Good Operating temp
 

I have a 1977 Pontiac 400 out of a Firebird. It seems to run hot. The timing has been set and it seems to climb up to about 210 degrees. What temp is too hot for operating?

It has a freshly cleaned radiator, new water pump and 180 degree thermostat.

Thanks in Advance

Thats gettin pretty hot. I dont like to see mine go over 200. Thats gettin pretty hot for a stock low compression engine.
Have you checked your jetting?
Also there is a mod the guys are doing with the new water pumps that are giving good results. Do a search for that, it should help alot.

My 1994 Olds has always run about 210 deg. My '66 Pontiac runs around 210 deg, but then I have a 195 deg thermostat.

I would not be worried about it.
Doug

210 is not too hot, but you could stand to lower it. stock timing settings were designed around emission requirements, not performance or comfort. you can try to add timing and see if that helps. the ported/full manifold vacuum advance still rages on. many things can help you lower your temps. make sure the basics are covered: coolant level, coolant flow, and airflow.

What are the specific timing specs?

Fan?

Fan shroud?

My Timing was set to factory settings. The manifold is from a 1969 (non-EGR). I have a 6 bladed flex fan and no fan shroud.

Enigine has a larger cam in it. I do not know the specifics, but I was told it was it is similar to the 68 HO cam.

Something I noticed was the oil pressure. At start up it is running a strong 60 psi. After the engine heats up the pressure starts to drop a little. At about 2000 RPMs after warm the PSI is only 40. Could the oil be thinning out too much and lower the lube factor and increase the heat?

I had a buddy that had this build on his 77 400 and he had the same issue. Hot Start and high temps. He added a shroud and it did not help his issue.

I appreciate any insight on this, the engine only has about 60 miles on it after being completely remanufactured.

Youve raised my curiosity. What temp would you expect for 11:1 compression? How much higher?

we need to know what 'factory settings' are for your timing.

You may have several issues here:
1 - you really don't have a 1977 engine anymore. With a more aggressive cam, older intake and higher compression you've duplicated the '68 specs. Go with '68 timing or just play with to a more advance state.
2 - no fan shroud IS a problem. The air needs to be directed through the radiator to cool properly. Do you also have the air dam below the radiator area? That deflects air up towards the radiator. Without it you will lose additional air flow.
3 - oil pressure will always be higher when cold. It will drop when the engine warms up. 40 psi at 2,000 rpm? Could be OK ... compare readings as the engine gets more miles.
4 - 60 miles since the rebuild? They are always tight when fresh which makes them run hotter.. Get some miles on it and that will help.
5 - someone else in this post mentioned waterpump divider plate clearance. The massive post regarding "chalk one up for the cat impeller..." is very long, but very informative. If you don't know the tolerance between the divider plates and the impeller I'd pull the pump and double check. Doesn't take much time when compared to overheating your engine.
6 - you have driven it 60 miles, but how much on the highway and at what speeds? Without a fan shroud your air flow below 40mph probably isn't very good.
None of the above will cost much money ... just time. Best to spend the time and research all possibilities before overheating your new engine.
Good luck.

I am going to get a shroud on it and replace the thermostat with a 160 degree high flow. I know that the water pump is not a cast one and there was some clearance between the pump and the plate.

What would be the proper timing for this engine? I can get that reset, and I hope that helps.

I have been running different speeds. The longest trp was to the NPD Octoberfest car show at Silver Springs this weekend. I had the heater on and the temp was about 190 th whole was there. After there it slowly moved up while in traffic and stopped and waiting. On the way home I was in traffic from the start and it got to about 205-210 before I got moving on the roads. It never came back down from there though.

You can try a thermostat, but that probably won't help. The thermostat is only there to get the engine up to operating temp. A 180 degree stat will open around 180 degrees, but the ultimate operating temp is controlled by other factors after that.
The timing should be set at 9 degrees at idle with the distributor vacuum advance disconnected (mechanical advance only). You may go as high as 12 degrees, but 36 degrees maximum advance at about 2,500 rpm.
190 degrees isn't bad, but 180 would be better. 210 is ok for a modern engine with aluminum heads, but not our old cast iron stuff.
The cast iron, curved vane water pumps work better than the stamped steel units. Pontiac never used the stamped steel ... these are rebuild replacements. You may need to go to several parts stores until you find a cast style. The rebuilders just use what they have available and four different boxes may have different styles. I'd try the shroud before doing the water pump. You need that anyway and it may be the total issue.
Air will go the easiest route ... kind of like water or electricity ... path of least resistance. If it is earlier for the airflow to go around the radiator instead of through it then that's what it will do. The shroud (and air dam) forces the air through the radiator. If you have weak air flow then once the engine temps get high it is difficult for the limited air flow to cool down the radiator.
I always go with the easiest, least expensive path when trying different corrective repairs. Try the thermostat if you want, then the timing, then the shroud and then the water pump ... rebuilds are fine and probably about $30.

No clue? And that was a generalization. Im sure it has to do with more than just the compression.
Maybe we could get someone to throw some shaved 400 heads on their stock 455 and see if the temps go up?

milwxman, good to see a local here. I'm west of ocala, I missed the NPD show, but went to the curise the day before. I agree with the shroud, also check the fan clutch operation. I'd say if it's staying under 210 in traffic your not doing too bad, I have trouuble w/ my '68 in stop and go, but at spee it's ok. tells me it's airflow speed it needs through the radiator, but I'm too poor to get a bettter leec fan. as long as it doesn't go over 210..... in my long quest for cooler temps years ago w/ this car, also found water pump spped to be a factor. while "parts swapping" you may have changed the water pump speed. although I don't use it now, when I had my electic water pump drive hooked up (1500 rpm ) the car ran cooler. FYI there's a few pontiac guys who come to a cruise at the dunnellon sonic on rt 41 every thursday at 6pm.

If you have an automatic 210 is TOO HOT
ask any 3rd gen Firebird owner. No offence meant, its just I hate to see trannys cooked.
keep in mind that a Thermostat rating is "static" so it doesnt FLOW full open till 9-10 degrees HOTTER than that rating. I would use a 170, or 160 if in the south.
A 170 flows full at 180@ roughly..
tranny fluid starts to cook at 200...

To expand on gtoformula here is what I have and run 170 all day long.

Manifold Vacuum with Vacuum Advance
9 initial
48 cruise
33 WOT all in at 2500rpm

Electric fans start at 180 and I have a 170 Thermo. I have a feeling your factory timing specs use ported vacuum and very little advance timing making the car run hotter than it should.

Get the shroud and do searches on here about the fan shroud, many aspects to keep an eye on concerning fan and shroud clearances/distances etc.

I want to say that the timing was set at idle to 12 degrees. Do you guys think this is too high and could be causing my extra heat?

most engine temps are taken from the head or intake by the water outlet. this is the hottest coolant temp in the engine. the trans cooler is on the outlet side (or cool side) of the radiator and usually 20 or more degrees cooler. if the engine is reading a max of 210, the tranny shouldn't be over 190, which is ok for an automatic. they came from the factory running this hot. :2cents:

I've read here that stock thermostat in pontiacs was 180-195 depending on year. 210 isn't too hot, but it's on the boderline. 215 makes me real nervous, 220 I'm looking to pull over, at 225-230 you risk detonation/boilover and 230-above is gonna blow a headgasket or crack a head.

I had a P350 that used to run 200-220 all the time. It hit 230 once and blew the headgaskets. I put it back together and it ran, but the rings were hurt and it started to get weak and lose compression.

Tuning is very critical on these engines and it would take paragraphs to explain it all in one post. I'll condense in a nutshell:

12-14* base timing, 36* all in by 2800 RPM
You need a 4-core brass radiator minimum, 2-core aluminum better
Cast-iron impeller waterpump with good divider plate clearance
fan shroud, high-lift flex fan or 7-blade stock fan and HD clutch
160-180 high flow thermostat and good hoses. 16lb radiator cap and puke tank.
25% antifreeze if in warm climate, 40% in colder climates
verify carburetor is not lean anywhere in fuel map.
Verify sparkplug selection and heat range and gap.

Low timing makes the engine run HOTTER, you can prove it with an EGT gauge as timing causes the EGT to go down. And usually your car idles more than cruising so running 8 to 12 degrees at idle is an easy way to heat up the cooling system on a Big Block. Modern era vehicles have this timing due to emissions, not cooling.

IF you have vacuum advance and an adjustable Mechanical Advance Distributor, I don't see the reason in running anything higher than 10 degrees initial/base. The higher initial timing will cause starting issues on higher compression motors and when the engine is hot and possibly heat soaking the starter. Ever since I went to this method of timing I've never had an issue starting after a long drive on my 11.3:1 compression engine.

I have 24 degrees of timing at 1200rpm, this will ensure that the timing is lowering the EGT at idle and reducing the demand of the cooling system. Those who lock out the timing at say 34 degrees will add they notice a HUGE difference in idle temps over their old Ported Vacuum setup.

So you are saying run 10* initial and 24* by 1200 rpm? If so how are you getting the extra 14* in just a few hundred rpm?

It's all in the combination and intent. While a full-race 496 might run great with locked timing for being consistant, a street 389 is gonna run like ***** with locked timing due to low RPM overadvance.

What works for me may not work for others. But I've found that running as much base timing as possible without starter kickback and then 36* total works best for my street/strip engines. The ideal is to have peak cylinder pressure at 12-14* ATDC, which is a function of basic physics, not choice. This means picking a base timing that approaches the ideal at idle, then lighting the mixture earlier and earlier as RPM increases. The rate of the optimal advance for any one engine depends on the parts chosen for that one engine and what that engine is asked to do.

Since a street engine is loaded by moving the car between 1000-4000 RPM, that is where we care what the rate and amount of advance is.

Check pump and cap; break in more.
 

I think it is too hot if your gauge is correct.


I am concerned about the pump. When you pulled it, did you note the condition of the seals on the two tubes that go into the cover? If you pull the pump, make sure they are in good shape and in contact with the divider plate. Jim Hand's book has some good info on optimum clearance for the vane and the plate if you want to check it. Get a good pump with the original large cast iron vane. If you pull a couple of inches of water out the ratiator and bring the motor up to 1500, there should be strong streams out of visible cores (with themostat open). Becareful, it may puke hot water on you when you close the throttle to idle.

There is a lot of good advice here for you on timing and such. I agee with all of these:
Go with a 180 or lower themostat (but after 200, yours should be open).
Set timing correctly.
Get a shroud on the fan; it pulls the air throught the radiator.
Make sure the radiator cap is good and break the motor in some more. The motor I just finished run hotter than I liked for a couple of hundred miles.

Last thought; I have gotten so many bad parts lately that I would not be surprised if it was a bad thermostat not opening up completely or a thermostat with too small of a valve opening (wrong application of a one all fits all unit). It is getting hard to get correct application parts as noted.


The 75-79 carbs were lean. Once you get it running cooler, you may like fatting up the power valve for more midrange power. The carb base gasket and intake carb plate are restricted and not allow the secondaries to open up completely. Easy to fix.

Hope this helps.

Apparently you're not running vacuum advance if you're wondering how to get to 24 degrees at 1200rpm.

I have 33 degrees WOT at 2500rpm, I then added 15 degrees of vacuum advance so while cruising, I'm seeing 48 degrees of advance around 2500rpm. I gun it at 3k just to make sure my springs have completely expanded by then. Great for mileage, cooling and response.

Good operating temps are 175 at least to 210.
You`ll prolly find that that engine will start to run cooler on it`s own as it breaks in and the new engine friction goes down.;)

Very valid points!
 

I like my cars set up for worst case scenarios. I like 160 degree t-stats. T-stats establish the MINIMUM temp the engine will be at not the maximum. I like to see my engine temps "around" 180 degrees. On a hot day stuck in traffic I don't want to start at 210. I don't see much of a buffer zone there.

I put a Mr. Gasket 160 high-flow thermostat in the car. Still have the same problem. Kind of expected it. I think that the engine is making more heat than the radiator can dissapate.

It is a three core. The car had an original 326 and this is the original radiator. What radiator did the GTO 389 or 400 come with?

Also another thought that was brainstormed was this is a 77 block and it was bored .040 over. It could be making more heat than the original radiator could handle. (Makes sense). SOOO I think that I might need to invest in a bigger radiator.

I just want to get this thing running without worrying!

Another thing, Could a bad damper pulley or wrong damper pulley cause this problem?

Pulleys
 

As long as the pulleys are stock Pontiac, they should be turning the pump at the correct rate. Boreing is not going to make it produce more heat.

It being a 326 car makes me think the radiator is too small. A three core is usually enough, but it depends on the size of the tanks and the area of the core. You can do some searches to see it this is the case versus a 389 HO raditor, but research won't make it run cooler. If you have good flow through the one you have and the motor is timed correctly, get a 500 hp aluminum to replace it. You can sell your radiator.

I am glad you are taking steps to cool off the motor.

When you get it running cooler, check the carb base gasket for a semi-circular secondary opening and a closed off top of your intake. Lot more power waiting for you...

My father-inLaw came over the other day and helped me time the car by performance. Seems that it was a ways off. Now that it is timed better, it seems to be running a little cooler. Took it out yesterday and stayed around 190 - 195 and jmped to 200 when on highway unning 75-80 mph. Temp dropped to 190 once I slowed down. The other factor is that the weather has been cooler too. Timing slipped a little again and I am going to re-timed and lock it down. I am liking the new timing. I think since I have the different harmonic balancer on it the timing lines do not match up right.

Thanks everyone for your help.

If your car runs hotter on the highway than all likelihood, you need a bigger radiator. In every instance when I had that problem, a bigger radiator solved it by running cooler.

All pontiac V8's used 195 stat's since 66.
210-215 operating temp was/is normal.

On newer cars e-fans dont kick on till 230-240.

The higher thermostat temperatures are one way that automakers were able to reduce emissions to meet the ever tightening EPA regulations and this move was not done to increase horsepower. This is one reason why many ECM upgrades (for performance use) include a low temperature thermostat, like the 160° for many LS1 applications. Here in Central California, the 160°F thermostat is perfectly adequate and that is all we have ever used. We actually saw a HP reduction on the chassis dyno on one of our oval track cars when we elevated the coolant temperature, so we never went back.

Someone mentioned earlier in this thread that the cooling system is a combination and they hit the nail right on the head.

When I run a Robertshaw 160°F thermostat and 7 blade, 17" Lincoln Flex Fan on my 1975 Formula, I cannot get my coolant temperatures to go over 185°F even in traffic on a 100°F day. However, when I ran a AC-Delco Severe Duty Clutch and 7 blade fan, the car ran 190°F going down the freeway and over 200°F in traffic. The fan clutch effectively regulated the coolant temperatures.

You could actually hear the clutch fan 'lock up' or apply a little over 200°F and then 'kick off' a little below 190°F.

I will post photos of the temperature gauges (verified by a SW mechanical and infra-red gun) on a +100°F day to this thread later and the difference is remarkable...Robert

I have an usual Pontiac. If I run a 160 thermostat, it runs 160. Everywhere. 195? Same thing. I like a 180 in my car.

Results Vs. Theory:
 

Here are the photos:

Photo #1:

+100°F day 75 mph with 7 blade fan and AC-Delco Severe Duty Clutch

(I also tried a Hayden Severe Duty Fan Clutch and it also kept temps up around 200°F all the time.)

Photo #2:

+100°F day 75 mph with 7 blade Lincoln flex fan

(The car will not ever get any hotter than this, even in traffic, verified by mechanical guage and ray gun.)


Note reduction in oil pressure in photo #2....Robert

With adequate cooling sytem capacity, a good operating temp is one that is within a few degrees of the thermostat rating...

[QUOTE=Region Warrior;3809802]All pontiac V8's used 195 stat's since 66.
210-215 operating temp was/is normal.

Wow, what a laundry list! Thermostats dont change NORMAL engine operating temps. Thats why when you install a 180 thermostat. The temp sooner or later approaches 200-210. The exception to this is a car that runs a certain temp without a thermostat. As to 210 being too hot, that is normal. For the transmission 210 is hot, thats why they have a cooler installed in the radiator on the return side. You may have serious problems if 210 is the temp of the coolant entering the water pump. Also ask yourself this: if 210 is too hot, why is it in the middle of most guages in mid 60's to late 70's Poncho's? Just my two cents!

Thermostats set the MINIMUM operating temp nothing more nothing less.

Not to rain on your parade, but that's no big deal because you're not running a/c. I run a non thermal clutch in my 72 Formula with a/c. Without the air on, the car will run 170. With the air on and in traffic, it'll get to 210.

Please don't take this the wrong way, if had a temp gauge on my car and it was constantly running at 210 or above, I'd be looking to bring the temp down too. But as my current ride, a '72 Grand Ville, has an idiot light, I run it in the middle of summer in heavy traffic with the A/C on brrrrr and don't give it a 2nd thought - the 'hot' light hasn't come on yet and I'm pretty sure it works.
On the other hand, when I had my '66 GTO with a tri-powered 455, even though it didn't over heat, I had my eye on the temp gauge constantly.

What BonneVista said. Around here an idiot light is the way to go on the street. LOL

your running a flex fan and no shroud? thats part of the problem. A hotter cam in a low compression motor, thats part of the problem.

later cars runn hotter because its engineered that way to assist in emmissions polution controls so thats not relevent.

you replaced the pump and the radiator but did you flush the engine cooling system at all? and at any point did you drain the cooling system and let all the rust,scales and debri inside the cooling system dry out befor you reinstalled the antifreez? taht stuff when its dry's out becomes hard as cement and almost no amount of flushing will remove it. Thats a no no. Too bad you replaced the water pump and radiator as I would recomend putting a little draino in the water and running it up to temperature befor flushing the system. Draino is very bad for water pumps and radiators but its effective on rustand stuff like that. a little red nechish but it works. But I cant recomend it after you installed a new rd and pump.

Rethink the cam and check your entire ignition system from the balancer to the vacuum advance and mechanical advance. If you installed new plugs of the same heat range that should not be the problem but if you changed the range that could be part of the problem. Also with the hotter cam in a smog motor do you know the condition of your cylinder heads in terms of oil usage and carbon build up? all of these are factors.

326 3 core radiator should be able to handle what you got , especially cleaned out. Other posts are talkin rebuilt this and that but Idid not see that in your first post. hot cam in a 30 year old motor is askin alot. what did you do to the carb to compensate for these changes? Dual exauste on a smog motor will cause it to rune a bit too lean , more so with the hotter cam

re
 

Aluminum radiators are your friend. I would look into a radiator and shroud. What is the minimum temp you guys think a pontiac should run at? Is 160 too cold? I was allways under the impression that the cooler you could keep an engine the better it ran?

I ran a cheap aluminum radiator/clutch fan and shroud in my Nova. I had an 11.1:1 compression high winding 350 running 89 octane and at Car Craft summer nats in 05' The actual temp was north of 100 degrees with a load of humidity. The car never cracked 180 degrees the whole time i was crusing and i never had any detonation. Unless a car is strictly a numbers matching show piece i would run an aluminum radiator every time. Theres almost no better upgrade you can make.

a cooler intake charge is a good thing, denser air mixes with more fuel to do more work. but inside the comustion chamber heat...doing work ...up to a point is a good thing. mess with fuel, cams or chamber design and things begine to change.

combustion chamber temp and water temp are not the same thing.

aluminum radiators are not the do all end all solution to hi water temps

its usually cheaper to fix whats wrong