Pelican Parts Forums

Pelican Parts Forums (
-   Porsche 911 Technical Forum (
-   -   Race Ware Nuts Backing Off??? (

JTO 02-02-2004 09:07 AM

Race Ware and ARP Nuts Backing Off???
Hi All,

I need someone like Wayne or John W to confirm what was told to me about my engine Friday. Keep in mind this engine was fully rebuilt with Timecerts, ARP hardware, etc. I had Stuttgart in Portland examine my cylinder head studs for torque due to some light oil leaking at the case/cylinder junction. They indeed found a few of the driver's side nuts at around 16 f-lbs, indicating loss of torque. They said that there was no indication of head studs pulling upon their examination. They said that there have been several occurences of Race Ware and ARP nuts coming lose. The nuts were retorqued to spec. They suggested that if upon rechecking the torques in a couple of thousand mile they are lose again, change to the Porsche nuts and washers.

Has anyone heard of this happening; the nuts backing off? Stuttgart has a good reputation among the Portland Pelicans and the PCA. I need someone to call BS for me. John? Wayne?

Thanks you,


JTO 02-02-2004 09:47 AM

has anyone seen or heard of these nuts backing off?


Rot 911 02-02-2004 09:56 AM

Sure is news to me. Did you retorque the heads after the rebuild? Did you time cert the case (forgive my ignorance, can't remember if '75 still had the mag case)

JTO 02-02-2004 10:06 AM

Hi Kurt,

The case is a 7R mag case.

It is debateable whether retorquing a timecerted Mg case is good or bad. I didn't retorque the nuts. Stuttgart checked them for the first time Friday (after about 4500 miles on the rebuild) and found a few at 16 or so ft-lbs.


Rot 911 02-02-2004 10:12 AM

Time Certs are very strong and I believe can be retorqued, but with a mag case, I would be more likely to believe that the studs are pulling as opposed to the cylinder nuts backing off. I sure wouldn't go but another 500 miles before I rechecked the torque.

JTO 02-02-2004 10:16 AM

My engine rebuild work order called for Timcerts and ARP studs and hardware. The hardware was confirmed by Stuttgarts. They inspected the studs the best they could and stated that they could not see any sign of the studs pulling. Of course, for me, the sign was the torques being low! But, I know very little about this topic and need someone with a lot of experience to seperate the BS from fact.


JTO 02-02-2004 10:36 AM

For those who care, it appears that the nuts backing off Raceware and ARP head studs does occur. The thermal expansion rate of the studs does not match the engine well. As the engine thermal cycles, the nuts loosen. The solution provided to me by someone that I trust very much in the Porsche world (Steve Weiner) is to retorque the studs very carefully during each valve adjustment. Ultimate fix, 993 TT studs. These you can torque and they stay that way. I had a good education today.


Wayne 962 02-02-2004 11:07 AM

Another view on the topic. First of all, I haven't heard of any problems with the ARP, RaceWare, or original steel studs losing torque. Second of all, it's nearly impossible to tell whether the original studs have lost torque because the conditions for tightening them are not exactly the same as when you rebuilt the engine.

That said, I do recommend a retorque of the studs when you adjust the valves on mag case engines. The aluminum cases don't ever seem to need it, and if they are corroded and made out of Dilavar, then you could end up breaking them...


ChrisBennet 02-02-2004 11:42 AM

Just a note; you subject line says Raceware but the body of your message says you used ARP.

JTO 02-02-2004 11:42 AM

Hi Wayne,

Thanks for your response. The good news is that the answer to the question of whether or not my head studs are pulling was answered. Stuttgart was able to retorque them to spec. The case was timecerted. That's of course what I was hoping to hear. Retorquing the studs each valve adjustment is no big deal.


JTO 02-02-2004 11:43 AM

Hi Chris,

Thanks, I fixed it. Sorry for the confusion.


Superman 02-02-2004 11:47 AM

Bringing a fastener up to proper torque cannot be bad, magnesium or no magnesium. I retorqued mine two or three times, and they seem to be stable now. Those retorques were very minor. Maybe one lb/ft.

Also, I have been told that when studs pull from mag cases, then cylinder tops and cylinder head mating surfaces get beat up. When this happens, those surfaces are no longer flat. If you then try to timecert the case and reinstall the cylinders and heads, the curved shape of the mating surface will prevent a good seal, the parts (cylinder and cylinder head) will rock against each other and eventually loosen the head studs again. I am told that these nuts will continue to loosen until the mating surfaces are trued (flycut).

JTO 02-02-2004 11:55 AM

Hi Superman,

I hope that is not happening in my case! Time will tell. I am going to relish the good news I have received for now.


All times are GMT -8. The time now is 11:16 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.