breaking NEW scat rod bolts??
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breaking NEW scat rod bolts??

  1. #1
    Senior Member rogerroost's Avatar
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    Default breaking NEW scat rod bolts??

    ok guy's,I'm trying to help out a buddy thats not on the forums. he's trying to build his own sbc for his jet boat. He's not stupid ,but he's not an engine builder. he's broken 4 NEW scat (arp) rod bolts. he claims torque spec is 45 pounds,he's breaking them @ 40.says he's using there lube,checked his wrench with another. he has another set of bolts coming,he thinks its a bad batch of bolts . i don't think so .he's got to be doing something wrong. any ideas to help a brother out

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    Resident Ford Nut Sleeper CP's Avatar
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    the bolts are snapping ?

    Not at 45 lbs ft......either a bad trq wrench or bad bolts....


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    Senior Member rogerroost's Avatar
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    that was my reaction too, really snaped at 45 pounds,no way. he's checked the wrench. he thinks bad bolts. but 4 of them?? have the builders seem this before?

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    M and D Performance INCOMPLETE's Avatar
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    Stretch

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    Senior Member snoopjonnyjon's Avatar
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    Did he check there is a big enough chamfer around the top of the bolt hole to clear the radius under the head of the bolt?

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    Senior Member rogerroost's Avatar
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    Quote Originally Posted by snoopjonnyjon View Post
    Did he check there is a big enough chamfer around the top of the bolt hole to clear the radius under the head of the bolt?
    thanks ,I'll suggest that to him. they are scat rods with scat bolts ,but we'll check that out

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    Senior Member ol guy's Avatar
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    Quote Originally Posted by rogerroost View Post
    ok guy's,I'm trying to help out a buddy thats not on the forums. he's trying to build his own sbc for his jet boat. He's not stupid ,but he's not an engine builder. he's broken 4 NEW scat (arp) rod bolts. he claims torque spec is 45 pounds,he's breaking them @ 40.says he's using there lube,checked his wrench with another. he has another set of bolts coming,he thinks its a bad batch of bolts . i don't think so .he's got to be doing something wrong. any ideas to help a brother out
    Okay are they scat bolts or ARP bolts??????

  10. #8
    Senior Member rogerroost's Avatar
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    i was under the impression that arp made the bolts for scat.

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    Senior Member ol guy's Avatar
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    Quote Originally Posted by rogerroost View Post
    i was under the impression that arp made the bolts for scat.
    they very well may and I was not aware of that!!! I will say that the stamping on the bolt looks alot different than the EAGLE rods that my son has. M
    Last edited by ol guy; 04-14-2012 at 04:55 PM. Reason: delete

  12. #10
    Red Blooded American The Doctor's Avatar
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    Without knowing the specifics under which these bolts are failing I would have to ask a few questions:
    * Was anyone measuring stretch? (I saw this already mentioned but saw no response)
    * Was the torque wrench fully operational? (a trained mechanic would surely have known when they were pulling more than 40 lbs.)

    Also, a rod bolt that cannot withstand 40 lbs of torque will never withstand 6000+ RPM. I'm thinking something very wrong is going on. I'd blame the bolts first and question the quality of them and maybe the authenticity of the ARP stamps. Knock-offs come in all industries.
    The best things in life aren't things!

  13. #11
    Senior Member ol guy's Avatar
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    Quote Originally Posted by The Doctor View Post
    Without knowing the specifics under which these bolts are failing I would have to ask a few questions:
    * Was anyone measuring stretch? (I saw this already mentioned but saw no response)
    * Was the torque wrench fully operational? (a trained mechanic would surely have known when they were pulling more than 40 lbs.)

    Also, a rod bolt that cannot withstand 40 lbs of torque will never withstand 6000+ RPM. I'm thinking something very wrong is going on. I'd blame the bolts first and question the quality of them and maybe the authenticity of the ARP stamps. Knock-offs come in all industries.
    I will agree 110%! As I stated the stamping looks alot different than the ones on my sons new eagle h-beam rods! And also the post about how they seat makes alot of sense to me! M reread post 5
    Last edited by ol guy; 04-14-2012 at 05:22 PM. Reason: add on

  14. #12
    Senior Member EVILFORCE's Avatar
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    Operator error. A aluminum bolt would not break at 40 pounds.
    No Fool Like A Old Fool is there?

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    Senior Member rogerroost's Avatar
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    i fully agree. I also thought about the integraty of the bolts performing , a grade 5 bolt from the hardware store should take 40 pounds. i'll make these suggestions to him, lend him my torque wrench.
    how should he measure stretch at this point, and what should he be looking for.

  16. #14
    Senior Member ol guy's Avatar
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    Quote Originally Posted by rogerroost View Post
    i fully agree. I also thought about the integraty of the bolts performing , a grade 5 bolt from the hardware store should take 40 pounds. i'll make these suggestions to him, lend him my torque wrench.
    how should he measure stretch at this point, and what should he be looking for.
    Is the engine at an assemble form and breaking the bolts prior to a final? does he own or know how to use a dial indicator? Not meant to be insulting but is he willing to disassemble the short block to check all this shit out? I would like to see a pic of the rods from a side shot to see how the bolts are seating on the cap. I personally think that bolt stretch is just a few steps away from curing the original problem. M

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