[454_72_4X4]

Another thing of importance. The rocker studs need to have a machined flat surface on the top. If they don't have the flat surface for the allen set screws to tighten down on they will not stay adjusted.
Stock rocker studs are not machined flat and some aftermarket aren't either. I ran into this on my TFS heads so I bought a set of ARP studs, which are machined flat, but they wouldn't fit because the hex part was to big the clear the guide plates. (This shouldn't be a problem on other heads).
I had to have the TFS studs machined.
All this while I was 800 miles from home....