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differences in 305, 307, and 350 blocks

Discussion in 'The Garage' started by dodgedude99, Feb 8, 2006.

  1. dodgedude99

    dodgedude99 1/2 ton status

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    is their any besides just the bore?

    can you take a 305 and bore it to a 350 bore?

    anything else?
     
  2. 1979jimmy350

    1979jimmy350 1/2 ton status

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    yes there are differences the 305 to my knowledge can not be bored to a 350 it does not have enough cylinder wall
     
  3. sweetk30

    sweetk30 professional hooker Premium Member

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    305 is small bore block and 350 crank. 307 just odd stuff. and 350 is best or 3.

    found info: 302= bore of 4.0" and 3.0" stroke
    .............: 305= bore of 3.75" and 3.48" stroke
    .............: 307= bore of 3.875" and 3.25" stroke
    .............: 327= bore of 4.0" and 3.25" stroke
    .............: 350 = bore of 4.0" and 3.48" stroke
    .............: 400 = bore of 4.125 and 3.76" stroke
     
  4. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    307 isn't that odd , just a 327 crank ( large journal ) and a 283 block . They were actually a decent small cube motor with the right heads and pistons .
     
  5. 13lazer

    13lazer 1/2 ton status

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    the cylinder walls are hardened by heat treating, the deeper you go past standard bore the walls get softer and will wear out faster. im running an old 350 block bored to 0.040 over with the 400 crank. so far so good, but i wish i had spent the money on a fresher block. sorry i know that wasn't what you were asking. i just felt like chiming in :k5:
     
  6. dodgedude99

    dodgedude99 1/2 ton status

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    so is there a major difference or not?
     
  7. readymix

    readymix 3/4 ton status

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    yes there is. the blocks are completely different between the 305 and the 350.
    And no you can not bore a 305 out to 350
     
  8. dodgedude99

    dodgedude99 1/2 ton status

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    how are they different or websites to post info from.
    i have an arguement with a friend who says all small blocks (the actual blocks themselves, even though the have different #s)are the same and its just different bores.
     
  9. readymix

    readymix 3/4 ton status

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    If you were to bore a 305 block out to 350 you would be able to look inside the coolant passages. From the outside thay all look identical...even when assembled...except for the balancer on the crank.

    I am not sure of any sites that give specifics for the differances though
     
  10. sweetk30

    sweetk30 professional hooker Premium Member

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    all the extrnal sizes are the same for small blocks. yes the internals are diffrent.
     
  11. JeffHK5

    JeffHK5 1/2 ton status

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    I don't know how true this bit of info is but I've always heard that in the time frame that the 305 was being produced that GM used very low quality materials to reduce cost of the 305 option . The 305 has long been known as having a short life span and low performance levels. I would say that you will be "way" into the water jackets if you try to make a 305 into a 350 unless you where to use a longer stroke crank.

    Sweetk30 shows the basic differences in his bore/stroke chart.

    Now a 11-1 DZ 302 would make a nice woods motor!

    Jeff
     
  12. sweetk30

    sweetk30 professional hooker Premium Member

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    ya sure it would.:rolleyes: :whistle: :xmas:
     
  13. sled_dog

    sled_dog 1 ton status

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    Not going to agree with that at all. The 302 had one place, on the track!
     
  14. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Exactly where it excelled , on a track . Trans Am racing in a ligthened car with short gears , short tires and a close ratio tranny .

    I doubt the lack of low end would be usefull in a truck at all . Low gears with tires under 30 inches , are a lot different than low gears with tires 35 inches and up :D
     

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