Saw this post about the Eastern tappets. I am the Chicago associate Tom Cotton spoke of. Hopefully, this vacuum issue has been solved. If not please contact me. The holes are problematic since they cause a vacuum leak. The oil return from the tins on Knuckleheads is achieved through vacuum. Unless you TIG weld or silver soldier the holes shut you will not return oil from the tins. The other issue with the Eastern tappets is the soldiered connection of the top and bottom sections. I have personally had them separate. After sharing this story with a vintage mechanic last fall he had a freshly built knucklehead come in spilling oil out of the tins. After lifting a pushrod tube he identified the tappets with holes. Brazed them shut and the problem went away. Need oversize .005+ get the S&S tappets. Also make sure the two intake lower tins have the 1/16 holes in them. S&S is also offering a breather that has longer duration for pulling oil from the tins.