I'm with Cab, that it helps keep oil away from the seal which mighta been a nightmare of comebacks for Ma back in the day with oil leaks being the cats' a$$ with people complaining about oil stains on their driveway while it was still under warranty. On the other, early or late I forget which used the drip plate & the other used a bolt in the upper pass (iirc) hole with a 1/8" hole in it for drip lube for the chain. I drilled/tapped the front of the pass horizontle oil gallery for an alum pipe plug & drilled a 1/64" (.015") hole in it & a 3/8 hole in the cam plate for a constant mini squirt past the plate out onto the chain. I ain't sure if it is needed or not, that splash might be enough as is but my OCD convinced me that it needed it. Also I drilled the same hole in the pipe plug by the intergear to lube that gear meshing. When you preoil you will be able to see the squirt & contrary to what some say .015" is enough. I ain't sayin you cant drill an iron npt plug with that small of a drill bit (go real slow with lube) but alum is far easier/quicker. EDIT I would use the drip plate if you have it and drill the bolt 1/8" (easy to do & every bit helps).