OK, Like the others said, there is a good possibility that you have either spun a main bearing or the main bearing clearance is too large. I think the point you are missing is oil viscosity. When the oil is cold, it is thicker, once it warms up it thins out as it is designed to do. Also, just cant get rid of the thought that your cam bearings maybe have seen better days. Definitely the first thing to check is main bearing clearance and condition, after you have done that we may be able to help if that is not the problem. If you want you can contact me personally and I will try to elaborate.
ASE Master Auto/Truck
67 RS Convertible
[This message has been edited by AUTODR (edited 03-24-2001).]