engine noise - braintrust help
 

Hope you can help me with an engine noise. Newly rebuilt engine that makes a clatter sound kind of like valve tappets crossed with an exhaust leak. The sound is loud at idle or when I lift off the gas and goes away entirely when I open the throttle. At 60 mph it is gone with the throttle open constantly. Any thoughts about what could this be?
911SC 1980.

the best to help you would be either make a sound recording or video

Ivan

Do you have hydraulic chain tensioners?
Is it the chain on a trashcan sound?

Yes, I added hydraulic lifters some time ago. The sound could be described that way. Do you have any idea about how the sound depends on throttle position? I am thinking maybe something is dependent on vacuum.

VIDEO VIDEO VIDEO Or this thread wont work.