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MMD > Archives > February 2006 > 2006.02.24 > 10Prev  Next

Rebuilding Ampico "A" Secondary Valves
By Pat DeWitt

Hi All,  I have several questions about my Ampico A secondary valves.
These are from a 1929 Mason and Hamlin RA (if that makes any difference).

- The outer recesses in the metal upper seats have a glued in "washer"
made from what looks like belly cloth material.  This washer has a hole
in the center which is only about 1/4" in diameter, thus effectively
reducing the hole size in the upper valve seat to the 1/4" size.

Is this to reduce valve noise?  I can only conclude that the smaller
hole size does not affect valve or pneumatic performance.  The valve
buttons are the larger 13/16" size.  (The entire valve assembly in the
stack is surrounded with heavy padded material which is obviously to
reduce the valve noise.)

- Also I have read and re-read Craig Brougher's detailed discussion
on rebuilding Ampico secondary valves.  Does adding a small circle of
pouch material under the lifter disc to limit the size of the glue dot
to the pouch improve performance?  It sure make for a neater lifter
disc attachment.  How thick (thin) should the leather circle be?

- Finally, I am using a machinist's dial indicator to reset the valve
travel to 0.035".  Is that good enough to achieve the best results for
a superior performing Mason and Hamlin Ampico A or should I use some
means of actually determining the air flow?  Does anyone have an air
flow measuring device that really works?

In closing, thanks to MMD advice, I now have PVC-E (a free quart sample
from the company, by the way), hot hide and Titebond liquid hide glue,
Phenoseal (which arrived last week in liquid condition despite the cold
weather), Hydrophane, and Union Rubber's #139 premium acid free best
test white rubber cement and #263 thinner.  I can now glue and seal my
way out of most any player problem!

My newest discovery is the absolute ease with which the liquid hide
glue can be applied and used.  It spreads like a dream and dries very

Thanks in advance for any and all secondary valve advice.

Pat DeWitt

(Message sent Fri 24 Feb 2006, 13:45:45 GMT, from time zone GMT.)

Key Words in Subject:  Ampico, Rebuilding, Secondary, Valves

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