I have some '66 289 heads machined out for small block chevy valves (1.94 and 1.60) and will be assembling them soon. Do I need to use oil or assembly lube or anything else on the valve stem where it will be in the valve guide?
Absolutly need lube, either will do. Metal to metal is not good for valves, and it will take time to get oil to them, especially if you upgraded to pc seals.