I fitted the closing rockers first (no difference between I or E) , made sure they are centered on the valvestem.
Then shim the cam to make sure the closing rockers are centered on the lobes.
Then the opening rockers, centering on lobes and valve.
Of course this means a lot of fussing about, and it wasn't Always correct from the start, but nearly Always 99% correct afterwards.
As MikeV stated : be sure to fit everything (included the opening rockers) and then check for binding.
Then dismantle and assemble with springs.
We had a batch closing rockers regrinded and rechromed and they had a very small difference on the lobe-diameter.
This means that the point of contact on the lobe is different and the moment of contact isn't the same anymore.
What meant that the openingrocker began to push, but the closingrocker didn't give way (yet).
Being unaware of a problem, the mecanic didn't check for binding.
Fitting them and running the engine went fine, but after a few hundred miles we could throw away rockers,cams and clean the engine for debris
We suspected there is a small difference between the lobe-circle of the Pantah and the Bevels, and as we regularly let them do a batch, the rocker-man somehow messed up (or we didn't give him the correct info)
ciao
ducadini