Could it be carbon knock?

 

I hadn't thought about that yet. I will check on it.

 

Did the tensioner release? Either by itself or by slapping it (the sure way).

 

Yes I double checked it before putting things back together.

 

Just to clarify, you did replace all the guides? You did mention replacing all timing related components(-cam gears). The intake guide was broken on both of my HHR engines. I can't help it but think it sounds just like the wife's SS did. Removing the valve cover would be my first step. You can check visually for any unusual cam or timing chain wear.

Good luck with the troubleshooting. Keep us posted.

 

Completely stock exhaust.

I was hoping the video would pick it up. It sounds as though the valves are noisy until the pressure increases. Is it possible a cam gear could be going bad? since they are automatically adjustable I thought that might be a possibility.

 

All guides were replaced and the motor sounds the same after as it did before the swap. I wondered if these motors were just noisy under low boost/low RPM situations.