429 Ford Thunderjet, knocked for a total of about 20 seconds before I shut it off. Ran perfectly fine, had good oil pressure, temp was good. I will have the crank turned .010 and the rods hogged out .010 with ARP bolts. It started knocking for about 10 seconds, then I shut it off. Bewildered, started it back up, started knocking again. Shut it back off, haven't touched it since. Opinions?