I own a repair shop in Las Vegas. Have a customer with a 1967 Dodge D-100 with a slant 6. He supplied all the parts to overhaul the engine. I removed the engine, sent it to the machine shop, had the block bored, and engine built. It received a new crankshaft, rods, pistons, rings, bearings, camshaft, timing chain, oil pump Etc.
Ran engine for first time. Began making a rotating noise imediately. Not rod or valve noise though. While running it for under 3 minutes trying to identify the noise, I heard a loud noise like somethng hitting the oil pan. Shut it down.
Found the oil pump drive gear in pieces in bottom of pan and cam gear trashed. Suspecting the machine shop left debris in the oil galley that caused the pump to lock up mometarilly and cause the failure, I replaced the camshaft & oil pump again, paying close attention to detail. Installed the cam with the upper timing gear only and the oil pump installed, no lifters, and rotated it to check for any alignment issues, binding or noise. Spun freely by hand, felt smooth, no noise. Finished assembly.
Started engine, Same noise. Shut down before it broke the gear again. Please advise!! What has this machine shop done wrong?
Please email me @ swingshiftauto@aol.com

What a PITA...
It is really hard to trouble-shoot noises wiith-out hearing them yourself, and even then, it can be hard to find the cause.

Me, I would confirm that the noise is not coming from something unrelated, like the, flex plate, starter, water pump impeller or other accessory.
I would likey change the oil pump as a test.
After that, it is a listen and look "treasure hunt" or another round of "wait until it breaks" to find the cause.

Keep us posted on what you find... I'm always learning new stuff!
DD

I second that...had a high pitched screech before my hipo engine break in ended...I think the pump rotor must not have had the correct clearance when assembled at Mellling...

-D.Idiot