350 sbc heat soak

Dayzedandkonfuzed

G-Body Guru
Feb 9, 2010
943
93
Anglemont, BC
My Cutlass would creep up to 220 or better after shutting it down, not a big issue, just a symptom of no coolant flow. I did eventually wire my thermal fan switch to battery rather than key on, so it would cycle a few times after I shut it down. Did I have to? probably not, but it made me feel better.

I am also leaning toward an ignition issue as far as the no start when hot. Although not all that common for Gm HEI's, it sure sounds like an ICM getting a little too warm. And yes, every edelbrock carburetor ever built needs a phenolic spacer. They don't even like normal operating temperatures.
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
4,830
113
Upstate NY
I have ordered the spacer, its on the way and yes, my radiator set up is really good, i dont think its the issue, i am more concerned if my rear end can cause a lot of excess heat in which case ill swap it to lower gears asap which i need to do already.
You need to verify that the ignition timing isn't hurting you. Meaning your dizzy's mechanical or vac advance isn't stuck.

Get a thermostat back in it. Verify that the upper hose get's hard (pressure) after the thermostat opens. If it isn't then the system isn't developing pressure, and most .likely due to a minor rad leak or a bad cap. A budget heat gun is your friend here, as well as a timing light.
 
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64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
4,830
113
Upstate NY
Here is another good read for cooling system design basics for laymen. And its written by a LS swapper too so that will be double points for some of you.

http://billavista.com/tech/Articles/Cooling_Bible/index.html

Also not running a T stant delays warmup which increases engine wear. As I said betore 200 degrees is fine.
Read it. Some good stuff and some completely contradictory and incorrect info.

Need turbulent flow (p.s. that’s caused by the thermosta), and then says flow rate is not relevant.

A thermostat is needed, period. Or a restrictor of some some nature. The radiator transfers heat via a time factor - the coolant needs time to be cooled while in the radiator. If the coolant is only in the radiator for less than 50% of the time needed then it will be returned to the engine at delta t/2 temp.

Have the author of that article stop over to Cummins and see what they say about it. There is training that identifies the hole in the ‘no thermostat is ok’ theory.
 
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Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
3,241
113
Galaxy far far away
Read it. Some good stuff and some completely contradictory and incorrect info.

Need turbulent flow (p.s. that’s caused by the thermosta), and then says flow rate is not relevant.

A thermostat is needed, period. Or a restrictor of some some nature. The radiator transfers heat via a time factor - the coolant needs time to be cooled while in the radiator. If the coolant is only in the radiator for less than 50% of the time needed then it will be returned to the engine at delta t/2 temp.

Have the author of that article stop over to Cummins and see what they say about it. There is training that identifies the hole in the ‘no thermostat is ok’ theory.

For no T stants causing overheating,, its one of three things, pump cavitation at the water pump, lack of restriction causing the coolant to bypass the temp sender, or causing greater pressure at thd cap and lifting if if its located on the high pressure side of the rad. A possible 4th issue may be due to the engine design. Water will seek the path of least resistance. So in poorly designed cooling systems, a restrictor might be needed to prevent waterflow from bypassing parts of the system like intake manifolds and heater cores. Again its not to slow down flow but to force the water to better scrub surfaces, ie laminar flow vs turbulant flow. You don't want laminar in the cooling system.

Again, coolant needing time in the radiator to shed heat is a myth. In order to spend more time in the rad to cool it also will spend more time in the block overheating. If you slow down coolant to decrease the rad's outflow tank temp, you will also increase the temp in the inflow tank which counteracts the benefits of the lower temps at the outflow tank. In other words, to make the cold side colder with lower flow you also make the hot side hotter which isn't good. The block could be melting down while the rad outlet is icy cold. This is because for any given heat load and coolant flos that are constant, the temp drop through the rad is constant. Temperature is not really a direct measure of how much heat energy a item has absorbed or exchanged. Different materials require different amounts of thermal energy before their temps rise or falls, this is called specific heat capacity.

Think of heat transfer as a domino effect. In still water the outer molecules shed heat to the outside, then absorb heat from the next water molecules in the interior which are shed to the outside, over and over like dominos until equal temps are reached. The rate that this happens depends of the temp diff between the water and the outside environment. However, if you circulate the water the heat transfers faster due to having to deal less with the domino effect as you are stirring and scraping more water molcules against the exterior releasing more heat faster. Moreover, there are a couple of issues with increased flow, diminishing returns, stress, and robbing HP. There is no way to defeat Q = m × c × Delta T, it seems it should be made a sticky for the cooling section to dispell cooling myths.
 

John Canon

Not-quite-so-new-guy
Apr 19, 2022
48
18
Vancouver Canada
This is ...

Too Much.jpg
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
4,830
113
Upstate NY
Clone TIE Pilot

So with your theory you really don’t need a radiator?

I know the answer to that. It takes time for the rad to cool the coolant.
Do you disagree with this? I’m asking because your posts indicate that cooling happens by elf’s and magic.

I agree that the coolant can’t spend too much time in the engine. But a well engineered system allows for the coolant to be in the engine and radiator to maintain a consistent temp. It can’t be in either for too long or too short of a time. The water pump flow/engine speed and thermostat control that - correct?
 
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abbey castro

G-Body Guru
Oct 31, 2015
668
93
Harker Hts TX
After reading TIE Pilot's PHD dissertation I ask the following:
Why have OEMs, since the creation of the wheel, installed the following:
1. Radiators w/an inlet and outlet hoses
2. A water pump with associated hardware/parts to move coolant within components
3. A Radiator Cap rated for different lbs of pressure
4. A thermostat
5. A fan to move air through the radiator
6. A shroud to channel air through the radiator
7. Either an Idiot Light or a Gauge to indicate temperature
8. An aperture in the front to let air flow through (Ford did the radical thing with the Taurus by eliminating the grill opening and ducting air flow from the bottom of the front facia. Turbo Buicks air box underneath, chin spoilers

If this is all for naught, the corporate bean counter would have said "NO WAY JOSE YOUR GONNA PUT THAT STUFF ON A CAR"
 
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John Canon

Not-quite-so-new-guy
Apr 19, 2022
48
18
Vancouver Canada
The engine's cooling system is physically a closed system, but thermodynamically it is far from a closed system. The simple equation leaves out so many factors. For example: draft air over the engine, water jacket hotter and cooler areas, and flow direction through the engine block.

Plus there is one factor that is continually being ignored: the thermostat, even when fully open, does not pass all water flow into the radiator. There is always a circulating flow around the cylinders, etc. The thermostat just passes some, but not all, hot water through the radiator.
 
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