Did you build the engine? Do you know what Cam is in it? a friend here in town has had 3 yrs of running hot...he bought a rebuilt crate Pontiac 400 8 yrs ago, finally got it in the car 3 yrs ago...since then it always ran hot ,he tried everything, thermostats , fillers , big radiator, rebuilt tranny, etc ,etc...two weeks ago he bought and installed a stock cam...runs perfect now ...190F on our cruise to Corpus in 90F weather...