Ok...
This is something that's always been pretty straight forward for me, at least until now. I've installed a couple different sets of aftermarket gear, which consisted of solid shafts, spacers and whatever rockers I was using at the time, plus the usual ancillary hardware. The whole thing was always pushrods, rocker assemblies with the rockers spaced to center the adjusters on the valve stems and everything torqued and set to specs.
My most recent efforts have involved installing high ratio rockers (1.25:1) on my past 1641 and present 1835. On the 1641, I always set the lash to .006", which worked pretty great. The 1835 long block came with a cam card for the Engle W-100 cam the builder had used, which put the lash at .004". I set it up this way, only to find a light miss and occasional backfire on the 1-2 bank. I readjusted the valves back to the old .006", which cleared up the miss, but left the engine a tad short on muscle, or at least that's what I attributed it to.
Now, I'm reading a vague and ambiguous article that talks about shimming up the rocker pedestals to achieve proper "geometry". The article, which refers to the installation of a set of 1.25:1 HR rockers, states, "We determined that the rocker pedestals needed to be shimmed up .060 to get the proper 'geometry'. We torqued the studs at 18 foot pounds and set the valve lash at .006."
My questions are these:
First, how did "we" determine that the pedestals needed to be shimmed up .060"? If there's some magical equation for this, I can't seem to find it, and the statement in the article suggests that .060" is a fluid variable which could change depending on your set up.
Second, why is it necessary? What are "we" accomplishing by shimming up the pedestals?
If anyone could shed some light on this, I would once again find myself owing a debt of gratitude to the group.
PEACE, and ride safe!