350 sbc heat soak

John Canon

Apprentice
Apr 19, 2022
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Slowing coolant flow thru the radiator allows the transfer of heat in the coolant to the radiator tubes therefore the cooling fins cooled by the passing air, thus lowers coolant temp. That is a fact Jack! The restriction of the t-stat doesn't increase pressure the radiator cap does. That is a fact Jack!
Hey-y-y-Abbey!
You got those facts right! Also, the only time increased flow rate would increase heat transfer is if the radiator was so efficient that delta-T was extremely high. Then the radiator could handle the extra water and pull down the temp.
 
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Clone TIE Pilot

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Aug 14, 2011
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Slowing coolant flow thru the radiator allows the transfer of heat in the coolant to the radiator tubes therefore the cooling fins cooled by the passing air, thus lowers coolant temp. That is a fact Jack! The restriction of the t-stat doesn't increase pressure the radiator cap does. That is a fact Jack!
The equation for heat transfer Q = M × C × Delta T says Jack is wrong. Jack needs to retake High school science. Heat transfer rate is nearly proportional to mass flow rate.

Q= heat transfer rate

M = mass flow rate

C = constant (specific heat capacity)

Delta T = fluid temp out - fluid temp in.

As you can see, increasing mass flow rate always increases heat transfer.

Yes a t stant increases pressure inside the block, aka the high side and induces turbulance which increases heat transfer. For most cars the radiator cap is located on the low side of the cooling system.

https://www.google.com/search?q=hea...Q&biw=1024&bih=600&dpr=1#imgrc=4knMlvn0hOpSwM
 
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64nailhead

Goat Herder
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Dec 1, 2014
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Fine line between the coolant moving too fast thorough the radiator and not fast enough. If the radiator is efficient then it should be a minimum of a 30 degree difference between what's going in vs. out. If it's less than that, then most engines will not cool.
 

melloelky

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Oct 22, 2017
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Limiting the amount of coolant flow leaving the engine lets you control the amount of heat absorbed by the coolant itself there fore its length of stay in the radiator allows it to change the temp of the coolant.without a restriction(be it an actual t-stat or a restrictor plate)it has less chance of getting the treatment it needs In its time In the radiator.
 
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Clone TIE Pilot

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Aug 14, 2011
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Limiting the amount of coolant flow leaving the engine lets you control the amount of heat absorbed by the coolant itself there fore its length of stay in the radiator allows it to change the temp of the coolant.without a restriction(be it an actual t-stat or a restrictor plate)it has less chance of getting the treatment it needs In its time In the radiator.
The formula I posted above says that is false.


If you can move liquid coolant too fast, then that would also hold true for air moving through the radiator. Especially since gas has a harder time absorbing heat than liquids. So how come a cooling system always works better with increased airflow rather than slower airflow to give the air more time to absorb more heat out of the radiator?

Q=M×C×Delta T doesn't lie.


A restrictor in the outflow increases coolant pressure and induces turbulance ( increased speed) inside the block with is what increases cooling performance. ie the coolant spins around in the block passageways faster. Turbulance also increases heat transfer rate. If you increase the time coolant spends in the block it will boil in the hot spots and create steam pockets which will further insulate heat transfer making the engine even hotter. In fact still water is a great heat insulator, while flowing and turbulant water is a good conductor. The faster and more turbulant the faster it conducts heat.


Coolant needing extra time to sit is a old wives tale. I don't mean to give anybody here a hard time here, just trying to explain the true science and dispell hotrodding myths and this is one of the big myths.
 
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melloelky

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Be that as it may that"wive's tale" has always serve me well As I'm sure your math and algorithm has you.
 
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64nailhead

Goat Herder
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Dec 1, 2014
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The formula I posted above says that is false.


If you can move liquid coolant too fast, then that would also hold true for air moving through the radiator. Especially since gas has a harder time absorbing heat than liquids. So how come a cooling system always works better with increased airflow rather than slower airflow to give the air more time to absorb more heat out of the radiator?

Q=M×C×Delta T doesn't lie.


A restrictor in the outflow increases coolant pressure and induces turbulance ( increased speed) inside the block with is what increases cooling performance. ie the coolant spins around in the block passageways faster. Turbulance also increases heat transfer rate. If you increase the time coolant spends in the block it will boil in the hot spots and create steam pockets which will further insulate heat transfer making the engine even hotter. In fact still water is a great heat insulator, while flowing and turbulant water is a good conductor. The faster and more turbulant the faster it conducts heat.


Coolant needing extra time to sit is a old wives tale. I don't mean to give anybody here a hard time here, just trying to explain the true science and dispell hotrodding myths and this is one of the big myths.
Because one is a heat source and one is not. The engine can build and maintain heat. The ambient air flow is as close to having an infinite amount of energy to give away as there is for this example. If you were recirculating the air that has already cooled the radiator once, then your theory applies. But that's not the case.

I don't want to be argumentative, but your upside down here. The same principle applies for windchill. If the ambient air temp is 20 degrees and you have a jug of coolant on top of your car and you're traveling 60 mph the temp of the coolant in the jug will be a consistent 20 regardless of air flow because it's not a heat source and has nothing to gain or lose as long as it's at ambient temp. But if you put a heater in that jug and conduct the same test, then the jug will be cooler than the heater can heat it to because the ambient air is stealing it's energy.
 
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Built6spdMCSS

Royal Smart Person
Jun 15, 2012
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Florida Beach
Holy Jesus how did I miss this clusterfk....

Use time delay relays on your fans so they run for a couple minutes after you turn the engine off.

Tell me what that will do besides just cool the coolant in the Radiator and drain the battery..

I'm going to do my best to apply what I know of thermodynamics, physics, and common sense to un-potato this mess. Sheesh..

Hi, im Jaden and own a 82 Monte Carlo.

...but after turning off the car and letting it sit for more then a minute the temp rises pretty quickly to around 230~ while the car is off. When you go to fire up the car after letting it sit for a few minutes it cranks for about 15 seconds, maybe more, and once it finally starts it dumps raw fuel causing white smoke and runs flooded for about a minute or two until it clears up and goes back to normal.
Hi Jaden.
My question on this is how are you seeing this quick of a temp rise? Turning the key on and seeing the temp gauge spiked that high within a minute? If it's dumping that much gas before firing there is an ignition issue so it may be a bad coil or ICM. You have the gas, you lack the spark.
It has a Cold Case large 2 row radiator with dual electric 12" fans, stock water pump, and no thermostat currently. I have been dailying this car for weeks and am sick of this issue and the car running hot in general. Today while driving the temperature reached up to 200F which is strange because it doesnt even get above 190 while driving at all.
That is not hot, at all. You get into the 215 range then worry.
My dad has owned multiple gbodys and classics in general and we are stumped on this issue. Any and all help is appreciated, i will answer any questions in hopes of curing this heat soak/overheating!
Heat soak and over heating are two very different things. If the car runs at 200 at most, it's not over heating.

Parked sitting still with no air moving through the engine bay, hottest part is anything exhaust so that heat will dissipate all over the engine bay until it all cools off. That is heat soak.
Also, the car has had the rear end swapped from its stock low 2.41 ratio gears to what I thought was 3.73 gears with a posi but the car tops out at 50-55, im thinking the rear end may be closer to 4.10 gears or even 4.56s, will gears this high cause overheating due to higher rpm from the gears? Edit: I forgot to mention that you can hear the gas in the carburetor boiling away and after a little bit of time the fuel filter is completely empty. I have yet to see if the carburetor spacer affects this.
Higher RPM will generate more heat, yes. That much heat in the engine bay seems to be a lot and you are getting vapor lock if it's boiling gas off in the lines. Others can chime in here to help remedy that with some tricks, my stuff is all EFI.

Just trying to help with the above, the Radiator is not the issue here...
 
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64nailhead

Goat Herder
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Dec 1, 2014
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Also are you running a phenolic spacer under the carb?

Holy Jesus how did I miss this clusterfk....
Asleep at the wheel I'd say haha
Others can chime in here to help remedy that with some tricks, my stuff is all EFI.
565bbchevy answered this already, like post 3 or 4. He needs a phenolic spacer much more than a fan or radiator imo. And he ought to confirm proper timing and spark as well.

I referenced fan selection because the conversation turned to fans.

And you're spot on, 200 isn't too hot.
 
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