[Healeys] Heat shield material advice needed--NON Healey

[Awgertoo at aol.com]

I have made a sheet metal heat shield that goes between the tubular  header 
and the carbs on the MGA engine in my Elva and would like to back it  with some 
heat-insulating material.  I know that folks have used various  construction 
materials such as Hardy Board to replicate the original asbestos  panels on 
the toe box and firewall but I wonder if it is actually a good  insulator?  Any 
opinions will be appreciated.
 
Best--Michael Oritt
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