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Discussion Starter · #1 ·
hi all.
spent yesterday putting in the arp 2000 rod bolts in the eagle 6.250 h beams for my 408. question is, the spec is .0064-.0068 stretch. or 75 ft#. whitch i did with a stretch gauge. i also measured before and after with a mic. to verify gauge readings. with all bolts at spec they will click my torque wrench at 75#. of course except for one bolt. which will handle 73 ft #. if i torque it to 75 it will stretch to .0071.
am i being too anal about this. or is this a indication of a weak bolt. this is the first time i have used the strech method for rod bolts. so i hope you guys with more experience at this can tell me if this is normal or not.
 

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Are these cap screws(bolt threads into the rod), or bolt and nut style bolt goes through the rod ) ??
From what ive been told and what Ive experianced, You must have the rods resized when you have the bolts (bolt and nut style) replaced. Otherwise the cap will shift and not mate correctly with the rod.
However on the bolt stretch issue, ARP and all top engine builders go with bolt stretch. Not torque. Basicly use a wrench on the bolt and watch the bolt stretch indicator. Then your done.

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71 Pinto
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<font size=-1>[ This Message was edited by: 71hotrodpinto on 2/20/06 2:44am ]</font>
 

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Discussion Starter · #3 ·
these are cap screws and the rods have alignment sleves in them. eagle gave me their blessing to to upgrade to the 2000 bolts from the 8740 bolts. i am just concerned that all the bolts exept for one stretch right to spec with 75#
 

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Ok cool. just remember that tourqe is really more or less affected by friction. the less friction the more the bolt will stretch with a given torque. Thats why ARP recommends a different torque from 30 wt oil vrs their moly lube.
Use the bolt stretch if you have the indicator and dump the torque wrench for the con rod bolts.
good luck
 

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Discussion Starter · #5 ·
i was hoping if someone that has done this a bunch of times could say if i got a bad bolt or if they see this on every build they do. it is just weird that one bolt out of 16 feels funny.
 

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Use one method or the other not both. Bolt stretch is much more accurate than torque readings due to the varied amount of friction between the threads.
 

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Discussion Starter · #8 ·
i was using a torque wrench only for verification of the bolt integrity. anyway i went out and swapped the bolt in question to a different spot. and it felt good when it was streched to spec. i thank you guys for your input.

later, tony
 

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You measure the bolt before and after - if it returns to the before spec it should be OK. If not, it's stretched and it should be tossed.
 
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