I installed a rebuilt head from Cylinder Heads International after suffering an early timing belt failure. For the first 2 hours of run time the entire engine was tapping. I took the valve cover off and confirmed oil was present. The engine would tap as soon as you turned it over and sounded to be coming from both cams. After about 3 hours of run time, the oil seemed to have settled in and the tapping quieted considerably. Now I'm left with a left cam that starts tapping the moment the engine comes up to temp.
Any clue what's going on here?

 

What weight oil do you have?

 

Right now I'm running 5w30 but I've never had tapping from using this weight oil. Do you think 5w40 would make much of a difference?