[mikedsilva]

Originally Posted by Trackrash

Not sure if it was covered in this thread previously, but there has been some discussion about not using sealant on the main bearing supports. http://forums.pelicanparts.com/911-engine-rebuilding-forum/1033101-disaster-strikes-what-went-wrong.html

The Porsche repair manual is not clear on this. From the Carrera Manual.

True.. it says "mating surfaces"... and it seems that the bearing journals are indeed mating surfaces.
However, it makes sense that adding anything here, is going to potentially alter your bearing clearance.