time ago, but evidently, they must have been 4 bolt blocks.
    I've learned something :)
     
  7. budd
    Joined: Oct 31, 2006
    Posts: 3,471

    budd
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    the harmonic balancers are different, the 400 has a section removed as it is externaly balanced.
     

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  8. Groucho
    Joined: Dec 22, 2002
    Posts: 11,520

    Groucho
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    But, I "think" the 2 freeze plug 400's have a cast area for the 3rd freeze plug that's not drilled for that freeze plug. So, you can still I.D. it as some sort of 400.
     
  9. k9racer
    Joined: Jan 20, 2003
    Posts: 2,533

    k9racer
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    cast no ending with 509 both 2 and 4 bolt, 511 , 817 and the last is 609 I think . These engines are externaly ballanced, if apart larger mains steam holes in the deck, The cyl are wedged together as in siamise {sp} no water flows between the cyls. Bore size of 4.125 . If in doubt try the web site MORTEC. I hope this helps... Bobby..
     
  10. Fogger
    Joined: Aug 18, 2007
    Posts: 1,190

    Fogger
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    Groucho is correct. I have a 400 small block with 2 freeze plugs on each side and a cast area between them that was not machined. Indicates a 2 bolt main which many engine builders consider stronger. Also as mentioned the steam holes on the block deck. The FOGGER
     
  11. Thumper
    Joined: Mar 7, 2005
    Posts: 1,603

    Thumper
    Member

    Also look at the rear crankshaft flange....it will have a dowel pin sticking out to locate the flywheel .
     
  12. Groucho
    Joined: Dec 22, 2002
    Posts: 11,520

    Groucho
    Member

    Yes, some like the 2 bolt 400 blocks better, claiming the outer bolts on the 4 bolt 400 block go into a thinner area of the block than other small blocks. If 4 bolt's desired, splayed main caps are recommended
     
  13. jimmyv
    Joined: Dec 1, 2006
    Posts: 620

    jimmyv
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    I have had several 2 bolt main 400's with 3 freeze plugs per side.
     
  14. Drive Em
    Joined: Aug 25, 2006
    Posts: 1,742

    Drive Em
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    I have only seen the 511 block with 4 bolt mains, though they can also be 2 bolts. Every 509 and 817 block has been a 2 bolt main block, and I have seen hundreds. I have a buddy that has been collecting them for about 20 years and he has hundreds and hundreds of them.
     
  15. Bellytanker
    Joined: Aug 18, 2007
    Posts: 113

    Bellytanker
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    from California

    I got my first 400/4 bolt in 1980 and at that time was told about the 2 or 3 freeze plug identifier, sorry if it's incorrect. :confused:
     
  16. Groucho
    Joined: Dec 22, 2002
    Posts: 11,520

    Groucho
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    WHY?:confused:
     
  17. Drive Em
    Joined: Aug 25, 2006
    Posts: 1,742

    Drive Em
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    He, his wife and son all circle track race, so he uses some of them, but he'll never use them all. He also has hundreds of Muncie and Super T-10 4 speeds, he runs and add in the local newspaper saying that he wants aluminum 4 speeds, he pays $50.00 for them and not a nickel more.
     
  18. Groucho
    Joined: Dec 22, 2002
    Posts: 11,520

    Groucho
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    WOW, I wonder if that'll work for me? Wanted-aluminum 4-speeds, will only pay $50. I wonder if I too will get hundreds of em?:D. I think I'll start that Ad right now in the HAMB want Ads. Hope your friend's not already advertising there:(
     
  19. k9racer
    Joined: Jan 20, 2003
    Posts: 2,533

    k9racer
    Member

    whoa I would like to get some of those texas deals. The last 3 400's I got possession of came from cars that were running and driving. All Impalas after I pulled engines Ithen sold the rest of the car to derby guys. Last month a fellow I have known for many years came by my shop selling some transmissions. I got 2 muncie 4 speed, a ford t10 . a saginaw 4 speed and 4 muncie 3 speeds all for 1500 dollars and I felt like I took advantage of his bad luck. All of them around here have been used up or being hoarded by restorers... If anybody within 3oo miles of huntsville alabama has any 400's Chevys that is. I am very intersted in buying them. Thank You.. Bobby..
     
    Last edited: Jan 1, 2009
  20. Curly
    Joined: Jun 26, 2003
    Posts: 1,148

    Curly
    Member

    I have a real oddball then....two freezeplugs and only two freeze plug "bulges" from what my memory tells me (Motor is at the machine shop now). I ground off the casting number on the side of the block to hide the fact that it was a 400. It took a while to find a good 2 plug block to build as the bottom end had to be stout.

    I semi-filled the block (up to the freezeplugs), studded and clearanced the oilpan rail for H-beam rods and an aftermarket crank before I sent it to the shop and only remember two cast areas for a freezeplugs and both had freezeplugs in them????

    And yes the bore is WAY bigger than a 302/327/350 4" I just wanted the two plug motor so I could tell people it was an "old school 327" that runs real good:cool:
     
  21. JRODHOTROD
    Joined: Mar 23, 2006
    Posts: 442

    JRODHOTROD
    Member
    from Manor, TX

    count all the teeth on the flexplate you should have 168 of them.
     
  22. Engine Pro 5X
    Joined: Feb 13, 2008
    Posts: 4,186

    Engine Pro 5X
    Member

    ----#$#$ If he circle track races 400 blocks he'll use them all as it's just a matter of time >>>>.
     
  23. Shifty Shifterton
    Joined: Oct 1, 2006
    Posts: 4,972

    Shifty Shifterton
    Member

    This is a "509" 2 bolt block, it's twin freeze plug layout is how all my 400 2 bolts have been.

    Honestly, having taken apart a shitload of mid 70s/80s small blocks over the years, you can't trust casting codes or freeze plugs 100% to identify 4 bolt blocks. All the indicators are 90% reliable at best. Not just 400s, but also 350s. Only way to really know is seeing firsthand. Thus really wouldn't suprise me if 400s exist that have 3 freeze plug bosses, but only 2 drilled.

    [​IMG]
     
    Last edited: Jan 1, 2009
  24. tomslik
    Joined: Mar 3, 2001
    Posts: 2,171

    tomslik
    Member

    yours is the FIRST 400 that i've ever seen that was a 2 frost plug block WITHOUT the bosses....
    learn sumthin' new every day.....
     
  25. tomslik
    Joined: Mar 3, 2001
    Posts: 2,171

    tomslik
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    what'll THAT tell ya?
     
  26. 50mercfan
    Joined: Nov 5, 2003
    Posts: 2,201

    50mercfan
    Member

    when i was dirt tracking a few years ago this is what i understood. 4 bolt 400's where 1968 only. we wouldn't touch them. the outiside bolts in the main cap actually protruded into the bottom of the cylinder. we always bought 2 bolt blocks, used aftermarket splayed main caps and had the block drilled to match. then everybody went aluminum and we all had a shit load of 400 cubic inch boat anchors sitting every where.
     
  27. 50mercfan
    Joined: Nov 5, 2003
    Posts: 2,201

    50mercfan
    Member

    your right most of the time. but, not all the time. i had a 421, a 427 and a 454. all built from stock 400 blocks. turned them all 8250 rpms. never had a major engine failure.
     
  28. tomslik
    Joined: Mar 3, 2001
    Posts: 2,171

    tomslik
    Member



    i'll take those anchors for scrap price!
    especially the 68-69 400's ;)
     
  29. randydupree
    Joined: May 19, 2005
    Posts: 606

    randydupree
    Member
    from archer fl

    correct.
     
  30. Groucho
    Joined: Dec 22, 2002
    Posts: 11,520

    Groucho
    Member

    ME TOO! That's why I said I "think" they have a boss for the 3rd plug:cool:

    No 400's in 1968. 70 was the 1st year I believe. NOT any sooner
     

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