3.2 case studs questions

[kepperly]

I,m doing some "DEEP" maintenance on my 87 3.2 carrera and while the heads are off, I discovered the dread divar studs
on the exhaust side ( bottom) of the cases. I dutifully ordered the stock steel one for replacement. after removing the dilvar studs,
I was reinstalling the lower steel ones and started searching for
the torque spec's for tightening the studs into the case. The only reference I can find is the installed height of 133-135 mm depending on which manual you look at. Why the installed height and not a torque spec? I realize that the stud can cause a problem if too long with the barrel nuts not having enough tread,
but is this the only issue. I checked the upper steel studs and they vary from 132-136mm, is this stud stretch? They seemed perfectly at home when the engine was assembled and running and no I didn't have any broken dilvar studs at 89,000 miles.
Any input about the case studs I would appreciate.

Thanks
Keith Epperly
87 slant nose turbo look carrera cabriolet

[MBEngineering]

HI Keith just fit the studs to LENGTH with locktight, as you do not torque them into the case.

regards mike

[casperlabs]

Keith,
It is critically important that the studs be anchored mechanically
in the case. If it does not have a positive (outward) axial force pushing against the thread at all times it is going to start "working", and pound out the thread during thermal cycling.
This situation is compounded by KEENSERTs that are deeper than the stud thread, allowing the stud to go in too deep, and create a length problem on the nut end. We solve this in our stud/nut kits by matching the stud thread to the Keensert. This gives the correct installed height every time, and increases the load bearing area in the soft case material. We recommend 20ft-lbs installed torque for our studs with 242 threadlocker (non-permanent). DO NOT quote us on this for the OEM type.
The only time a stud should be installed w/o a case KEENSERT is when an individual stud is replaced w/o engine disass'y. The possibility of introducing parallax in the redrilled and threaded KEENSERT hole w/o a vertical milling machine averages 1 in 3 in our experience.

Bill Ryan
Casper Labs, Inc.