Re-torque of head studs

[buickboy]

I did a search and read a lot of threads and no where could I find an actual description of the actual re-torque technicque. By technicque I mean after intial torque do you loosen the stud nuts and then retorque to spec or do you just pull on the wrench till the torque is reached and it clicks.

Mitch

 

[Audie1]

Read over this....should help you out.


http://www.turbobuick.com/forums/general-turbo-buick-tech/309697-headgasket-installation-studs-help-needed.html

 

[buickboy]

That is the thread I found in my intial search and no where does it describe the actual re-torque technique. On a retorque do you back off the nuts and bring it back up to max torque spec, or just check the torque spec?

Mitch

 

[Audie1]

That is the thread I found in my intial search and no where does it describe the actual re-torque technique. On a retorque do you back off the nuts and bring it back up to max torque spec, or just check the torque spec?

Mitch

Back off a quarter of a turn and retorque to 85ftlbs (if that's what you are using). Retorque in sequence. :smile:

 

[Nick Micale]

......I mean after intial torque do you loosen the stud nuts and then retorque to spec or do you just pull on the wrench till the torque is reached and it clicks.

Mitch

You have to decide which to use.

Even the "experts" differ on which method to use. Like many ways of doing things, there is not a clear line on right or wrong, but what works for you in your situation, or what you are comfortable doing.

Also, many other factors enter into the decision - type of gasket, iron head or alum, block and of course how is the engine to be used among others.

My personal opinion is just doing it, either way, is a good thing. :biggrin:

 

[Race Jace]

retorque to the proper amount and note the position of the wrench. loosen the bolt 1/2 turn and rertorque again (without removing the socket from the nut) and note where the wrench goes to this time. Sometimes it is the same sometimes it is a little more. a little more is always better in this case.

hope this helps

 

[yullose]

Think of it like sex.

The act of doing it is more important than how it gets done.

I think that's what Nick meant to say.

 

[buickboy]

Thanks Jason. Actual procedure always beats philsophy in the real world.

Mitch

 

[Race Jace]

Thanks Jason. Actual procedure always beats philsophy in the real world.

Mitch

, i like this.. lol. also on the retorque we have been torquing them to 90 ft/lbs with good results. (this is with ARP studs)

 

[bison]

I re-torque as Jason described but i always try to move them without backing them off first. If they go i go till it clicks. If not i back off and proceed to re-torque. I do this at least 2x after running the engine after its cooled overnight. I keep retorqueing till i get nothing extra.

 

[S10xGN]

Back from last year!

My headgaskets (dual GM shims/head) are lifting enough to push coolant over 15# boost so I'm about to retorque my ARP studs. I spent all afternoon removing the headers so I can get to the bottom row. F'ing S-10 engine bay is small! Do I need to relube everything with the ARP paste? My plan was to mark the socket for orientation, then back off 1/2 turn and retorque to my original spec (75#) and once there possibly to 85# this go-round. I like Bison's idea of checking first to see what the original torque was at and will incorporate this in my steps.

Anything else?

 

[turbofabricator]

Back from last year!

My headgaskets (dual GM shims/head) are lifting enough to push coolant over 15# boost so I'm about to retorque my ARP studs. I spent all afternoon removing the headers so I can get to the bottom row. F'ing S-10 engine bay is small! Do I need to relube everything with the ARP paste? My plan was to mark the socket for orientation, then back off 1/2 turn and retorque to my original spec (75#) and once there possibly to 85# this go-round. I like Bison's idea of checking first to see what the original torque was at and will incorporate this in my steps.

Anything else?

If they've lifted, time to do over. The sealant is hurt and no retorquing will help. Sorry.
In aviation, if you click your torque wrench more than ONE time, you must replace the fastener. On tubing we MUST follow this principle. If we click the torque wrench more then once, we must replace the whole tube. It is considered over torqued. So, with that said, if you are re-torquing bolts/studs, loosen first, THEN re-torque to spec. Pull (not push) on the torque wrench handle smoothly. Torque in steps and always pull on the torque wrench to ensure a proper torque.

 

[Nick Micale]

If they've lifted, time to do over. The sealant is hurt and no retorquing will help. ............. if you are re-torquing bolts/studs, loosen first, THEN re-torque to spec. Pull (not push) on the torque wrench handle smoothly. ....

Depending on the sealant used, it might be OK if is the copper coat spray was used. We had had good success with resealing the steel shims, but don't know if the silicone sealant would, as we have never used that as a sealant.

After checking around with some industry experts since many other opinions on re-torque procedures differed, Ken is "right on" with them using his procedure. You cannot achieve the proper target number unless sliding motion is used to overcome friction like done originally.

It does seem to me in the years I have worked with ARP bolts and studs on cylinder heads, the threads become "seasoned" with use and hold their original torque better.

When installing fresh heads and torquing in sequence, I will go over them again, w/o loosening, to be sure none were missed.

Occasionally, to be sure a bolt, or nut on a stud, has not loosened I will check by pulling to a value below the original number. The threads on studs hold up well, but the nuts I usually replace after used 3-4 times as that is usually the reason for the torque value to decrease.

 

[S10xGN]

Would a leak-down test show anything? Yes, I'm trying not to have to pull the engine. I'm working solo with a bad back to boot. I looked back in my records and I did use the silicone, not the copper spray...

This thing has no problems until the boost gets way up there (due to my WG hose being rotted off). I have Dakota Digital gauges that seem a little slow on the response time, so the knock gauge goes off and I let off before the boost "shows" high (but in reality actually "is" high). When the hose was intact, I was able to run 24# with Julio's Alky kit...

 

[S10xGN]

Well, I did one anyway. I have no idea what is considered "good", but mine ended up at 88/88/90/84/92/88. Since the manifolds and valve covers were off, I could not tell where the air was escaping from. I'll be prepping to pull the engine sometime this week...

Hey Nick, will I be OK at 90# on my ARP studs or is this tempting fate? I'll likely be using RJC's single shims w/silicone since the MLS gaskets require specific finishing on the head and block surface and I have no idea what mine will look like...