Merlin the Wrench,
I'm not sure what happened. I finished this up last week (have off work Tuesdays and Wednesdays) and I came back today to do the compression test like you advised. Anyway, I started it up this morning and the tapping noise was gone.
Could it be that it needed a few minutes for the valves to adjust? Maybe oil was being temporarily blocked from one of the valves? Whatever it was, I am hoping it is fixed. I ran it to normal operating temperature and everything looks good. Thanks so much for your post and help. These boards are great.