It is about 3 degrees for every lb of pressure.....so if you have a 7 lb. cap you can add 21 degrees to 212 to get your boiling point...So about 233 degrees....
I had a very hot 406 sbc, that ran a little hot. a mech. friend told me to take the 160 thermostat out and try a 180, guess what, it worked on the chevy. why ? I don`t know, other than keeping the coolant in the rad. longer.????
