1991 C4 will not start after warmup
 

Not only will it not start it won't even engage the starter, nothing. Let it cool down and it's good to go. Battery is fine, starter works well but like many Vettes it gets really hot but does not boil over. Any ideas? Stumped my mechanic.

How is the exhaust routed on a C4? My C3 had long tube headers and an inadequate heat shield around the starter. I had the same issue until I wrapped that portion of the headers.

Sounds like heat saturation in starter field coil...
Replace starter.

Pipes are wrapped, exhaust is wide open as cats are gone, probably a shield on the starter or a new one would probably help.