I have an 87 Firebird Formula 5.0. What is the engine temp before the cooling fan comes on. I have let go up to 220 and it still doesn't come. I have changed the thermostat, fan relay and temp sensor.
Also, after idling for a short period of time and the temp is only like 180 I get boiling or bubbling in my overflow tank. Any suggestions and thank you for your time.!

Rob in Harvest, Al