Listen guys. The clearance issue is a symptom as stated, not the problem. The problem is incorrect stand position for a roller rocker. It doesn't matter which roller rocker you use, or whether it has clearance or not, the fact remains that the stand is not correct and that causes poor geometry.
I haven't clearanced a rocker in over 15 years, because I haven't had to. Once the shaft is relocated, there is always ample room between the rocker and the spring/retainer. Pick your favorite rocker arm, Harland Sharp, Crane, Comp, PRW, Speedmaster, Erson, etc., and they will still need the shafts relocated as long as the top has a roller on it.
For all of the praise heaped on the Harland Sharp rockers, they are actually one of the worst for rocker geometry, no matter how nice they look when bolted to the head. I know, I know, I should be burned at the stake for knocking Harland Sharp rockers, but anyone who knows me, knows I call it like it is with every brand. If it's wrong, it's wrong.
And once again, the pattern being centered is a function of rocker arm length and has nothing to do with proper operational geometry. Change the valve stem tip height, the rocker length needs to change. Put a 1" longer valve in the head, and the rocker will be a lot longer to reach the valve tip. It will also roll right off the top of the valve. But, move the shaft, and it will operate correctly, just like any other valve length or rocker length would.
