04-21-2011, 09:24 PM #1
Carrillo Rod Bolt/ARP Stud Bolt Torque
When installing these how many of you guys cycle the bolts prior to final stretch? The supplied spec sheet states DNE 30 ft. lbs. but if you follow what the spec sheet suggest you will not acheive propper stretch (.0055). I contacted Carillo for clarification and the tech stated "you may have to exceed the torque spec to acheive propper stretch". After a little research on the CARR SM8 bolts I found that most people are torqueing to around 45 ft. lbs. to get the correct stretch. Another factor to consider is the type of stretch gauge used (cheap vs a quality gauge such as the ARP version). If the gauge has a weak spring you will get inconsistant (false) readings. Carrillo also recomended using the Loc-tite heavy duty antiseize (51609) over the ARP lube. During my research I found that the "old" data sheet spec stated DNE (do not exceed 45 ft. lbs.) To put things in to perspective if you simply install the Carrillo rods with the 8mm CARR SM8 bolts and torque to 30 ft. Lbs. with disregard to the stretch factor you WILL suffer engine failure, bottom line is no stretch equals no clamping force. This brings me back to the original question of "do any of you guys cycle your bolts before final stretch/torque?"
With that in mind lets talk about the ARP head studs and the clamping ability of the studs without the ability to measure stretch. Does anyone cycle these prior to final torque? It would stand to reason that some of the head gasket problems may be related to proper torque methods. If these are installed first time, torqued once, the friction resulting from a lack of cycling the studs/nuts could be causing an inpropper stretch of the studs. This unmeasurable amount of friction could be causing an inpropper torque reading or atleast inconsistant. Although the torque wrench measures 85 ft. lbs. per stud the studs may not be stretching appropriately. Many people have reported torqueing these to 95 ft. lbs to keep the gaskets from blowing. This could also cause problems with the studs due to over torquing if you get several that actually have less resistance than the others, less friction (with appropriate lube) equals more accurate torque readings accompanied by a good quality torque wrench. I'm no expert on the subject just food for thought.......
04-29-2013, 04:39 PM #2
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