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4 Bolt main vs 2 Bolt

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Nicks 72, Mar 11, 2005.

  1. Nicks 72

    Nicks 72 Registered Member

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    I had a question because I am in a little bind for time. I need a short block for my 87 tbi motor. The one I was going to use I just found out needs to be bored. I need to finish this truck real soon.
    What I am thinking of doing is using a 330 horse crate motor I have saved up for my 72 but just using the short block from this and putting on all the TBI heads manifolds and stuff and holding on to my 330 vortec heads and manifold for later. Then I was going to rebuild the old TBI motor and re install the vortec heads etc to get back where I was with the 330 horse..
    One of my delimas is that the K motor(TBI) is a 2 bolt main and the 330 horse is a 4 bolt main. Will I be screwing myself in strength if I try and make this 2 bolt into a 330 horse motor. Any other ideas about doing this?
    I need to make up my mind today. Thanx Guys... Nick
     
  2. TWISTEDJACK

    TWISTEDJACK 1/2 ton status GMOTM Winner

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    Two bolt will be plenty strong.
     
  3. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    2 bolt blocks will live in a truck , hell in a street/strip car too . Just use quality ARP bolts/studs .

    4 bolt mains are for high horsepower and endurance , overkill for most apps . Of course we alll want 4 bolt mains , but if you have a good 2 bolt block use it .

    And if you wanted you could always machine the 2 bolt block for 4 bolt mains or splayed 4 bolt mains , but thats money and I can't see the use in a truck justifying the cost :k5: :k5:
     
  4. smalltruckbigcid

    smalltruckbigcid 1/2 ton status

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    2 bolt will work fine just check to make sure that all the sensors will mount into the other block (if you are using the tbi)
     
  5. imiceman44

    imiceman44 1 ton status

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    The 2bolt will be fine up to 400HP, if you want more then splayed caps are far better than regular 4 boltmain caps so if you ever need that much power it would be justified.
    The 2 bolt main block is actually more reliable because it doesn't have the extra weekening holes.
    :grin:
     
  6. blazinzuk

    blazinzuk Buzzbox voodoo Premium Member GMOTM Winner

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    Also a 4 bolt will hold up to higher rpms and power adders (nitrious blowers etc.) better.
     

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