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2 or 4 bolt? that is the question.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Jmask, Feb 25, 2002.

  1. Jmask

    Jmask Registered Member

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    What is your opinion on the subject? I have had more people go crazy over a 4 bolt SBC 350 just cause. No one has ever given a real reasonable reason, just thought 2 extra bolts an the 2,3,and 4 mains meant better strength. I detonated a piston on a crate 350 going up Mount Ashland in Or last Sept that only had 10000 miles on her and she was running at 210 degrees and strong Oil press. And for no reason, I threw 2 rods exploded the no 2 piston and assoc valves, shattered the cam sprocket and chain, shot so many holes in my pan it looked like swiss cheese, and had 4 pieaces of camshaft in the block not to mention the 4 3 inch pieces of piston, half a conn rod(MELTED!?) and the millions of bits of shrapnel everywhere. Lets hear if anyone else has any hooror stories out there.
    Al
     
  2. Stomp

    Stomp 1/2 ton status

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    I was always told 4 bolts handle high rpm better than 2 bolts.

    <a target="_blank" href=http://www.geocities.com/custar/index.html>Your parents WANT you click here, NOW!!</a>
     
  3. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    only engine i have ever blown is a 4 baner i my datsun and my 6 cyl in my chevelle. means to put a 383 in it i might add.

    4 bolts handle RPM and tourque a lot better, but a splayed 4 bolt(machined 2 bolt) handle it even better. if you are building a mild engine you should be just fine ether way. but a powerhouse it is better to go with 4 bolts
    this i have been told by all the machine shops round here. i have been debating which one of my block to machine first.
    then i decided to sell the 2 bolt, since i am moving and need as little as possible to move.
    Grant
    Grant

    take me drunk, i am home
    www.geocities.com/seventy4blazer/parts4sale.html
     
  4. LKJR

    LKJR 1/2 ton status

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    for everyday applications it dosen't make 2 bits of difference, I know of several race teams that run the 2 bolt blocks without a problem. They can handle up to like 600hp w/o a worry. the 4 bolt is supposed to be stronger, but I think the issue is overrated, unless your running a 1200hp dragster doing 4 second quarter miles. just my .02

    Like em big and topless
    You call THAT...a 4x4....LMAO?
     
  5. Jmask

    Jmask Registered Member

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    In my experience with chevy's, the debate over 2 to 4 bolt is highly overrated. The fact that you have less surface area underneath the motor from caps 2-4 doesn't help one bit. The 4 bolt puts most of the torque towards the center of the crank as opposed to evenly as in the 2 bolt, However tests have shown that the 4 bolt can handle it, but then again so can the 2 bolt. Bob Castle, owner of Castle Empire Machining in Longview, Wa will attest to this. I, being the sceptic that I am, have checked this out in several racing, and hi performance articles. In retrospect, while the 4 bolt seems appealing, it is only my opinion that you won't get more durability or strength with a 4 bolt. I don't recall if Mopar or Ford have 4bolt engines, do they?
     
  6. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Super Chevy asked an engine builder and they were told 2 bolts could safely handle up to 650 HP.

    Red 1989 GMC Suburban SLE V1500 - TBI 350, 700R4 w/ shift kit, Quad-shock front, 31/10.50/15 Pro Comp MT, 4.10 gears, Duals off cat
     
  7. Zepplin

    Zepplin 1/2 ton status

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    I have a 496 with 2 bolt mains. I won't see anything over 600hp but, if you are worried just ditch the bolts and go with studs. I went with studs and I won't even worry about them holding up. A engine builder told me that by switching to studs you are doubling the strength as compared to bolts.

    Just stud it and forget it!

    74 Blazer
    Zepplin
    Check out my Blazer
    <a target="_blank" href=http://coloradok5.com/gallery/albup14>http://coloradok5.com/gallery/albup14</a>
     
  8. Stomp

    Stomp 1/2 ton status

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    A 496??? Is that a bored 454???

    <a target="_blank" href=http://www.geocities.com/custar/index.html>Your parents WANT you click here, NOW!!</a>
     
  9. Jaden

    Jaden Registered Member

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    Yeah I got a 4 bolt 350 with a nice big crack in it for ya... I have been told the 4 bolt is only better with big nitrous or huge rpm.. otherwise its the same. BTW why do chevys crack in the lifter valley 2bolt/4bolt.
     
  10. POWERMAD

    POWERMAD 1/2 ton status

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    Bored and stroked. .060 over pistons and a 4.250" stroke crank.

    <font color=green> Too bad ignorance isn't painful </font color=green>
     
  11. TX Mudder

    TX Mudder 1/2 ton status

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    I agree that 4-bolt blocks are over-rated. Yes, they should be able to handle more power. But 2 bolt blocks should be fine unless you are making 400+ HP at the least.
    That being said, I would choose a 4-bolt over a 2-bolt if everything else was equal.
    I had both a 2-bolt and 4-bolt block in my garage. I built the 2-bolt to basically stock config and have it in my chevy now. The 4-bolt is still on the engine stand waiting for it's 383 crank.
    -- Mike

    See <font color=orange> Project Old Orange! </font color=orange><a target="_blank" href=http://users3.ev1.net/~mattell/>CLICK</a>
     
  12. Zepplin

    Zepplin 1/2 ton status

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    Powermad wins the prize!!

    74 Blazer
    Zepplin
    Check out my Blazer
    <a target="_blank" href=http://coloradok5.com/gallery/albup14>http://coloradok5.com/gallery/albup14</a>
     

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