ok so me and my friend just dropped a new 350 in my 87 firebird. the problem seems to be that when im sitting still its only gets to about 210 and then i can see the gauge drop. however when i take it for a drive it starts to get hotter and hotter. then when i put a load on the engine like going up a hill or going from a stop the temp rises. it has a new waterpump and thermostat. could this problem be related to the radiator you think? thats the only thing i havent replaced yet.

what do u mean it gets hotter and hotter? if its rising above 210* then i would say that u dont have your air dam installed (the little horizontal piece of plastic that connects beneath the radiator.) If it heats up to 210 then stays constant or cools then u should be fine. If your really concerned throw in a 165* thermostat. Do you have an engine driven fan or electric?

ok so this is what i did when i drove it home last night i noticed the temp was at 240 and slowly climbing. so i thought maybe an air bubble in the lines somewhere. well when i was checking it earlier today the temp would not get above 210 before it would cool down to about 190 or so. then when i was taking it for a drive the temp would climb back up to 210 and stay there thenafter about 15 minutes of driving go up to about 225 and would go below that. when i would put the car under a load ie going uphill the temp would climb rapidly and going downhill it would cool slowly. when i got the car i never noticed any air dam in the front at all. that may be it though i'll look it up. thanks for the suggestion.

so i just got a new (picked up at a juck yard for 5 dollars) air dam today, mounted it and test drove. So far so good. my temp only gets to about 215 while im driving but it slowly rises to just about 230 as soon as i shut the car off. so within the next couple of days if everything goes ok i guess i have to update my profile.