First I would check for proper pushrod length.

To adjust turn over till the lifter is on the base of the cam "where the cam lobe has no ramp" start tightening the poly lock to take up all the slack. Tighten slowly till you can barely spin the pushrod with the tips of your finger. Then go 1/2 turn on the poly lock.
With the wrench holding poly lock tighten down the set screw.