Scary engine noise please help
 

Hey guys. I'm building a 65 ford f250 with the 1990 12v 5speed 4x4. I bought a used engine for the project. Put a new injection pump on it and I have around 4 or 5 hours of run time on engine. Not until recently I built the exhaust and and now I can hear some sort of engine noise, like a tapping. I started cracking injectors and once I got to #6 it went away. So I put some new injectors in it and it still makes the noise. The noise is real loud at cold start up. Once the engine start warming up I don't think I can hear it anymore. You can't hear it from right on top of engine. You have to be standing by side of truck or in cab. Also I'm getting a tiny metallic sound from my bellhousing. Do you think a cracked flywheel or bad pressure plate could be causing engine noise? I have plenty of oil pressure 60-40psi, I already adjusted my valves, motor runs great, no misses at all, I'm just hoping I'm not losing a bearing or wrist pin. I'm going to pull my oil filter tomorrow and see if I have anything is in there. Any input or ideas would be great thank everyone!