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? about the 400 sb

Discussion in 'The Garage' started by oatsk5, Feb 20, 2005.

  1. oatsk5

    oatsk5 1/2 ton status Premium Member GMOTM Winner

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    So i just bought a 82 that i was told has a 400 in thinkin bout puting a new clutch in it and i have a couple dumb questions as i have never owned a 400 so here they are

    Are the clutchs the same as a 350 /465?
    and if they arent do they usually go for 190 buck range and what are the difs between them any info would be cool just tryin to learn some more in fo you know

    Thanx ervin
     
  2. boz42

    boz42 1/2 ton status GMOTM Winner

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    clutches should be the same. $190 should buy u a good clutch/pressure plate assembly
     
  3. R72K5

    R72K5 Banned

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    remember that 400 was not in 82, so if theres one in it then someone put it in there, if i had a nickle for every time someone called a 305 or 350 in a truck a 400 then id be,......

    never has ended up being a 400 in every instance that the person said it was one,, ever!

    also 400 uses ext balance flywheel, unlike all the other sbc's


    remember that

    good luck
     
  4. goldwing2000

    goldwing2000 Guest

    I have a 400 in my '80 LWB but it's not even the original engine. They did make a 400 in '80 but mine rolled off the line with the Hot Rod 4.1L I-6 :saweet:

    Somebody dropped in a 400 4-bolt and when I ran the numbers, it comes up as being from a '72 Impala.

    The easiest way to identify a 400 vs. any other sb (other than the huge harmonic balancer on the front) is that the 400 has three core plugs (freeze plugs) on each side of the block where the 283-350s only have two.
     
  5. boz42

    boz42 1/2 ton status GMOTM Winner

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    i use to believe this also, but it is not always true. i don't know why but some 400's have 3 some don't. use to think it was only 4 bolts that have the 3 plugs, but i don't think that is true either. i have seen them both ways.:confused:
     
  6. goldwing2000

    goldwing2000 Guest

    Fair enough. I haven't seen a lot of them but all the ones I have seen have 3.
    How about this: If it HAS 3, then it's definitely a 400. If it has 2, then it might or might not be.

    I guess the only way to know for sure is to either run the numbers or pull the heads and check for steam holes between the cylinders.
     
  7. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I was under the imression the later 400's only had 2. My 406 is a later block and has just two plugs.
     
  8. goldwing2000

    goldwing2000 Guest

    Good info. When do you think the cut-off is to be defined as a "later" block?
     
  9. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Good question. :crazy: Say '76-'77? If I had to make a guess I would say '77 was the first year for something different. IIRC after seeing a casting number SBC sheet, there was different casting numbers for '77-80 blocks. THis is VERY rough info though. :crazy:
     
  10. goldwing2000

    goldwing2000 Guest

    That's cool. Learn something new every day. :D
     
  11. mountainexplorer

    mountainexplorer 1/2 ton status

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    Ive owned and seen several SB400's with both 2 and 3 freeze plugs... and they were all 2 bolt mains. Ive heard the same thing before on them, but by personal experience, I havent found any patterns directly related from freeze plug count.

    Also, if you look on either side of the block, there are raised areas that are about 1.5" or so wide that run vertically on sides the block which no other small block has except a 400. I think it was GM's was of trying to make the water jackets a bit larger because of the siamese bore. But thats just a guess. Who knows... all I know is that every SB400 Ive had has had those ridges/raised areas.
     
  12. oatsk5

    oatsk5 1/2 ton status Premium Member GMOTM Winner

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    thanx for the info
     

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