I have a 1983 buick Riviera it only knocks when it warms up 5.0 engine any help please?

Changed the oil pump and rod Berings and don't understand what it could be.I have a 1983 buick Riviera it only knocks when it warms up 5.0 engine any help please?Sounds like low oil pressure. You may have a problem with the oil pump, or there is something that is blocking the oil pressure to the hydraulic lifters on your push rods. So it will make a racket until they expand under operating temperature.