When replacing the timing chain, should I pre-tension the chain by pressing the tensioner arm and letting the tensioner extend to that point? Wouldn't that be better than letting the chain make a few revolutions with the slack in it when first started? When the tensioner pin is removed from the the new tensioneer, it does extend, but the chain still seems to be slock/loose to me.

 

If you are that worried, you could always spin the engine a few times by a socket on the crank to feel better.