mancat wrote:
There's some sort of strange plastic gasket that does basically nothing - I'm guessing it's just a phenolic spacer/insulator.

Insulator is correct. "Does basically nothing" is incorrect. It keeps the heat of the engine migrating up the intake to not affect the carb temperature. Without it you'd have a lot of heat issues in the carb.
  

Paved roads, just more needless government spending...

I pick up my mail in Santa Barbara, California, USA.