Re-Torque Cometics?
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TECH Apprentice
Joined: Sep 2005
Posts: 334
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Re-Torque Cometics? Just finished up my heads & cam install tonight. I've got .040" Cometics, sprayed with copper, and torqued to 90# with ARPs lubed with 30w. Should I re-torque them? If so, when?
90#'s? Jeez, you trying to pull the threads out of the hole? It's only supposed to be like 72#'s I think???? Either way, I would crank the car and let it heat cycle a few times. If the gaskets don't leak, don't mess with them. If they do drip, run over all the bolts after the engine is cooled. If they continue to leak, go get a few radiator tablets from GM, but only the GM ones.
you using studs or bolts? diffently let it sit 24hrs, then retorque. if it is a n/a motor, torque it and leave it be, if it is a fi motor, make a full boost run, let it cool all the down, and retorque.
Has anyone really been able to torque them more after letting it sit from a heat cycle? I tried on both my head changes and they didn't budge ever. More of just a pre-caution?
Dan
Dan
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Originally Posted by MiaSSmaro98
Ive Heard U Can Tq Them More With Oil Then Arp's Own Lube
As for the 90# comment I made earlier, I just saw that he used oil. Not so bad in that senario.
Yeah, ARP's lube is just a better lubricant than oil is...the better the lubrication the more consistent and accurate the clamping force due to appropriate toque provided by the fastener is...it's the same reason you measure rod bolt stretch, and it's the same reason why lots of fasteners are a degree torque spec rather than a ft*lbs spec...that way if Joe uses motor oil and Steve uses Mystery Oil, and Bill uses assembly lube...they'll all holefully get close to the same clamping force...overtorquing is stupid, it's just bringing the fasteners closer to the point of elastic deformation...which will result in a problem, be it a leaky head gasket, a bolt that damages (or completely ruins) the threads in the block on the way out, a warped head, deformed cylinders around the fastener due to the block being bored and honed with torque plates at the correct value, not 10-15 ft*lbs over the correct value.
The know it all's know it all
Joined: Oct 2006
Posts: 500
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Here is the correct procedure.
tq head studs in steps 20-40-60-80 lb ft
Back head studs or bolts off
re TQ in steps again 20-40-60-80
Let sit recheck all head bolts.
also this only applys obviously to ARP head bolts or studs do not use this method with TTY bolts.
GM has a TQ loosen Re TQ then turn method.
the TQ steps help to seat the gasket. If you follow this procedure you should have zero sealing trouble and no bolt stretch. cycling the bolts 2-3 more times may not be a bad idea as it will get them nice an eleastic.
Peace out.
tq head studs in steps 20-40-60-80 lb ft
Back head studs or bolts off
re TQ in steps again 20-40-60-80
Let sit recheck all head bolts.
also this only applys obviously to ARP head bolts or studs do not use this method with TTY bolts.
GM has a TQ loosen Re TQ then turn method.
the TQ steps help to seat the gasket. If you follow this procedure you should have zero sealing trouble and no bolt stretch. cycling the bolts 2-3 more times may not be a bad idea as it will get them nice an eleastic.
Peace out.
I wouldnt bother. I didnt retorque mine and left them for about a year, I finally checked them last week when the valve covers were off and they didnt loosen at all. Cometic .040's with arp stud kit.
90lbs is good using oil, **** i did 85 lbs with ARP moly lube, those bitches are clamped down good.
Yes, the new torque value with ARP lube is 80 lb-ft. ARP changed the torque requirement in January. Also, if you re-torque after a heat cycle, if you don't back off 1/8 turn then re-tighten you are wasting your time. You won't overcome static friction just putting a wrench on them.
