Surprise find

[RUNNERBUN]

I just picked up an early 1928 engine (engine number 15,???) and couldn't wait to tear it apart to see what I got. The engine has the early Beaver tail crank, the connecting rods are the ones that have the cross section shaft. Rear main has the smaller drain tube. The whole thing is in very good condition and I will be just cleaning it up and put it back together as a spare engine.
One thing that surprised me is the rear main bearing cap. As you can see from the pictures a felt seal has been added to the rear groove where the crank slinger goes. I have never seen this done and was wondering if anyone has had experience with this small modification.
Did it or does it work to reduce rear bearing leaks?. Is it worth doing?
Your thoughts and comments are welcome.

Runner