ARP Studs and torqueing....

[zigg]

There's a guy on "another" site that has been reading the ARP website. On it, they mention proper ways to torque bolts. It mentions doing the fasteners up to torque and undoing them 5 times before final torquing.

One of the guys is under the impression that he needs to torque his headgasket studs up to the 85 ft. lbs, then release them 5 times before final torqueing.

Does this make any sense at all. I thought that headgaskets were a one time thing. Once they are clamped you can't unclamp them and do them up again over and over and still get a good result.

Any thoughts?

Zigg

 

[typ4]

as far as I know that procedure is only for the con rod bolts, I could be mistaken. Will have to double check

 

[Diesel Fly]

Basically, torque on fasteners is a measure of fastener stretch. In the case of bolts and studs (depending on material) it could take a few "stretches" before the final reading will be accurate.

 

[icanfixall]

I can't feel right about torqueing and untorqueing 5 times before "things" are correct. I have worked on steam turbines for about 30 years and we NEVER did that. Sure, most of our studs were large. Some were about 6 inch diameter and around 5 foot long but they were still only torqued 1 time. Even the jet engines we had were never torqued 5 times. If someone feels they must do this with the ARP studs then I would do it on some kind of "test" stand. Maybe do it without any head gaskets in place. That way you wont be destroying a good set of gaskets. Maybe buy a better set of studs!!!

 

[datkinsonsr]

My training was to always bring the torque up in stages on critical items with smooth, steady pulls, following the proper sequence.

 

[tuke]

My training was to always bring the torque up in stages on critical items with smooth, steady pulls, following the proper sequence.

I have to agree with datkinsonsr I have never heard of loosening then retorqueing.

 

[obinella]

zigg
i read that other site post and wondered if he wasn't misreading the instructions. could it be they want the torque brought up in five stages?

never heard of pre stretching 5 times before using and yes the gasket would be toast

 

[69oiler]

hmm. i just torqued my studs to the specs, in 2 or 3 stages, one time. still holding together.

 

[typ4]

i checked out the arp site and they do reference five cycles of torqueing the rod bolts before final assembly if you dont have a strech guage. I have access to one and it is amazing how close the specs are.

 

[TLBREWER]

I can see the stretch concern for rod bolts on a 10,000 RPM race engine, but not on these engines. And certainly not on heads. Those headgaskets are expensive and I wouldn't want to take the chance of eliminating their effectiveness by re-torqeing several times.

Tom

 

[zigg]

zigg
i read that other site post and wondered if he wasn't misreading the instructions. could it be they want the torque brought up in five stages?

never heard of pre stretching 5 times before using and yes the gasket would be toast

I can see the stretch concern for rod bolts on a 10,000 RPM race engine, but not on these engines. And certainly not on heads. Those headgaskets are expensive and I wouldn't want to take the chance of eliminating their effectiveness by re-torqeing several times.

Yup, My sentiments exactly.

Zigg

 

[reklund]

The correct way to torque ARP Head Studs is in several passes, using their fancy ARP moly-lube stuff. That's how I did the ones in my Supra, and it's still holding together with a steel headgasket and 25psi of boost blowing through it....

I started with 20 ft/lbs and worked my way up to 85 ft/lbs in 10ft/lb increments. I let it sit for 5 days while I went through the intake manifold, built the fuel injection harness, and cleaned stuff up. I checked them again before I put the camshafts in the engine, and they each moved a tiny bit before my digital torque wrenh beeped at me. I doubt the stretch that occured over those 5 days was enough to matter at all though- you could put 'em in and run 'em the same hour, and it wouldn't matter any...

Ryan

 

[Rawpower]

I did it like reklund did... 4 stages and retorque later. I should probably check them since the engine was just rebuilt and doesnt have many miles.