What is a temp. that GM designed my 89 Iroc Z 305 TPI to run at?
i am running around 229-238.....sometimes higher(243)
the boiling point of a 50/50 mix of coolant to water is 265 degrees....I am really worried

 

The engine was based on a 195 average operating temp. With electric fans GM allowed the temp to go to about 222-225 degrees before turning on the primary fan. The secondary fan kicks on at 238 degrees. On a properly operating TG the primary fan should keep the temp on average around 210-215. I cannot say this enough, the most common cooling problem I run across are intermittent fan relays. The primary fan relay gets the most cycling hence it fails more. When it does it allows the engine to go to 238 and that's when the secondary fan turns on. Replace both relays before doing anything else. There was a design issue with the original relays. The newer design indicated by "made in China" is a totally redesigned unit and better mechanically and electrically. You can get it from NAPA under thier part # AR-279 for most late TG's. Don't mess with manual fan switches or lower turn on temps for the fans. It is not necessary and won't solve any problems. Constantly running the fans or lowering the temps so they run more often just chews up the relays and will cause premature failure of the alternator. GM designed it correctly and took into account all the variables to insure reliability of system components. Otherwise apply cooling system troubleshooting to any other problems. You can if you want run a 180 stat, it should not affect engine operation since average temp in modern driving conditions will still be around the target 195 area. I run a zz-4 block with all STOCK cooling components, 195 stat and stock fan turn on temp. It rarely gets above the center of the guage even under the worst conditions.