210+ at idle : (
 

The problem child – 1972 C3 LS5 / 454 …. thanks in advance for the help.

The bad – High temperatures (hits 210+ with the A/C on) when idling.

The good – Stays cool at highway speeds. 40mph or more, it cools down to 190 estimated, even in Alabama 90 degree heat. Not losing any coolant.

What’s been done:
- Radiator has been taken to a capable shop and cleaned / tested.
- Expansion tank (aluminum) has been repaired (welded pin hole).
- Radiator fan shroud seal kit and radiator support seal kit have been installed.
- I’ve tried a 180 thermostat, a gutted thermostat (removed everything from the “ring” and even drilled holes in that), and no thermostat and it still gets climbs to 210 at idle. The 160 thermostat is currently in the car.
- I drained the coolant and refilled with 80/20 water/antifreeze with Water Wetter. Still 210, but it seems to cool back down quicker at driving speeds.
- The fan clutch seems to be working correctly. Even with the engine hot, I can turn the fan clutch by hand.
- I replaced the water pump, which did not have an effect on the problem.
- I used an infrared thermometer to verify the temperature at the water neck matched the gauge, and it’s within 10 degrees.
- Several different timing setting have been tried, and based on the timing light and header temperatures, I think I have it set ideally.
Equipment – Original A/C car, but currently running Vintage Air A/C, Aluminum expansion tank, original radiator (copper), 160 degree thermostat, RC-15 expansion tank cap, lower radiator hose has a factory looking metal tube (which cannot collapse), new water pump.

Questions –
- Did any 72 model big block cars come from the factory with an aluminum expansion tank? Mine has one.
- With the aluminum expansion tank, does it need the RC-26 expansion tank cap or the RC-15 expansion tank cap?
- What is the difference in the RC-15 and RC-26?
- The carburetor (original) has two small vacuum ports, both pointing toward the front of the car. Did the car come from the factory with the vacuum advance attached to the port on the driver’s side of the carburetor or on the passenger’s side of the carburetor? I’ve tried both, but the car still gets hot. Attaching to the one on the driver’s side of the carburetor makes it run rougher, so I’m guessing it has more vacuum pressure.
- Will the chin spoiler (or absence of it) affect cooling at idle? If so, why?

My '71 owner's manual states that 210-215 is normal operating temp. You may have it as good as it gets with the factory parts.

I didn't like the high temps and installed a BeCool aluminum radiator & Spal electric fans. Stays at 180F now.

:iagree: Yup. You're trying to fix what's not broken.

Just called a friend of mine with a '72 C3 LS5...

Asked him what his temp is at extended idle with the A/C running.

He immediately said, around 205 to 210!

Hi marc9889, I have a couple of suggestions. My 77 - L-82 used to operate as a normal temperature of over 200, I believe the stock thermostat was a 215.

I thought it was too hot but I think the L-82 engine was designed that way to allow for the smog heads and produce less emissions. With that said my engine is no longer the stock 350 so I have upgraded the cooling system to a Dewitts rad and dual spal fans.

The two items that I would recommend for you is possibly the use of dual spal electric fans and also a high flow thermostat if applicable.

When I added my cooling system I originally went with a standard 180 thermostat but I have a high flow Edelbrock water pump. The engine ran quite hot and the electric fans turned on quite often, so I replaced the thermostat with a high flow 160 and the engine runs much cooler now.

Hope this info. helps.

:thumbs:

Since you have aftermarket air, why not put that copper/brass radiator in the box that your new Dewitts Direct Fit aluminum radiator comes in? You reportedly can see up to a 30% improvement in cooling.

Also, are you sure that your fan clutch is working properly? It is supposed to lock up as it gets hot.

I am not familiar with the '72 BB cars. Do you have a front license plate blocking some air flow? Is all the air being directed thru the radiator core, or are some of the air dams and seals missing?

Like posted nothing wrong with your car
For a BB w/ac idling on a hot day esp in a compartment like the c3 210 is doing real well. It wont hurt a thing.

Yep, like my pappy used to say..."iffin' it ain't broke, don't fix it".

Thanks for all the responses, and they back up what I have been reading elsewhere – that 210F to 215F isn’t dangerous for the car. I don’t disagree, but like zwede said, I just don’t like the temps that high. The 180 he mentions is much more to my liking than 215F, and my car performs much better at 180F than 215F (not to mention the heat I can feel on the floorboards, etc). I’m also inclined to believe that the higher temps reduce the lifespan of rubber bushings, plastics, and some electrical parts, so there are plenty of reasons to pursue keeping it cooler. If I can’t get there with the factory radiator, that’s good to know.

Front license plate – no. Fortunately in Alabama, we aren’t required to have one. Unfortunately in Alabama, a high percentage of the general population wears overalls and plays the banjo. I’m joking. It’s actually a great place to live.

Dewitts Direct Fit aluminum radiator – probably. I’ve tried just about everything else, so I’ll probably order one shortly. All the seals are there, but the chin spoiler is not installed. I wouldn’t think that the chin spoiler would make a difference when the car isn’t moving. Opinions?

High flow thermostat – I just put a new water pump on. Will a high flow thermostat make a difference without a high flow water pump? One step further – I’ve tested it with (see original post) no thermostat. In light of that, could a high flow thermostat improve it?

Expansion tank cap – Since I have the aluminum expansion tank, should I buy the AC RC-26 cap, or will that make a difference?

:iagree:



Regardless, what's your actual timing at? Additionally, you're not doing your engine any favor by running that 160* thermostat.

A few points:

Just because the factory manual 40 years ago says that normal operating temperture is 210 degrees does not mean that is the best temperature for your engine to run. i am sure that 210 is "normal" for your BB, but if it was me I would want to lower it a bit for a number of reasons:

1. The factory running temperature was limited by how much GM wanted to spend to lower the temp (AKA aluminum radiator, high flow water pumps etc) and the technology available at the time.

2. Running 210-215 temps leaves little margin if the car begins to get hot for whatever reason.

3. There is no running efficiencies above 180-190 degrees.

4. High temps hurt performance above about 190 degrees.

5. High water temps really tax the oil- more on that later.

6. High water temps in the late 70's was all about emissiions compliance.

My 78 L-82 4 speed routinely ran 225-235 degrees with AC on and 90 degree ambient temp when new since GM had no other way to get the L-82 to pass emissions at that time. Quite frankly, it was ridiculous-the car was an oven!! GM even changed the 79 temp gauge to 225 at 12 O'Clock from 200 in the 78 due to customer questions about the operating temperature of the car-the needle of the gauge was 3/4's to the red zone, normally. Years of trial and error, resulted in my current configuratiion of Dewitts aluminum radiator and a Stewart Stage 2 aluminum water pump with a high flow thermostat resulting in a running temperure today on a 90-95 degree day of 180 degrees-GM mechanical L-82 fan and GM L-82 fan clutch. The car has never run better!

When the car ran 235-240 on really hot days, the oil temp was 250-260 which is very marginal! I have an 81/82 oil temp gauge where the clock use to be. If your car is an automatic with the trans fluid cooled by the radiator, running 210-215 degree water temp means that the trans fluid temp can never be less that 210-215 which again is very marginal on the fluid and will shorten the life of the tranny.

Although 210-215 is probably pretty normal for a BB, there are benefits to running lower temperatures if you want to go that route.

Hope this helps!

JB78L-82, Do you mean regardless of temperature?
36* @ 3000 rpm.
I'm not inclined to believe the 160* thermostat will have a negative effect on the engine because the temps climb to 180* (or more) just as fast as if I had a 180* thermostat in it. In cold weather, that may change, but for now it isn't a factor.

The DeWitts will be a nice effective upgrade and although the dam doesnt do anything at idle it will cool quicker as you move meaning once back at idle youll probably be running a lower temp and not fighting to bring it back down as hard.

Which renders the discussion about 'performance' irrelevant.

Not sure what you mean by "regardless of temperature". Yes, my engine has 36 degrees timing all in by 3,000 RPM.

jb78L-82 - Your original post: "Regardless, what's your actual timing at?" I was asking if you meant regardless of temperature.

There is some stuff that you can put in the Radiator that helps cool even more than normal Rad fluid. You can get it at Parts store.

TCT

That's incorrect.

That came from 69427-not me.

99% of new cars run at 210 degrees

All antifreeze/coolant already has exactly the same stuff it- adding more does nothing.

I bet your ignition advance is not correct. Give it more and see if the temps go down.

I have a stock rad, with stock fan and everything. I have a 180° thermostat and I really have to push it or get really hot weather to get it up there. Mostly stays around 170

jb78L-82 - My apologies for misquoting you. I made an attempt at disambiguation, and made matters worse.

Belgian - I have tried all possible combinations of timing within the range that the car will run and not detonate, and the temperature stays at 210.

Water Wetter - It was $18. If it helps, great. If not... it was $18.

One of the questions that I was hoping to get an answer to - the carburetor (original) has two small vacuum ports, both pointing toward the front of the car. Did the car come from the factory with the vacuum advance attached to the port on the driver’s side of the carburetor or on the passenger’s side of the carburetor?

Driver side...ported vacuum. Allows for leaner idle. Causes higher operating temperature.

Your engine will run cooler on manifold vacuum.

I put mine back on ported vacuum after re-curving the distributor and installing a more appropriate vacuum canister for my engine. I am just trying to make the car the same as it left the factory...at least in appearance to the un-trained eye.

another thing to check. I found out my pcv was playing havoc on carb mixture. See if that's the issue. You could be running leaner on some cyls because of it. It happens because some camshafts produce lower vacuum than what the PCV was designed for.

Thanks Faster Rat (and everyone else). I browsed Doc Rebuilds site and found a document that shows the factory routing of the relevant vacuum lines. Since the spark control solenoid has been removed from my car, the vacuum line runs directly from the port on the front/drivers side of the carburetor to the vacuum advance. My plan is to cap the port on the carburetor and tap the manifold vacuum, which should eliminate any further need to mess with vacuum. Afterward, I’ll check the timing and change it if necessary.

My 2001 Pontiac Grand Prix runs at 190 or less. Fans come on before the engine hits 210 on the gauge to bring the temp back down to 190. I would not equate modern engine temps to a 40 year old car.

Your problem is right here : "- The fan clutch seems to be working correctly. Even with the engine hot, I can turn the fan clutch by hand."
The best way to check for a defective fan Clutch is : get it good and warm 210 is great open the Hood then have Someone shut off the Engine while You observe the fan. It should stop turning almost immediatly after the Motor stops. At this temperature it should be locked up tight, if it keeps spinning replace the Fan Clutch.

Try a Hayden clutch fan ref:2799
Use a 180F thermostat (160F is too low and won't cure any cooling issue)
Check your radiator Plug (low pressure inside cooling circuit tend to running hot)


This is probably already done but:

Set your timing to have all in before 3000rpm.
Try to have max advance without knock, so il will determine your idle advance timing
for exemple:
34°@2800
HEI mechanical advance is 20° (20° is the norm but you need to be sure)
so you need to set idle timint at 14°

after this set your vaccum advance and plug it on Full vaccum port to help idle cooling


hope this help


Ps: My 350ci ZZ430 run 1st mark of temp gauge (approx 180F) all day long

The fan clutch doesn't "spin" when I shut the engine off at 210, but I can definitely turn it by hand. Ironically, it's the only part in the cooling system I haven't replaced.

:willy: I assume you have a good/calibrated IR heat probe, and have verified your temps.....a good thermocouple gauge like on my Fluke DVM works good also, but you have to heat sink it to the head for 100% accuracy.....I have both, and they agree on every test....so I"m cool with the IR gun I use.....

NOW, I have noted over the years that on thermostats of years past, they had different size openings, the 160 and 180 stats were larger diameter holes in the center, allowing more flow of course, when open that is, TODAY, and are all smaller openings like same as the 195f stats, so only the opening temp is affected, but overall flow is the same....

to get around that I drill 3-4 3/16 holes in the skirt of the stat, which is about as large as I can go without messing up the mounting or function.....this will make warm up a tad longer, and in really cold winters on the freeway I note that it runs about 150-160f but that's rather seldom driving for me....

:smash::yesnod:

oh, BTW, my aftermarket cheepy gauge reads 10f too high, as proven by above instrumentation......so I just mentally knock 10f off the readings....

I have an infrared thermometer that reads 10 degrees higher than the gauge when I point it at the water neck. "Calibrated" ... not really. "Accurate"... I would say pretty close. I'm intentionally leaving the 160 thermostat in place until I see some temps come down, but it will definitely come out at the appropriate time.

I also drilled holes in my thermostat, as well as tested it with a gutted thermostat and no thermostat. All 3 approaches resulted in 210+ on the gauge and 220 on the infrared thermometer.

So does it get cold enough in Orange Park to need the heat? : ]

That sounds like a correct reading. Water enters the block and then goes up the heads and out the water neck. It warms up all along the way. Water temp should be higher at the water neck than in the head (where the gauge sender is).

There's nothing wrong with your fan clutch. They never lock up solid, by design.

can I ask a question about the temp gauge? Sorry don't want to hijack the thread but it does kinda go with it, anyway, what does the mark between 100* and 200* represent on a 76? I was thinking tha tit was 150* but from reading through this thread I'm rethinking that.

The lower driver side port on many '70s quadrajets is for EGR, which comes on later than the ported vacuum for the distributor which is the lower passenger side. Full manifold vacuum is from either the tube coming out from the choke assy, or from the upper pass side port which feeds the choke pull-off. This latter port often has a tee in the hose which can be used as a source for ignition vacuum advance.

To be sure, apply a vacuum gauge to each source and read the vacuum. Changing from ported to full manifold vacuum will instantly raise the rpm at idle which will then require a partial closing of the throttle with the curb idle speed set screw... The end result is a more efficient idle and lower idle temperatures.

I recommend letting the car's temperature come up to that mark and checking the engine temperature with an infrared thermometer. That way, you'll know the temp no matter what they intended.

I've done that and my 180 t stat opens just a hair above the first mark so it has a good deal of ways before it gets to the 200 mark.

Marc,

I have been fighting a hot engine in mine for a while. My fan shroud was shot when I did my motor replacement so I didn't reinstall it. Consequently I am running warm, although it is encouraging to see here that the water neck temp should be higher than the head temp. My heads don't have a sender provision so I had to mount my sender in the thermostat housing. I am running a 180* thermostat and I generally run about 185-210 most of the time. Idling in traffic gets scary at times so I am going to try to install an auxiliary fan. I have another thread on here asking for some help getting the wiring diagram down, so if you are interested I can link you over there and I will post pics when everything is finally hooked up. I am going to try to use a 12" pusher initially just to give it a bit more help. Something to consider.

Update / recap - I've made great progress on getting the temps down in my LS-5 / 454 car. Even with the factory radiator (not aluminum), I'm rarely seeing 210 degrees anymore, even around town. This is what the improvement can be attributed to:

- Make sure you aren't losing any coolant. (I had pin holes in the radiator and expansion tank.)
- Drill two .250" holes in the skirt of your 180 degree thermostat.
- Run 93 octane fuel (in any engine with higher than a 9:1 compression ratio)
- Run 80/20 distilled water to antifreeze ratio and add a full bottle of Water Wetter
- Run vacuum advance from manifold, not from carburetor (this made a really, really big difference in the operating temperature). While you are at it, replace all the caps on your carb vacuum ports with new ones. (Costs less than $5)
- Set ignition timing to 36 degrees at 3000 rpm. I got my best results by setting the time to 36@3000, then making several very minor adjustments until the car to run smoothly.
- Make sure your lower (vacuum side) radiator hose has a coil in it so that it doesn't collapse under pressure.

*not running a high volume water pump
*not running a high flow thermostat

I have had a lot of cooling problems with my '72 small-block and everything described here has been part of the fix (aluminum rad, timing, vacuum, chin spoiler, electric fans, high-flow water pump, water wetter). The only thing that I changed that was not mentioned here (and may be helpful to you) was the lower rad hose. I put in the one with the spring to make sure it doesn't flatten out and reduce coolant flow.

You can find an example of the BB version here:

http://www.ecklerscorvette.com/corve...1969-1974.html

Good luck! :thumbs:

I'd say that these two adjustments were responsible for 99.9% of the cooler running at idle. The rest, especially higher octane gas, did little or nothing.

The higher octane fuel allowed me to set the ignition timing so that the engine ran cooler without detonation.

Did you actually experience detonation? Your '72 should run just fine on regular.

Absolutely. I experimented with 87 Octane, 89 Octane, and 93 Octane, and the result was exponentially better as the octane went up.