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v8 350 block strength

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by cocky, Jun 29, 2000.

  1. cocky

    cocky Registered Member

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    I heard that certain years of chevy 350 have a different metal composition that makes them weaker and more prone to cracking. I think it was nickel. Is this true? I am looking for a 350 builder and want to get a good block.

    Also, is there any way to tell if an engine has a 4 bolt main w/o pulling the oil pan?

    Richard
    1970 k5 Blazer
    Don't stand in front of a train naked
     
  2. Burt4x4

    Burt4x4 3/4 ton status

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    They only thing I have ever heard was the blocks that are from Mexico are rumored to have a weaker metal mix, what ever that may be, I think I must have read that somewere??
    as for the 4bolt stuff, dunno??

    Rock ON![​IMG] 72 K5 [​IMG] Led Zeppelin
    http://burt4x4.coloradok5.com
     
  3. James90

    James90 1/2 ton status

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    does the block have some ID # or some thing to tell where it came form

    [​IMG]Go prepared
     
  4. Boss

    Boss 1/2 ton status Author

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    Cocky,

    I remember hearing about that. Something about the brand new 350 crates from GM having a low nickel count or something that when it is running at extreme temperatures, over a long period of time, the block could crack. I don't know though. I got a new crate myself, hope that aint true, but I aint worrying about it though.
    Boss
     
  5. Burt4x4

    Burt4x4 3/4 ton status

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    Ok I now this site has a ton of info it may even be were I read about the Mexico thing http://www.mortec.com/
    Chenck it out and if you can't find the info look for an Email and go from there!!
    Good Luck

    Rock ON![​IMG] 72 K5 [​IMG] Led Zeppelin
    http://burt4x4.coloradok5.com
     
  6. dumbfounded

    dumbfounded 1/2 ton status

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    Well most motors running at extreme temps will have some kind of failure. I had an aerostar van which overheated and had huge cracks on the outside of the block and a cracked head. This is something I wouldn't worry too much about. Not many motors can run extremely hot. Besides your oil breaks down before metal starts doing "strange" things. As for the 350 I've had a few, most people have had a few, and with the amount they produced the chance of you getting a "lemon" is slim to none, just my $.02

    Wasn't me.............
     
  7. 82Jimmy

    82Jimmy 1/2 ton status

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    I heard some crap about aluminum blocks melting when they go over 4000rpms for an extended amount of time (i don't know what he had meant by extended)...Is that true? i heard this from a f*rd repaireman...i know i shouldn't talk to him...but please don't hold it against me! [​IMG]


    Bigger is Better
    Cameron Burnett
    82 Jimmy
     
  8. Bigd

    Bigd 1/2 ton status

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    I seriosly doubt that an aluminum 350 block would melt if run extended time over 4000 rpm.Because any aluminum block would be from a costume manufacture and build for extreme conditions like road racing,drag racing.And why are you listening too a ford guy for anyways.
     
  9. cocky

    cocky Registered Member

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    Thanks for the replies

    Richard
    1970 k5 Blazer
    Don't stand in front of a train naked
     
  10. Blazer1970

    Blazer1970 1/2 ton status

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    Richard, if you have the original 350 that came in your Blazer, it is one of the most desireable starting points for any 350 buildup. They are a 4 bolt high nickel content block, casting number 3970010. Have at it, and build yourself a strong 350, or a stroker.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  11. cocky

    cocky Registered Member

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    Blazer1970, Actually the vehicle that the 350 is going in to is my 1970 landcruiser. So are the seventies blocks the good ones? I'm looking at one out of a 74 El camino.

    Richard
    1970 k5 Blazer
    Don't stand in front of a train naked
     
  12. JimmyDie6.2

    JimmyDie6.2 1/2 ton status

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    3970010 blocks are the best ones. they have the highest nickle content. they came in all kinds of trucks, chevelles, vettes, monte carlos, novas etc..... from like 1968 to 1980
     
  13. cocky

    cocky Registered Member

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    Sorry if this is a dumb question but i can't remember where to find the casting # on the block. Where is it located?

    Richard
    1970 k5 Blazer
    Don't stand in front of a train naked
     
  14. Mike's85K5

    Mike's85K5 Registered Member

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    Casting #'s are on the driver's side of the block towards the back where it bolts up to the bellhousing. About the weak blocks, the Mexican blocks are definitely bad and are easy to ID 'cause they clearly say "Hecto en Mexico" on them. Most truck blocks thru about 1979-80 (and later on 3/4 and 1 tons) were 4-bolt blocks and would be excellent builders.

    Mike
     

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