If you can just feel the rocker move when the adjuster isn't loaded up on the valve, it is good. It might take a few shots to get the feel of it due to the tension of locking them up with a 12mm ring spanner affecting them, but you'll get it eventually. But it has to be done hot. The old adage was "a slappy tappet is a happy tappet" but my lecturer would respond to that by saying - "until the tappet beats the head off the valve and half your lift is gone..." You'll get it running nice and quiet and have as much lift as the cam is capable of, which is a good thing. And the repetitive shock of a loose tappet will weaken a valve (image hitting a nail 3,000 times a minute with a hammer - it would turn the nail into jelly)