NDDan
Guest
I've seen the hole you talk about and believe they are on all of these engines. I also believe they are open holes and don't need to be there unless the application had that very old pump design. I've never pluged one but I can see where it can steal a bit of oil from rod. Don't know if I'd worry as much about air but maybe oil pressure at final point. I do have a strong hunch if that hole was giving a problem we would see plenty of these machines with bad bearing in that spot in particular and others quite alot better. let us know what you find out.