Bob Taylor said:

> In (3) above, replacing the cross valve seat with a round valve seat
> upsets the geometry balance of the valve system because it changes
> the area of the opening by 30%.  To compensate, and restore the balance,
> the valve body must also be changed.

On the last cross valve piano in my shop, I was discussing the problem
of replacing the valve plate with the piano's owner, who is a engineer.
After much discussion he said "Why not have new plates made that has
the exact area opening as the cross valve plate.

The plates available from Bob Streicher were 1/2"+, if I remember
correctly.  I wanted a plate with a 7/16" hole.

Well, Bob Streicher did make the new plates, and they did work great.
Yes, I did also replace the valve stem with standard action style stems
and valves.  You can hear this piano on my web page at
http://www.pebworths.com/SCA/SCA.html

Al Pebworth
Chesapeake, Virginia