If there is slack on the tensioner side It has to come from chain stretch. If the chain is loose That means the pull side has to be longer. If it is longer that means there is a change in timing. Take the tensioner off and push one side then the other. You will see the cam sprocket move. Movement is timing change. It's a no brainer if you really think about it. I am only stating what I see after seeing many motors done at our shop.
