Well, Friday was mine and my wifes anniversary so I thought it would be a good time to try to fire up the "new" rebuilt 216. She came to life on cue----what sweet music. We ran it for about 30 minutes, shut her down, readjusted the valves, and tried her again. Lot of bad sounding noise deep in her bowels----like rods knocking. Did not hear this at all when originally running. Pulled the distributor and spun up the oil pump again which was moving oil up to the rocker arms. Ran it again, sounded fine. Came back a coulple hours later same noise when I cranked it. Seems like the pump won't hold a prime. Has anybody else experienced this. Any thoughts would be appreciated. Thanks