newly rebuilt and a knock

[JKY]

Originally Posted by McMimmcs

What is practical is contacting rebuilder, apprise him of problem and seek his advice!!

In the original post he said, "The rebuilder says it was fine when it left his place and i must of done something like maybe the timing was off."

Looks like he's already done that and the builder is telling him that the engine was fine when it left, making it the owner's problem.