Ford used them as standard in RS1600i.
However, all brands are much a muchness (ford,kent,piper,newman etc)

Basic premise is you want the lifter at its lowest point on the lobe, then ensure the rocker arm is torqued correctly, the gap between rocker arm and lifter should be 0.008 IN, 0.010 EX (those are Newman lash specs, other brands will vary)

Its easy to do, just takes ages as you have to take everything off to then adjust the lifter each time till you get it perfect.