Hughes rocker arm pedestal shims

If the pushrods are too long due to milling you need to buy shorter pushrods.
On a Mopar (or any shaft system) if you put shims under the shaft, you affect the geometry of the rocker and the valve stem tip in a negative way. That's because the centerline of the valve stem is tilted towards the shaft. If you drew a line up from the valve and up through the center of the shaft (like straight up through a hold down bolt), those lines would eventually intersect. So as you raise the shaft you also push it sideways a little. The rocker tip moves towards the exhaust side of the valve's tip. That's a bad thing for power, longevity, and guide life and it doesn't take more than .010-.020" of shim to cause problems.