Well, I do know that when I adjusted the valves before, there were a few of them that had bolts that seemed really loose, and although I adjusted the valves to get rid of the tapping, the bolts never really tightened up. Maybe they came loose again. How would I fix that id that was the problem? Would I have to rebuild the heads? Oh, and some of it could be the harmonic balancer. It also has a slight thumping noise when it runs too, but that never really concerned me much, I just wrote it off as the engine being 48 years old.
