Max, The noise you've described doesn't sound like any valve related noise I've ever experienced.I think you're going to find a more major problem giving a noise in relation to the valve movement described...
Good luck
I agree, it doesnt sound like any valve issue I've hear heard, and I've been worried about a deep bearing problem ever since... that's why the pan is off...
The only correlation to the #1 intake valve is that the noise doesnt happen on every rotation of the crank based on the piston position, it's every 2 rotations of the crank synchronized with the intake stroke. So, I assumed cam in connection with the intake valve, or something in the valve mechanics itself... But I'm gonna reread your post over and over until I understand it, and see if I can perform some of those dianostics....
