911 Engine Case Stud Studs - Install Torque

[tocobill]

I was thinking about this last night while reinstalling the perimeter case studs and misc case studs for my 993 engine. They were removed to have RS quad rings machined into the case spigots. I didnt see any stud torque value for install in manual. Just using good engineering practices of installing until tight and a 1/4 turn.

Curious what the general consensus is on installation.

[Catorce]

It would never be tight plus a quarter turn....a stud is a fastener that uses thread tension to provide holding power. Screw them in hand tight until they bottom out, use loctite blue if you are concerned with them moving. A quarter turn after bottoming out unneccessarily stresses the case.

[tocobill]

Ok. Thanks for the info. These required more force to remove then hand tight and no loctite was present. I installed them 1/4 past hand tight for preload, but I understand over-tightening will stress the case threads. My concern was having them back out or get removed with the nut when disassembled.

Do you know if these have an installed height?

[Walt Fricke]

Studs don't get preload. You don't really need to worry about them backing out when you remove nuts later on - a minor annoyance. But Catorce gives you what you need - bit of blue Loctite. Over time I think studs accumulate a bit of corrosion or the like, which helps keep them in place when you loosen their external nuts.

As to installed height, you can figure that out easily enough - they need to stick out far enough to go through the part they help join, plus space for a washer, and a nut, and maybe a sliver of a thread showing. For some, like the oil pump studs, easy enough to do a trial fit with one. Same, really, for the perimeter studs if worried. Most I think can't be installed too deep - blind holes. The few which have a through hole just go in so they are flush.

The head studs are the only ones, I think, which have an installed height, and that's mainly because of the barrel nuts - regular nuts or flange nuts aren't so particular. It is 135mm on earlier cars, don't know if that is different for the 993, but should be easy to look up.

[cgarr]

Set them to height as said but never bottom them them out in the blind hole


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