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Opinion on 350 block vs 400 block

Discussion in 'The Garage' started by sjvcon, Feb 25, 2004.

  1. sjvcon

    sjvcon Registered Member

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    I am looking at a few options for engines to replace the tired 350 in my K-20 Sub. I have looked at a bunch of stroker small blocks, some based on the 350 and others on the 400. I have heard of several problems with the 400's -- specifically cracking issues. Any opinions?
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I've got an opinion, 400's rock and can stomp on a 350 when it comes to torque. THere is some cracking issues around the webbing on 4 bolt main blocks but isn't a real big problem. I have a pumped 406 and I am glad I got rid of my POS 350. Just make sure youy have a decent cooling system to keep up with the siemese cylinders in a 400, no big deal, you just need to keep it cool.

    They are great motors that make tons of torque for a small block. /forums/images/graemlins/waytogo.gif
     
  3. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Only issue I seem to have with a 400 is locating one. If I had one I'd run the snot out of it. /forums/images/graemlins/thumb.gif
     
  4. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Yeah, they are getting rare and expensive! I thought you had no problems finding one Tim? And I thought you wen't to bed? /forums/images/graemlins/dunno.gif
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I found one three years ago for $400 that was already .060" over.

    Someone had one on here in IL last summer but I bought my K30 instead. /forums/images/graemlins/thumb.gif
     
  6. 75-K5

    75-K5 3/4 ton status

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    [ QUOTE ]
    Someone had one on here in IL last summer but I bought my K30 instead.

    [/ QUOTE ]

    Hehe, and I bought the engine! /forums/images/graemlins/thumb.gif
     
  7. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    I found one three years ago for $400 that was already .060" over.


    [/ QUOTE ] /forums/images/graemlins/yikes.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/yikes.gif Those walls would be paper thin! That block is junk. .030" is the limit for a DD, .040" is OK for racing but will want to run hot.
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    [ QUOTE ]
    I found one three years ago for $400 that was already .060" over.


    [/ QUOTE ] /forums/images/graemlins/yikes.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/yikes.gif Those walls would be paper thin! That block is junk. .030" is the limit for a DD, .040" is OK for racing but will want to run hot.

    [/ QUOTE ]

    I told him that he would have to pay me to take it. /forums/images/graemlins/rotfl.gif
     
  9. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    As long as your heads have the steam holes (400 heads do other factory heads don't) and you run a real radiator it would be fine to use 400 block. The siamesed cylinder walls can't go out too far on overboring. Use good parts and use the 400 block. And if money wasn't an issue you could buy an aftermarket motown block and not even have to care. /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif
     
  10. SUBFAN

    SUBFAN 1/2 ton status

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    My DD 400 was bored .040....

    If given the choice, I would find a late model roller block and make a 383 out of it....The cheaper roller cam will more than nake up for the 23 cubic inches you lost....

    You can reuse roller lifters, and finding the block with the spider assembly already installed is a cost saver too.

    Do not rev the piss out of the spider web roller block though....
     
  11. CaveBlazin

    CaveBlazin 1/2 ton status Premium Member

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    Hey I got a 400 if someone needs one and its never been bored /forums/images/graemlins/whistling.gif let me know!!!
     
  12. atlantak-5er

    atlantak-5er 1/2 ton status

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    The siamese cylenders tend to make a 400 get hotter than a 350. I have seen some bad arse 400's back when i used to drag race though. Torque!!!!
     
  13. HarryH3

    HarryH3 1 ton status Author

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    I'll gladly trade you a 350 for a 400. /forums/images/graemlins/thumb.gif
     
  14. Jonny-K5

    Jonny-K5 1/2 ton status

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    i'd go with the 350, there is a reason why GM ditched the 400 and kept the 350 alive so long. i've heard the same things as others are saying, 400's are prone to running hot and cant be overbored much due to the siamese bores.
    sure you can build the 400 around its shortcomings, but i think the cons outweigh the pros.
     
  15. Tweetysuarus

    Tweetysuarus 1/2 ton status

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    I had the Stock 400 in my rig with .030 oversize and it would overheat alot during the summer months. I should have kept the crank and built me a 383 stroker! But it's gone so no crying over spilled milk. Stay with 350 and build it up, you'll be happier!
    Bill
     
  16. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    i'd go with the 350, there is a reason why GM ditched the 400 and kept the 350 alive so long. i've heard the same things as others are saying, 400's are prone to running hot and cant be overbored much due to the siamese bores.
    sure you can build the 400 around its shortcomings, but i think the cons outweigh the pros.

    [/ QUOTE ]
    You've obviuosly never had a built 400! /forums/images/graemlins/wink.gif There is no comparison, a 400 will whoop on a 350 when it comes to pulling or keeping big tires turning through deep mud. They make big block style torque and as far as the heating issue, yes they like to get warm because of the block design but there is a reason why almost all 400 equipped trucks came factory with a HD clutch fan and 4 core radiator. The reason why the 400 isn't around any more is because of smog issues mostly from what I heard.
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    The reason why the 400 isn't around any more is because of smog issues mostly from what I heard.

    [/ QUOTE ]

    I'm sure GM wanting to cut costs had NOTHING to do with them eliminating yet another option that customers could have. /forums/images/graemlins/smile.gif

    "Yeah, we had to get rid of the 400 because emissions are so tough...why don't you take this 305 here? We plan on getting rid of the 350 too you know, emissions. 305 is just as good though!" /forums/images/graemlins/rolleyes.gif
     
  18. Z3PR

    Z3PR Banned

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    [ QUOTE ]
    I'll gladly trade you a 350 for a 400. /forums/images/graemlins/thumb.gif

    [/ QUOTE ]I've got a good running virgin (All original) 400cid sbc in my 1976 K5 right now that I'd gladly swap for a 454. /forums/images/graemlins/deal.gif /forums/images/graemlins/waytogo.gif
     
  19. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    [ QUOTE ]
    The reason why the 400 isn't around any more is because of smog issues mostly from what I heard.

    [/ QUOTE ]

    I'm sure GM wanting to cut costs had NOTHING to do with them eliminating yet another option that customers could have. /forums/images/graemlins/smile.gif

    "Yeah, we had to get rid of the 400 because emissions are so tough...why don't you take this 305 here? We plan on getting rid of the 350 too you know, emissions. 305 is just as good though!" /forums/images/graemlins/rolleyes.gif

    [/ QUOTE ]

    Roll your eyes all you want, smaller bore motors do much better with emissions (that's why new trucks have V10s instead of 500 CID V8s). The 305 has a still smaller bore than the 350.

    Might not make sense to you but made perfect sense to the engineers.
     
  20. sjvcon

    sjvcon Registered Member

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    Well now you guys have me all confused. Looks like I opened a real debate. I had thought that except for the steam holes, siamese cylinders and journal sizes, the blocks were essentially the same. Wouldn't a bored over 350 be sort of the same if it had a stroker crank? The 400 that I would be buying would either be Seedomotive's All Forged 414 with 4 Bolt splayed caps, 3.8" forged crank, 6" rods, and a 4.165" Bore or one from Coast Performance in California -- Probably their 421 or 434 shortblock. As for the 350, there seems like a lot of choices. Maybe I should just bite the bullet and go Dart Iron Eagle or Motown (heard Dart is better though)?? Any thoughts on that? /forums/images/graemlins/1zhelp.gif
     

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