Valve closed. right??
I assume you're referring to a closed valve position when the retainer is near the rocker radius. Yes, when we start playing with aftermarket parts we do run into issues like this. I believe I was told .050 minimum, but we also have to live with the fact that the valve is moving all over the place during operation, but should come back as the valve closes fully... I cured my issue, (Crower Enduro rockers on AFR heads), with longer pushrods that raised the rocker up, and also aligned the roller on the rocker to a better position on top of the valve stem as the valve event went from start to finish... Are you dealing with ALL aftermarket parts??? Or trying to blend some of the stock stuff along with some aftermarket parts??.... I also discovered that not all roller rockers use the same profile in the radius area and some offer considerably more clearance than others... I think it was Bob that posted some pictures showing the different brands and their respective profiles...
Ray