I have added some pictures of the motor and an oil circuit diagram which I believe is correct and what Truckernix is saying. If the diagram is correct I assume the oils makes its way up through the cam via the main bearing. I assume as the motor heats up and tolerances tighten the oil will make its way up to the valve train?

http://s1142.photobucket.com/user/52_Ton/library/52%20235%20Hydramatic?sort=3&page=1


1952 GMC 9430 one ton pickup, a work in progress

1952 1-ton pictures on Photobucket