350 Chevy operating temp

[akdsmer]

-Interior cab heat is a product of the exchange of cold outside air and hot coolant. You don't get much better than 150* at the vents with 195* and shop air, you can bet that 100* air out the vents is only warm when you have -40 air pushing through the core. If you drop the engine temperature down to 150*, you will be lucky to anywhere near that with a good heater core.

-A fan pushing -40* air onto the engine is a very good heat exchanger. I would replace the fan with the correct fan. Most likely this will fix your problem. Same thing happens when the thermostatic clutch fans go bad.
I would remove the fan and see if the engine will then maintain temperature. If it doesn't, then replace the thermostat. I don't buy my t-stats from the aftermarket. I get them from the dealer. Even then you can get bad ones-a typical failure is a bad spring that won't keep the valve closed, or an aftermarket pump/pulley that has higher volume/pressure than stock.

-It doesn't take a sophisticated computer to see that the engine temperature is getting too hot and then pull timing and add fuel (to cool the cylinders). But this doesn't happen at 205*. The only real computer issue is that many times a 160* t-stat will keep the vehicle from going into closed loop on pre 1996 engines, as it is waiting for it to warm up. this also throws codes on FI vehicles for not reaching operating temperature.Regardless of the temp of the t-stat, it is suppose to keep the engine at the set temperature, so keep the 195 that came with it and ditch the cheesy fan.

I've had a couple of early 90's TBI trucks. They all made good heat and kept at or near operating temperatures when it was cold, although one wanted a few more rpms to flow enough coolant through the core to make great heat.