Cycling ARP head studs
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From: Cecil County, MD
Cycling ARP head studs Anyone ever tighten and loosen your ARP head studs a few times before doing the final torque? I was talking to a Grand National guy and he said they were having problems with pushing water etc. they started using this procedure and the problems went away.
Here is a little blurb I found on ARP's site--
1. The friction factor changes from one application to the next. That is, the friction is at its highest value when the fastener is first tightened. Each additional time the fastener is torqued and loosened, this value gets smaller. Eventually the friction levels out and becomes constant for all following repetitions. Therefore, new fasteners should be tightened and loosened through several cycles before applying final torque. The number of times depends on the lubricant. For all situations where ARP lubricants are used, five cycles are required before final torquing.
Frank
Here is a little blurb I found on ARP's site--
1. The friction factor changes from one application to the next. That is, the friction is at its highest value when the fastener is first tightened. Each additional time the fastener is torqued and loosened, this value gets smaller. Eventually the friction levels out and becomes constant for all following repetitions. Therefore, new fasteners should be tightened and loosened through several cycles before applying final torque. The number of times depends on the lubricant. For all situations where ARP lubricants are used, five cycles are required before final torquing.
Frank
I have done it both on bolts and studs. If you could get the undercut studs, those would be better also. But your kinda applying more load/torque on a bolt then a stud imo. Pushing down and twisting with a bolt, unlike just pushing down on the head with a stud.
You are wearing the threads together as a pair. I have done it but less cycles. The other thing you would be surprised at and most don't do is a re-torque after two heat cycles. Back each nut off 1/8 turn then tighten to the torque value. It will usually go beyond the 1/8th turn it was backed off. On my last head swap I re-assembled with the old exhaust gasket and a few other "used" pieces to do the heat cycles. Once I removed the exhaust and such so I could re-torque the studs I then assembled with the final gasket sets.
you guys know that ARP came out with "ultra-torque" lube? it will allow you to get a more accurate torque reading. and yes, you should cycle the bolts before the final torque sequence
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I did use the moly lube, that is some slick stuff!
Just to clarify, by cycling I don't mean coming up to the final torque in 3 steps. I mean once you get to your final torque back off and retorque each bolt 5 times.
Here's what I did. Torqued the nuts in 3 even steps reaching 80ftlbs. Then when through and backed off one nut at a time and retorqued it going through the torque sequence. I did this on both heads 3 times. I will do a final pass tomorrow.
Just to clarify, by cycling I don't mean coming up to the final torque in 3 steps. I mean once you get to your final torque back off and retorque each bolt 5 times.
Here's what I did. Torqued the nuts in 3 even steps reaching 80ftlbs. Then when through and backed off one nut at a time and retorqued it going through the torque sequence. I did this on both heads 3 times. I will do a final pass tomorrow.
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As for the Moly Lube, I wasn't aware they had out a new version. I did know they had been going back and retesting many of their fasteners and then revising the torque values. For example, after laboratory testing, they increased the LS1 head studs from 70 lb-ft to 80 lb-ft.
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We do the stretch and relax method on the engine stand as stated above to avoid having to re-torque while in the car. We will let the studs sit stretched for a few days, then relax and re-torque and so on....
