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305 to 350

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by FL84K5, Dec 24, 2001.

  1. FL84K5

    FL84K5 1/2 ton status

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    What all is involved in swappin a 305 to a 350? Will I need a new flywheel? Will the engine mounts from the 305 work? Do all the accessory brackets like the air and power steering bolt up? Thanks
     
  2. HarryH3

    HarryH3 1 ton status Author

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    Remove the 305 and replace it with the 350. It's just that easy. All the external dimensions are the same and they're both internally balanced engines. So your accessories will bolt right onto the 350, as will the flywheel, at least if they are both 2-piece rear main seal engines. If the 350 is one of the newer one-piece rear main seal engines, then you'll need a flywheel with the correct bolt pattern to match up with it.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  3. Pure Insanity

    Pure Insanity 1/2 ton status

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    Spend the extra couple of bucks and replace the mounts while it out. They are alot easier to do now than later. And any other "disposeables" like water pump, fuel pump and such.

    If ya can't stop.......Smile as you go under! [​IMG]
    PIC of mine from flblazers site<a target="_blank" href=http://www.flblazer.alloffroad.com/photo3.html>
    GO</a>
     
  4. SCOOBYDANNN

    SCOOBYDANNN 1/2 ton status

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    Need to get a new Harmonic Balancer also

    Sun Desert Offroad <a target="_blank" href=http://4x4.alloffroad.com>4x4.alloffroad.com</a>

    It's all fun and games till someone loses an eye!
     
  5. HarryH3

    HarryH3 1 ton status Author

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    Why a different harmonic balancer? They're both internally balanced engines. Summit lists the same harmonic balancer for 265's to 350's. The 400 is the only small block that I know of that needs a different balancer, since it's an externally balanced engine. Is there something special about the 305?

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  6. Pure Insanity

    Pure Insanity 1/2 ton status

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    A different balancer because it falls into the disposables catagory. Easier to replace on a stand than in the frame.

    If ya can't stop.......Smile as you go under! [​IMG]
    PIC of mine from flblazers site<a target="_blank" href=http://www.flblazer.alloffroad.com/photo3.html>
    GO</a>
     
  7. k5king

    k5king 1/2 ton status

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    look at one of a 305 and one from a 350,,they are different ! the 350 one is much thicker and heavier,and i do believe even though they are internally balanced,,the balancing is different also,,therefore you cannot use the flywheel from a 305 on a 350 i believe,the weight's are in a different spot on the flywheel,from what i understand.i dunno how exact this is but i do know there is a difference in them.


    <font color=purple>ANYBODY LOSE THEIR JEEP????????[​IMG]
    I JUST FOUND ONE UNDER MY BLAZER!!!![​IMG]
    [​IMG][​IMG]</font color=green>
     
  8. HarryH3

    HarryH3 1 ton status Author

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    But that's the whole point. There shouldn't be any weights on the flywheel. That's the meaning of the term "internally balanced". An internally balanced engine doesn't require any weights on the flywheel or balancer because the crank and rotating assembly are already balanced. There may be some VERY small weights and/or holes drilled in the flywheel or balancer themselves, but that's just to make sure that those parts are perfectly neutral balanced, so that they don't throw off the balance of the internal parts.

    Do 305's require external balancing? If so, that's a new one on me. The only externally balanced small block Chevy that I know of is the 400. But then, I've never played with 305's either. Any time I was K5 shopping, I was all done looking when I saw there was a 305 under the hood. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     

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