Whats that noise coming from my 318?

So i will pull the valve covers and take another video. But how long can i let it run with them off the engine? Anymore ideas are welcome thanks guys.

As stated above, I would remove the belts first to make sure that it isn't something in that area. Sometimes noise travels and it is best to start by using the KISS program.

KISS= keep it simple stupid... after making myself a lot of needless work and wasting money, I finally learned that it really works.