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I'm not sure that shimming will make it worse,
take it to the extreme i.e. if you shimmed it an inch, the arc of the tip would be passing the valve on the inside, or is my reasoning wrong??

Joe



that was my thought , but that was ASSuMEing the rocker shaft holdown pedestals were parallel to the valve stems , they angle toward the valves it seems, I don't have a head handy to confirm this.



15 degree valve angle which really messes up the geometry. As you raise the rocker shaft it gets closer to the valves.

I have a CAD drawing that details all of this out. It is kind of interesting to watch what happens with rocker arm scrub when you change the location of the shaft. Checking the scrub distance with a dial indicator is a good way to verify what is going on. Then you have an actual number that you can work with.

Sometimes the rocker shaft has to be moved a fair amount before the scrub distance is brought back in line. Ideally you want the minimum scrub distance as well as a centered pattern. That is tough to do with some of the rocker arms that are on the market.