Hi!
I just got these lifters http://www.lmperformance.com/6304/43.html.
The difference are that the spring in the lifter are so soft that when you adjust the roller arms the spring in the lifter just compress so you dont now how much you should adjust the nut on the roller lifter.
Someone have a clue how to do it?

 

If you run the engine for a minute or so, they should firm up with oil. To get to that point you could just eye it by adjusting rockers until the plunger in the lifter is still contacting the retainer pin of the lifter.
It sounds like you may not have soaked the lifters in warm oil over night before the install. That usually makes them firm enough for a good initial adjustment.
Only ajust a lifter that is on the base-circle of the camshaft at the time.
Once it's done don't go back and adjust it again because the lifter plunger has collapsed some due to lack of oil pressure.