slow heating

[COPO 70 RS/Z28]

OK, Maybe someone has an idea,



Im pretty sure this is the factory set up. radiator recored, water pump ok, thermostat replaced, stock timing setting, clean coolant.

Problem: Sitting at idle the car will slowly heat, and continue to heat up very slowly, if I drive it will cool back down,

The assembly manual shows the setup as you see, assuming it is stock, any ideas?? It is now running a 180 standard themostat, oem appears to be 195. Assuming factory stock the system even though build without a shroud should run at the thermostate temp?? shouldn't it