[71SportRagtop]

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??

[A.J.]

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.

[chrisp]

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 .

[68 Firebird]

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

[Mister Pontiac]

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

[rexs73gto]

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.

[Region Warrior]

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.

[FrankieT/A]

Originally Posted by Region Warrior

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.

Region Warrior is 100% on the mark!!! Pontiacs do run too close the border of the over heating they withstand in my opinion. Some engines can get seriously over heated and be fine after cool down. Pontiacs are not one of those engines! Pontiacs do not like to be overheated. For one thing as an example, Pontiacs have four head bolts per cylinder whereas Chevys have five. IIRC Chevys also have more bore spacing which gives more deck surface area between cylinders which obviously gives more head gasket contact area. Hotter engines make more power and are more energy efficient, and that is a fact. Problem is with Pontiac that starts to approach the catastropy point. At the expense of power and efficiency I like my cars to as cool as possible because I like the cushion. I like my cars to run as far below 200* as possible. It makes me feel better. Predetonation is a matter of tune, but so is hi compression. Low compression low performance engines do by virtue run cooler.
So how hot is too hot? Depends on a lot of things.

[Region Warrior]

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.

[Squidward]

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.

[Greg Reid]

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.

[Region Warrior]

Good point Greg!

[rexs73gto]

Reigion warrior must be a kid , because there were no Pontiac's in our years that came from the factory that ran at 210 dg.'s. If it did it would have went right back in to be repaired. Our year cars were ment to run at 180 deg.'s & maost everyone in my day put in a 160 or 165 T-stat so they could cruise all night without their car getting hot & having to pull over & stop. The only time Pontiac made cars to run anywhere close to that was from the late 80's when they started to use computer in the cars & then it was for emmissions & not real world performance. If you had a car that ran that hot we started to look for broken parts when they were brought into the dealership for service. Plue the 195 deg. T-stat wasn't even available for use in our cars when they were new. The T-stat that was in my 73 GTO when I bought it new was a 180 deg. & that was to much when we started to run them hard as they got TO HOT very fast. So before you start saying it was made that way , please check all your facts against real world usage first.

[A.J.]

Hmm, this seems to be a sensitive subject?
To the help the threadstarter sort this out I would say he would start checking the simple things
1. Confirm that the gauge reads ok
2. Service the engine, see to that the timing and vaccum advance is working and correct. Check for vaccum leaks, check the sparkplugs. Check the thermoclutch by spinning the fan by hand. It should not continue to turn by itselft more than 1/4 turn if its good. Are the hooses ok and do you have the spiral protecting the lower cooler hose from collapse?
3. Also see to that the carb is adjusted/calibrated.

If all checks out OK but the temp still is high its time too look at what type of faan tou have, waterpump cast or stamped impeller, waterpump mod.

How is the compression of the engine?


I'm no expert and I just been walking a year when the car in question was made but the above makes logic for me and any comments to the above is appreciated

[Region Warrior]

Ok, simmer down
Didn't mean to get ugly. This topic comes up every year since the 70's(for me).
Grew up in new 60's/70's Pontiacs and 1st car was a 68 FB from 75-82, and have a 67 since 79.
All my buddies had muscle cars. They all ran over 200*.

Been to Arizona(brother inlaw lives in Phoenix). And Death Valley in 65. Never forget it.
7 of us in a month old 65 Bonny full of luggage and A/C full blast. 115* out at the time, dad was concerned cause temp gauge was pegged most of the trip.
Us kids where complaining how cold it was in the car. After 5-10 minutes of it, he pulled over and made us get out for 10 minutes(felt lot longer lol) while he and mom in the idling car stay'n cool.

Wouldn't necesarly call 11.70-12.00 @ 114 mph with 3.42's on 87 octane in 95* heat detuned. And also drove it 70 mph plus for 20 miles in 95* heat more then once.
Most guys think its overheating when radiator over flows.
Cause is usually aftermarket stuff and/or missing factory stuff.
Or radiator full to cap when cold which is incorrect. should be 1.5"-2" below.
Don't take this wrong. But since you dont believe they ran that hot back in the day, check 60/70's factory service manuals and road test articles from the 60's and 70's.

[Chris65LeMans]

Originally Posted by A.J.

Hmm, this seems to be a sensitive subject?

It definitely is. I'm new to Pontiacs, but talk to a lot of the Pontiac guys at shows. Opinions run from both sides of the spectrum; from "My car runs at 160 going through Death Valley at 110 mph and 120 degree heat with the A/C on" all the way to "sure, it gets up to 235 at stoplights, but drops again when I start moving."

Mine will see 220 occasionally in stop and go traffic if I start lugging the engine (I've got an M21 and am trying to break my habit of using too high a gear at low speeds.) As long as it gets below 200 once I start moving again, and doesn't rise above 230-ish; I'm happy. I run this past Pontiac guys, and never hear any alarms.

I see guys on here all the time throwing money and time at their car so that their temp needle NEVER moves off 190; and I'm not sure that's a realistic goal. (particularly on a car that came stock with a 195 'stat.) There's always other car stuff that time and money can be used on.

The owners' manual only had one line about heat. Something like "if it ever gets above 245, shut it down and see what's wrong."

[FrankieT/A]

Originally Posted by Chris65LeMans

It definitely is. I'm new to Pontiacs, but talk to a lot of the Pontiac guys at shows. Opinions run from both sides of the spectrum; from "My car runs at 160 going through Death Valley at 110 mph and 120 degree heat with the A/C on" all the way to "sure, it gets up to 235 at stoplights, but drops again when I start moving."

Mine will see 220 occasionally in stop and go traffic if I start lugging the engine (I've got an M21 and am trying to break my habit of using too high a gear at low speeds.) As long as it gets below 200 once I start moving again, and doesn't rise above 230-ish; I'm happy. I run this past Pontiac guys, and never hear any alarms.

I see guys on here all the time throwing money and time at their car so that their temp needle NEVER moves off 190; and I'm not sure that's a realistic goal. (particularly on a car that came stock with a 195 'stat.) There's always other car stuff that time and money can be used on.

The owners' manual only had one line about heat. Something like "if it ever gets above 245, shut it down and see what's wrong."

My car sees thousand mile trips(last one was two weeks ago 2000 miles round trip)and the last thing I want is a blown head gasket far from home. So, yeah, I need that comfort zone!

[rexs73gto]

My 73 has been running a bit hot of late & just this week I tore it down & put in a new water pump. I was running at or about 200-205 while in traffic & a little higher when at a stop. That has been the way it's run since I put in the new engine. I now have a 461 in my car & with it running hot like that I thought it was because it was a brand new engine. But no , there was something else going on so I pulled it apart & clearenced the divider plate to somewhere between 25-30ths. as it's very hard to get an excact measurement on the fins of the blade with the plate in place. I have it all bace together now & took it for a drive yesterday. I forgot to say I put in a 160 deg. T-stat too, it now runs in between 170-175 degs. while sitting or driving now. Thats where it should run no higher if you want them to last. I forgot to clearence the divider plate the last time & I think that was my biggest problem , but it runs where it should now. For all who are having any cooling problems don't do as I did & forget to clearence that diviver plate it is a must to do on our Pontiacs to make them run where they should.

[Region Warrior]

Originally Posted by rexs73gto

Reigion warrior must be a kid , because there were no Pontiac's in our years that came from the factory that ran at 210 dg.'s. If it did it would have went right back in to be repaired. Our year cars were ment to run at 180 deg.'s & maost everyone in my day put in a 160 or 165 T-stat so they could cruise all night without their car getting hot & having to pull over & stop. The only time Pontiac made cars to run anywhere close to that was from the late 80's when they started to use computer in the cars & then it was for emmissions & not real world performance. If you had a car that ran that hot we started to look for broken parts when they were brought into the dealership for service. Plue the 195 deg. T-stat wasn't even available for use in our cars when they were new. The T-stat that was in my 73 GTO when I bought it new was a 180 deg. & that was to much when we started to run them hard as they got TO HOT very fast. So before you start saying it was made that way , please check all your facts against real world usage first.

Funny you say kid since your wrong on several points.
Not gon'a point'm out, but if their meant to run 180, why did Pontiac only install 195* stats all models from 66 and up?
Have you ever replaced an original stat?
If it was anything less then 195, wasn't original.

[importsmasher]

Pretty much every Pontiac I have ever owned ran around 210 degrees. My 66 GTO convertible ran 240+ all day long in the Arizona heat until I put in an aluminum radiator. I ran it like that as a daily driver for many years and the engine has almost 100,000 miles on it since rebuild, still running strong, with no issues from running hot (it's not nearly as hot here in Utah, and it runs 210 with the aluminum radiator). Not Pontiac, but my brother has a 69 GS that he ran a 430 with A/C as his daily driver for at least 8 years that also ran 230-240 all day long. He has since replaced the engine, but only because he wanted a correct 400 in it. Even the 62 LeMans I had with the aluminum Buick V8 ran 200-210.

I don't give anything under 230 a second thought. That being said, the engine I just built for my 73 Formula seems to stay in the 190s...

Flame on....

Importsmasher