Please try to get your bearing clearance back to specs...which as I recall was .001". That will help. Asbestos laced rear main seals stopped being made by anyone around 1978 (
more on that in a moment). AIG and other insurers demanded it...they would not provide insurance for asbestos in any form after and the gasket companies got hammered with self-insured losses. I was part of the AIG staff at that point. The problem was the courts would just start handing out awards the instant they heard the word. Policy language excluding asbestos didn't become standardized until sometime around 1984 or 1985, however...at least as I recall. Many moons and many courtrooms ago...but I promised more. Please see below.
If you can find a rope seal made with asbestos, that will help. It did work better. Interestingly, I've been watching this for a while and today you can buy 3/8" asbestos rope again. You can see here:
http://www.wealson.com/dust-free-asbestos-round-rope.html You would have to figure out how to impregnate it with graphite (because that is what it was) but it is available. Also you can get it impregnated with PTFE. (
http://www.wealson.com/asbestos-packing-with-ptfe-impregnation.html) You have to deal with China but that isn't nearly as difficult as you might think.
The GMC engine at least has an oil slinger. The 216/235/261 engines don't and in my opinion they should have had one. You can easily add one in those engines by forgetting to remove the lip of the Speedi-Sleeve. The oil that washes over this area isn't under pressure but the flow can be copious and it will work its way out. Also, I use straight 30 weight...and I know, that is a whole other discussion and there will always be some interesting opinions once discussions begin.
Finally if the sealing surface on the crankshaft is rough, you may as well remove the crank and apply a Speedi-Sleeve and some red loctite. Somebody already mentioned this...Jerry maybe or Mike. My experience has been that moisture and acids in the oil
will corrode the surface and make it look like the image you see attached. That will never seal properly until you repair it.
Finally I have seen situations (3 or 4) where somebody drilled holes in the block and cap and set cut-off nails there. This was to keep the rope seal from moving at all, although I'm not convinced it really worked. You can see a couple of images of what I've found below.
Good luck!
