noise question

[E Montague server]

I've got one that I can't solve.

The motor is making a ticking, almost like a cam chain hitting a cover. Increases with RPMs

Not a rod knock. 

I've had the valve caps off, checked and adjusted valves, CCTs work fine.  No odd wear marks on the cam chains and none of the caps or towers. I can't seem to figure it. Even pulled the stator  cover to check the starter clutch

ideas appreciated.

Ernie