It's function is a stop to allow the valve plate inside the manifold to be
parallel to the airflow when the bi-metallic coil is relaxed. You could
use almost anything to accomplish the function. The asbestos is to pad the
sound. The only penalty you might pay is a rattle some of the time.
I think that I used a piece of the high temperature silicone rubber from the end
of a spark plug wire on my car. (OK, purists, you may emit a collective
"Shudder", now.) ;-}
Joe
Savard
Lake Orion, Michigan