Started my 340, IT KNOCKS! fresh rebuild HELP!!

OK , Again I pulled the engine tore it down "had the internals balanced" put it back together ..Fired up like a dream .. BUT I'm hearing a KNOCK in the engine. I haven't spent much time on timing it. Just heard this knock and after about a minute shut it down... ANY thoughts??? Did I do something wrong or miss something or is it just sounding that way because.....?????? Need help...????????
Author: admin