In response to Gordon Stelter's request posted in MMD 120719,
I offer a few thoughts. First, Gordon, if you think the piano is
that deficient, you should sell it and find a piano that more closely
meets your criteria. I personally don't think the piano (Ampico)
is deficient and consequently, doesn't need the modifications you
contemplate. The idea that the striker pneumatics are too big is
a rather curious concept that I believe has no basis in fact.
Properly restored and regulated, the current mechanism, without
any modification, can be a stellar instrument. In my opinion, the
modifications suggested would yield no discernible results.
If the valves are the "upside-down" type, it is okay to modify them to
include replacing the wooden ring (outside seat) with a metal valve
cap. This will lead to clearance problems if the valve body becomes
too thick. That issue may require thicker gaskets between the deck
boards, but that too will create other issues.
The 5'8" Chickering is a fine sounding instrument. I've worked on at
least three of that size and vintage. Two of them were actually were
much older and had the Stoddard mechanism.
I would discourage any attempt to modify the piano (Ampico). It would
be a purely experimental adventure unless you know for a fact that the
modification would make a big difference.
One last recommendation, make sure the secondary valves are gapped at
about .037", but not less than .035". This will allow quick exhausting
of a 6-inch pneumatic.
Good Luck and keep us posted.