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Old 03-29-2012, 06:31 PM   #1
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Default corrillo rod bolt torque setting

anyone have the torque specs for corrillo a-beam rods? stripped today to inspect after an oil pump failure and need to do them up again. engine is a fm short block.
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Old 03-29-2012, 06:40 PM   #2
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The spec depends on which rod bolts you have. Rod bolts don't have a torque spec - they have a stretch spec, which is measured with a rod bolt stretch gauge.

You also need to replace the rod bolts unless you know how much they were stretched upon installation and you measured them before and after removing them to ensure that they haven't permanently deformed. A new set of ARP 2000 bolts is ~$70 IIRC.
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Old 03-29-2012, 06:54 PM   #3
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thanks. need to order an ati damper and a good oil pump anyway so may as well get some new bolts whilst i am at it. any recommendations on where to get all of this?
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Old 03-29-2012, 07:58 PM   #4
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Savington... A bit odd that you say rod bolts do not have a torque spec. Every ARP Rod bolt set I have installed comes with both a torque spec and a stretch spec.

I will agree that ARP recommends using the stretch method over the torque method.
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Old 03-29-2012, 08:45 PM   #5
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I've always read the torque "spec" as an estimation of what the proper preload should be achieved at. The real spec to follow is the stretch spec.
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Old 03-29-2012, 08:59 PM   #6
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That very well could be, And also why ARP says to torque the rod bolt, loosen, torque, loosen and then torque.

But if the ARP engineers thought that the torque method would not work, I think they would have never put it in the instruction sheet to begin with. May have also said to properly fasten the rod bolts a stretch gauge must be used.
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Old 03-30-2012, 12:53 AM   #7
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Originally Posted by BogusSVO View Post
That very well could be, And also why ARP says to torque the rod bolt, loosen, torque, loosen and then torque.

But if the ARP engineers thought that the torque method would not work, I think they would have never put it in the instruction sheet to begin with. May have also said to properly fasten the rod bolts a stretch gauge must be used.
It is stated as a streatch spec with a range of torque that it should take to get to the streatch value. If you reach the streatch value and the torque reqired to get it is low it means the bolt has had too much yield and should be replaced.

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Old 03-30-2012, 08:53 AM   #8
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so should i replace my bolts anyway or can i reuse them? i would not have thought they would have been over stretched by flyin miata when the bottom end was built. would it be really bad if i just reused them ant torqued them just under the max torque spec?
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Old 03-30-2012, 01:12 PM   #9
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so should i replace my bolts anyway or can i reuse them? i would not have thought they would have been over stretched by flyin miata when the bottom end was built. would it be really bad if i just reused them ant torqued them just under the max torque spec?
You need to replace them. Rod bolt failure is a catastrophic event that will likely require a complete motor replacement.
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Old 03-30-2012, 02:15 PM   #10
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yea your rite. ordering a damper and an oil pump today so may as well order some bolts too. going to make a stretch gauge tomorrow on the milling machine i think. got a brand new dial gauge sitting doing nothing. looks pretty simple to make.
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