I have a Lq9 with 79,xxx miles making noise. It has cro moly pushrods as well as the comp cam trunion upgrade. The noise sounds identical to the sound that you can make hitting your knuckle on the underside of a wood table softly. Just imagine that coming from the engine bay so a bit quieter. It only happens while in drive under load. In park it will not make the noise no matter what you ask the engine to do. I cannot check it in park since engine will overpower brakes before the troublesome rpm range comes up. (2500). Oil pressure is 40 at idle with 60 going down the road. I'm at a loss. Any help would be appreciated and I will answer any questions that may help solve the answer.

truck is tuned by Justin at blackbear and runs 91, even with octane booster, noise remains. Ambient temp is 68. Cam is stock, just upgraded valve train.
5W 30 synthetic

 

Sounds like timing knock. If you have tuning software you can log knock to see what is happening. May need to back off the timing some.

 

Old thread but ended up being an exhaust leak from the back of the drivers side manifold

 

Thank you! I wish others who get solutions to problems would report back like you did,

 

I worked on a BBC 454 once had a similar noise, was the main bearings.

 

Agreed. It drives me nuts to do a search on here, only to find a thread started, with no ending.
Thanks for wrapping this up nbs.