I have a 1989 Camaro RS 350 let me give you guy’s some backstory and variables to help me troubleshoot my issue.

Originally I purchased this car as a 350 5.7 with a Edelbrock carburetor It came with a aluminum radiator and dual 12” fans not sure of the CFM but it kept the engine cold in Indiana summers and kept it at 180° at all times. The engine was a 3970014 or a older 350 4 bolt main from a Camaro Z/28 had a bad camshaft and bad crank bearings so we swapped it to a 89 Sierra 2 bolt main 350 that was practically new and worked awesome.

This is the part that gets me stressed I swapped everything from the 4 bolt to the 2 bolt and every thing works awesome it runs good no bad gaskets no bad nothing. Over the winter I did a cooling overhaul and got a new 180° Duralast Gold thermostat and a new Duralast HD water pump and a new heater control valve. However this time my cooling results changed back then it would average 180°-185° and now it averages 190° with the climate control switched to hot but the climate control doesn’t have to be on and 212° when it’s at the cool side and climate control off my question is why did this happen If it never did this and everything is exactly the same? It’s the same radiator same fans and same but new water pump and new thermostat. What could cause this I was thinking maybe it needs a new rad and some better fans then these chinese fans?

 

What happens if you put the old thermostat back in? I'm suspicious they are not the same.

 

Was the block flushed forward & backward. there is really nothing wrong with 190* in this engine. Did u check the thermostat in boiling hot water to be sure that it would completely.

 

Sounds like the thermostats aren't the same. As mentioned. 190 is not hot.

 

Remember, a 180* starts to open the but does not fully open until 190*