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350 or 400 block ?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by wheelin247, Apr 4, 2001.

  1. wheelin247

    wheelin247 1/2 ton status

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    i just recently pickup up a parts truck and i was wonderin if the engine in it was a 350 or a 400 how can i tell ?
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    check out the Chev ID links on my page listed below.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  3. weisel

    weisel 1/2 ton status

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    I dont know from outside the engine, but if you take off a head, the 400 has a 4"+ bore, and the 350 has a 4 inch bore.

    Insurred by Smith & Wesson
     
  4. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    400 has a 4.125" bore. 350 is 4.000" bore. Otherwise try to follow casting numbers, this is the best idea. Also, the freeze plugs are placed slightly different.

    <font color=red> Check out my rig @ </font color=red>
    <A target="_blank" HREF=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</A> [​IMG]
    <font color=red> I Love My Blazer! </font color=red>
     
  5. Wheels

    Wheels 1/2 ton status

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    2 freeze plugs or 3 freeze plugs on the side of the block?? Two freeze plugs it should be a 350, 327, 305 and 3 freeze plugs it's a 400. This is a quick way, best way is to get the cast number and check it out against a good source.
     
  6. Triaged

    Triaged 1/2 ton status

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    I had to check the same thing on my truck. First look at the harmonic ballancer. If it has a big notch on part of it than you have a 400 crank (the 400 SBC is externally ballanced) if it is smooth all around than it is a 350 crank. You may have a stroker motor (a 383 with a 350 block and a 400 crank). Next the block. 350 blocks have 2 freeze plugs on each side. 400 blocks have 3 or 2 plus a raised area where there looks like a freeze plug would be.

    '71 Blazer CST with alot of rust
     
  7. 89Blazin

    89Blazin 1/2 ton status

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    The freeze plugs was good info. The 400SB has a 4.125 bore...same as a 400 BB. They are 6.6 liter engines...same as the 396. Got a 400SB with double hump heads in my 85 burb. Love it with the TH400.

    85 Burb and an 89 Blazer
    One just for fun, one simply for pleazer
     
  8. Pure Insanity

    Pure Insanity 1/2 ton status

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    ive heard of a rare block that is a pretty hot item the freeze plugs way of id dont work it looks like a 350.i guess roundy round guys scarffed em up to build a 400 instead of 350 they get away w/ it as long as they dont get torn down,it was a circle track guy that told me this i havent got a clue to the validity of it.it may be an urban legend.hahaha!

    PURE INSANITY
    86 blazer silverado 400 horse 350 w/vortec heads 38 x15.5 swampers (40 hawgs next)10 bolts(blah)w/4:88s coming soon,14 bolt.
     
  9. 89Blazin

    89Blazin 1/2 ton status

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    Purinsanity....you're right....the racers love em. A part store near Kansas City will trade $200 in new parts for good 400SB cores.

    85 Burb and an 89 Blazer
    One just for fun, one simply for pleazer
     
  10. Pure Insanity

    Pure Insanity 1/2 ton status

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    heh what do ya know!i really thot it was b/s but figured id post it anyway in case it was true.so maybe there is really a jackalope!!hahaha!

    PURE INSANITY
    86 blazer silverado 400 horse 350 w/vortec heads 38 x15.5 swampers (40 hawgs next)10 bolts(blah)w/4:88s coming soon,14 bolt.
     

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