Is there a hi-temp expanding foam on the market?

Hello,
I have a small hole in the exhaust manifold right where it attaches to the
engine -- actually a small piece of the gasket is missing. There's a
little
space in there that would seem ideally suited to accept a dollop of foam.
The foaming insulation at  the hardware store can only deal with temps
below
200 degrees. Is there anything out there with a higher temp rating?
(JB Weld works okay, but doesn't seem to last)
Thanks!!!!
Fred