308 Timing chain slack question

Can someone please tell me what amount of slack is acceptable in a 308 timing chain? And what is the purpose of the "slider" attached to the inside of the cover? Mine clicks when I hand turn the motor, which is out and on a stand, Is this normal?

Comments
When I hand turn the motor there is an audible click with every rotation, there is a fair amount of slack which changes between the upper and lower sections of exposed chain. So when one side is tight the other side is slack.
When I remove the timing cover and hand rotate the motor there is no click.
Notice the wire wrapped around the cam gear bolts. Was this factory Hudson?
The timing chain snubber or silencer was changed and in the last iteration it was: