I have some GM 1.6 Roller Rockers and I was curious are they supposed to be tightened to zero lash? I've heard mixed answers from different mechanics, would like another opinion from the people of the forums

 

All rocker on a hydrualic setup should be tightened to zero lash plus the preload. I would tighten the nut no more than 1/4 turn past zero lash with the cam you have. For a stock or stockish cam 1/2 - 3/4 of turn is good.