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what size are ARP nuts

Discussion in 'Engine Building' started by GSRCRXsi, Oct 12, 2005.

  1. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    i have the 9mm ARP rod bolts for b18c1 engines. i figured it was metric, but i guess it isnt. 11mm was a little lose, and 10 mm didnt fit.

    is it 3/8" or something?
     
  2. pissedoffsol

    pissedoffsol RETIRED

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    yeah, arp uses SAE tools.

    3/8" is smaller than 10mm.

    7/16" is a hair bigger than 11mm

    remember, they need to be stretched too....
     
  3. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    they dont HAVE to be stretched, but its the best way to do it. arp recommends istalling it that way, but they say you can get away with their torquing procedure if you dont have a stretch guage (something like torque to 40ft-lbs 3 times). plenty of other people have done it that way with no problems. B16 has these and did it that way.

    and on the size, i dunno what it is.

    edit, my bad, 7/16" is a hair bigger. at 11.1mm, [geek] i was multiplying by 24.5 instaed of 25.4 [/geek] [​IMG]

    so im inbetween 10mm and 11mm, whats inbetween that in sae? i cant imagine they would make these out to 32nds. 13/32" is 10.3mm so [​IMG]
     
  4. pissedoffsol

    pissedoffsol RETIRED

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    tbone blew up a motor becuase of those rod bolts. get them stretched. seriously.
     
  5. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    youre sure it was because of the rod bolts? and im sure his motor is a little more intense them mine will be, lol.

    and im just making sure we are talking about the same thing with stretching. you are making it sound like you have to take the bolts somewhere to be stretched, then installed. im talking about stretching them to a certain length when you install the rod (well not a certain length, but a certain amount of stretch beyond each bolts length), and measuring the stretch with a stretch guage, rather then torqing them down.
     
  6. pissedoffsol

    pissedoffsol RETIRED

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    send him a pm-- hes TBone on h-t
     
  7. B16

    B16 Super Moderator VIP

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    I didn't get them streched, I did it the other way like Ian said. I have had 0 problems. Maybe something else happened? [​IMG]
     
  8. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    i talked to tbone, and what happened to his rod bolts was the machine shops fault.

    as most people know, when you install new rod bolts, 9 times out of 10 it deforms the rod bore and you have to have them resized. well to resize them the machine shop removes material from end cap then torques (or stretches, whichever you want them to do) the end cap back on to spec to rebore the hole to the correct size and make it perfectly round again. now what happened in Tbones case was the machine shop overstretched the bolts, permanently deforming them making them skinnier. he said he was able to turn the rod upside down with the end caps removed and the rod bolts would just fall out since they were now skinnier. this was purely the shops fault and has nothing to do with the method (torquing or stretching) in which they were installed in the motor.

    but since stretching is more accurate, i will mostlikely be picking up a stretch guage and installing them that way.
     
  9. MikeBergy

    MikeBergy Blah blah blah....

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    You worry me. I torqued them the way the ARP sheet told me to. Used the arp moly lube, then torqued in a two step sequence to the correct spec, then loosened, and then retorqued. I think I did it like 5 times, just to be on the safe side. But then again, my rod bolts came with the rods I purchased, so I hope I don't have any problems.
    (fingerscrossed)
     
  10. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    i wouldnt worry too much
     
  11. DelSlo

    DelSlo Senior Member

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    I JUST installed ARP head studs on my b16, just got the custome studs made for the b- series. and all it said was hand tighten the studs into the block and then use the lube . and for an aluminum head torque the nuts to 65ft lbs and call it a day! thats what i did. i just put reassembled the head today and now its back on the car!
     
  12. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    ok, good job.

    that in NO way helps. this thread is about ARP rod bolts, not head studs. nor do i need torue specs, i need the nut size.

    but to add some value here, someone on h-t said they were 7/16 12pt. anyone confirm this?
     
  13. DelSlo

    DelSlo Senior Member

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    holy crap! haha im sorry dude i just did the head studs this afternoon so my mind was still in head stud mode! haah as soon as i read ARP i just must have assumed it said head stud! haha completely my bad!! :cry2:
     
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