Him everyone,
I Googled some more info. From this I determined:
Nylon = polymide
Nylon is good to 100° (212° F) or a little more (110° C )
Now this doesn't mean that high temp nuts don't exist. If you think about it, the lower valve cover nuts must get pretty hot next to the catalytic converter so I'm still confident of finding some. Maybe a different grade of polymide?
Let me know if you guys know or find out anything more.
"Bollhoff Seal LockÒ Sealing Nuts
Seal LockÒ nuts are pressure tight, self-locking and reusable. They are
temperature resistant from -40° C to +110° C. They can withstand high gas and fluid pressures making them well suited for hydraulic applications. Seal LockÒ nuts can be fed and assembled automatically and require no special preparation of the seating surface. The seal material is
Nylon (Polyamide 11) and is impervious to oil and solvents."
http://mdmetric.com/bollhoff/seallock.htm
"Self-braking nuts with polyamide insert
The top portion of the self-braking nuts with
polyamide insert has a special, built-in
polyamide 6.6 technically-sized spring washer.
...
The
self-braking nut with polyamide insert maintains its properties within a temperature range of -40°C to +100°C.
Above 100°C it is recommended to use metallic braking nuts or those built with a metal insert.
http://www.da-tor.it/ing/famiglia1.htm
thanks,
Chris