Oil pump priming. Vaseline needed?
Back, early 90s, I had a 390 rebuilt/complete assembly, installed, fired up and went for a drive. Totally clueless about all this prelube stuff, hearing a lot of rattling , I immediately brought it home. A guy enlightened me about the cause and suggested Vaseline.
I took the miserable route of dropping pan and fighting the pump out. Reinstall.
It picked up immediately, I was one happy camper!
I learned the real hard way.