How hot is too hot?
 

I have a 68 Firebird with a 400, an all stock cooling system such as a belt driven fan, stock fan shroud, and standard type water pump. Over the winter, I completely flushed the coolant system and added all new coolant with a 50/50 mix of water and anti freeze. I also installed a brand new thermostat with the stock rating of 195 degrees.

I've noticed that my car likes to run warmer than most of my other cars. It always seems to hover around the 200 degree mark. Last night on the way home from a cruise night it hovered around 210. I will grant that it was a very warm day here yesterday and I understand the hotter coolant temp but I'm usually used to my cars hanging out below 200 degrees.

I was talking to a guy at the cruise night last night who described something that only 400 Firebirds came with which are coolant block off plates for the space between the rad support and the grill area. He said that they direct the flow of air more into the radiator as opposed to over the rad and into the engine compartment. I thought I'd try that and see if it works.

Any suggestions or am I nuts for being worried for temps hanging around the 200-210 degree mark most of the time??

Normal temp would be approx. 190. Higher engine temp makes the engine ping easier.
Have a look at the "give one upp for the cast impeller" thread sticky above. See to that you have a good thermal clutch, good fan (19" high pitch seven blade), shroud and the waterpump mod. That made it me.

400 & a/c. birds had them , also make sure you have the lower valance air pan on as well . My 68 with a 400 has all of the above & on a 90 degree day it can sit in traffic indefinitely and never breaks the 190 mark .

radiator baffles
 

i agree with chris. The upper baffles and lower air dam are critical as well
as water pump clearancing and good HD fan clutchwith & blade fan.
my car with 180 stat this weekend never broke 190 except when I was stuck in traffic after getting off highway. Climbed and held at 195(highest) and dropped right to 185 once moving again. I am running the factory style 3 row radiator.

water pump pump pulley size is a player too. Mine takes longer to heat up with the
smaller 6" pulley but also cools better.

Gerry

And if the temps don't come down with the mods mentioned, remember that 210 degrees is no problem whatsoever on hot days.

:2cents:

Don't believe them your engine is in danger if it's running at 210 deg's. Older enginge are not designed to run those high temp. Newer engine run that high because they were/are designed to run that hot & have the ECM control the fuel flow to help cool them down when they get to hot. Thats why a new car will smell as if there some gas coming from the exhaust when they get to hot. , also the timming get retarded . But haveing an old bird run at 210 is way to hard on them. They were designed to run at 185-190 only. If it' didn't go down when your running in traffic you have a PROBLEM. Start by checking your timming & then adjust your carb. You need the extra fuel at idle to help keep it cool. Also to advance on the timming will make it run hot. To little fuel will make it run hot. Your 400 should be able to idle all day long at 185 with a 2 row rad. Even in Hot weather it should not go above 190. I'd look at the items I mentioned first before you go spending any big money on items you don't need.

I would start with confirming that your tempgauge reads correct then go thru the list above. It might just be so that tou have an incorrect reading as the temp was stabile at 210.

Had my '72 LeMans out this weekend in 90ºF weather and it would run at 170ºF cruising and 180 idling at a light. I have the stock 3 core radiator with the water pump clearanced and a 7 blade flex fan. It used to go uo over 200 with a Hayden severe duty clutch and factory 7 blade fan. I use a 160ºF high flow T-stat.

I'll 2X that-Also may be the temp sender. The more anti freeze the harder it is too cool. l always run 160 T Stats To be old and wise you had to be dumb and stupid

I might be wrong but at a 50/50 mix with antifreeze you will actually get a higher boilingpoint, this together with the overpressure in the system will move the boiling point up to about 120 C?

A 50/50 mix of ethylene glycol/water boils at 225ºF at atm pressure and 265ºF at 15 psi. The specific heat of pure water is about 20% higher than 50/50 so you will need 20% more flow with a 50/50 mix to be equal to pure water. Pure water transfers heat better than 50/50 glycol.

THANKS AG I was talking about heat transfer like you said.

I have to ask...why is it surprising to see 200+ degrees when you have a thermostat that doesn't open until 195 degrees? Try a lower temp. (ex. 180) thermostat and see what you top out at. I'd think you wouldn't see much more than 195 in traffic. Easier/cheaper to try that first than spend big $$ chasing it.
I might be missing something here so let me know if my reasoning is off.
Dave

If your factory spec'd thermostat is designed to open at 195* then 210* on a hot humid day with A/C on (some cars have A/C and still take a 195* thermostat)would not be unreasonable. Don't forget a lot of our ponchos have the temp sender in the head. Is that the most accurate place for the sender? Is it there for economics? Is it there for assembly line purposes? Does it matter if its in the coolant crossover? You get the idea. Oh, and lets not forget that our gauges are mass produced. Food for thought.

The best place is in the head as it will give you the best & most acurate temp reading in the spot that gets the hottest. Most of our cars came with a 180 temp t-stat & back in the day we all used the 160 tamp t-sat because a coolengine is a better running engine. New car enginges run hot for emmisions only , they make them run that way but it is NOT the best thing for the engine.

Don't listen to anyone that says 210 is to hot.
That's what they ran from the factory.
Think GM didn't know what they where doing?
The more heat an engine can tolerate, the more power it will make.
Anyone that says opposite doesn't know thermodynamics.
If it pings, theres a problem with the tune and/or fuel.

FWIW, back in 75-79, my 1st FB ran low 11's and got to 220-230 in 90* heat.
Just 4 blade fixed fan, shroud, and valance.
If it over flows, the level is to high. Most people think the radiator should be full when cold like todays cars. Wrong.
If it pings, its the fuel and/or tune.

I had a little bit of hot until I fixed my timing issues. At least 6 degrees more initial, and replaced the vac advance with one that actually worked.

I'd rather see my temp hover at 210 than 170. Too cool is damaging to the engine over time due to the contaminants in the oil....like gasoline and water vapor that will remain unburned at low temperatures. It takes heat to vaporize that stuff and get it out of the oil.
I don't even worry about it at 210...but that's just me.

Good point Greg!