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?

 

I would do it after 24hours. then again after heat cycling it. dont torque it while the eng. is still hot though.

 

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.

 

i would of used arp's moly lube-i agree 90ibfts is to much

 

They recommend 80 with oil and it is common practice to over-tq them by 10-15ft-lbs.

 

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

 

Ive Heard U Can Tq Them More With Oil Then Arp's Own Lube

 

You have to TQ them more because you have to over come more friction w/ oil. Your not actually gaining clamping force. In actuality, 80 ft lb's with oil is the same as 62ft lb's with ARP 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.

 

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.

 

It's best to use the arp lube

 

^^^EDIT- I just realized this thread is old and worthless.

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.