They all have an internal passage to feed the rocker arms. Plug the hole with a pipe plug. It sounds like somebody before didn't know where to route the filter lines. The lines should run from the same passage the oil pressure line exits the block to the top side of the oil filter. And from the bottom middle of the filter to a passage near the middle bottom of the block. HTH.


-Tim
'51 Chevy 3104 w/'56 235, 848 Head, HEI Dizzy, Corvette Cam, Split Manifold and Dual Carter YF's