Running cooler - does this make sense?

[ct1932ford]

My 21 stud in my roadster runs very nice and cool. Temps will go up a bit when running higher rpms on the highway but never overheats. I always run thermostats.

[woodiewagon46]

In about 10 years the Ford Flathead engine will be 100 years old. One hundred years and we are still trying to get it to run cool.

[1931 flamingo]

Unless the radiator is up to snuff it's going to run hot..................JMO
Paul in CT Mine drops 30* from top to bottom, no stats.
Paul in CT

[Bored&Stroked]

When I was first started building racing flatheads (was 15 years old), quite a few old timers said to "cut off every other water pump vane, drill 1/4" holes in the rest and put washers with 1/2" holes in them in place of thermostats - you need to slow the water down to take the heat out of the engine".

I think it was nothing more than a HotRod misconception that was repeated over and over again. As mentioned earlier, I think the real issue was vertically mounted radiator cores/tanks that would overflow due to the amount of velocity/pressure a pump was pushing into the upper tanks. You pushed the water out at race RPMs, then the engine ran hot. In summary - I think these old tales are just that - they were trying to solve one problem (and did) and folks extrapolated the results in a manner that is technically incorrect - but repeated all the same. (Lots of flathead stories are like that. )

Also, I see no reason to not run a pressurized system with a recovery tank - especially if purchasing a new radiator.

Here is a blurb from Stewart Water Pumps: (They make some of the best high-performance and race pumps for modern race engines) . . . enjoy! Dip that hand into that popcorn, get butter all over it and sit back and let the fur fly!

From Stewart Water Pumps:

A common misconception is that if coolant flows too quickly through the system, that it will not have time to cool properly. However the cooling system is a closed loop, so if you are keeping the coolant in the radiator longer to allow it to cool, you are also allowing it to stay in the engine longer, which increases coolant temperatures. Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures.

Years ago, cars used low pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would overcome the radiator cap's rating and force coolant out, resulting in an overheated engine. Many enthusiasts mistakenly believed that these situations were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool. Using restrictors or slowing water pump speed prevented the coolant from being forced out, and allowed the engine to run cooler. However, cars built in the past thirty years have used cross flow radiators that position the radiator cap on the low pressure (suction) side of the system. This type of system does not subject the radiator cap to pressure from the water pump, so it benefits from maximizing coolant flow, not restricting it.

[Steve/IL]

Please reread Post #10, particularly the last 3 lines. It is important to have some pressure in the system to prevent cavitation erosion of the cast iron block and especially aluminum heads. Thermostats are one way to increase system pressure and, of course, to control a minimum temperature for efficient combustion/fuel consumption.
Another way to increase system pressure is to use a low pressure radiator cap, even for a stock radiator, which should to able to handle 4 to 7 psi. A pressure cap also minimizes the amount of coolant lost through the overflow.
What is too hot! To some, anything over 160 degrees F is too hot! 180 to 190 F, even 200 F, in a flathead is better for efficient combustion. Remember late model engines typically run 210 or more.

[FlatheadTed]

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Some good points you could take , I agree with Flamingo You see in the book there were various radiators offed ,,swap meets can yield some good radiators ,Cores up to 39 are basically the same size ,you can pick up two pipe radiates for a song I add two more pipes remove the top tank and clean them ,what removes heat is air more air more cooling ,or more tubes more cooling ,A high flow pump gets more water through the tubes or helps a otherwise semi blocked radiator ,I have experimented with the early 21 stud pumps its surprising how much they flow ,a shroud or a 6 blade fan can give 15% or so more cooling ,If you were rebuilding a Radiator I would add another row of tubes ,

[FlatheadTed]

On a early motor the pumps are after the motor so creates a low pressure zone ,I agree with the washer impeller deal was a stock car fix, two of my cars run identical LB blocks one i have thermostats in the other not ,the reason it was running to cool ,I run a Toyota thermostat welded to a SS tube with a 1/8 hole drilled in it ,I did run a pressurized system mainly to get a small tank radiator to work ,(experimental ) at one stage .I did a wedding for someone when my 34 was first built it dumped dirty water over the wind screen (thought it boiled big clean up ) I experimented with a washer etc ,then I finally put a decent seal on the cap ,problem solved .I was at a car show and ran the 34 up to show how the fan and shroud sucked ,there was a guy standing to close to the front it took two of us to pull him of the Grill because of the suction .

[MGG]

Whenever these types of issues come up, I always revert to the following: Does anyone really think that Henry would have wasted money on extra impeller fins and oversize hoses that were not necessary? My father maintained a large fleet of Ford V-8 construction trucks in the 30's thru 50's and he always scoffed at non-factory modifications.

[Karl]

Originally Posted by MGG

Whenever these types of issues come up, I always revert to the following: Does anyone really think that Henry would have wasted money on extra impeller fins and oversize hoses that were not necessary? My father maintained a large fleet of Ford V-8 construction trucks in the 30's thru 50's and he always scoffed at non-factory modifications.

Agree 100% !

[aussie merc]

as i say henry was the quintessential tight wad if it wasn't needed you didn't get it yet he fitted thermostats and if you take a look at one its little more than a washer with a valve that's temp controlled the water pumps had 6 fins and moved considerable coolant so the so called modern pumps are more efficient in practice as the curved blades reduce cavitation modern thermostats still work the same when in reality all we basically need to do is fit a shroud which increases the efficiency of the fan and look at the radiator design ie number of tubes, area of tubes, surface area of fins and total coolant capacity of radiator ; the larger capacity actually slows the flow thru the radiator thus increasing heat transfer out of the coolant [production is always a compromise between cost and best practice] so there can be improvements

[Mart]

I have an aftermarket rad in my 32 with the filler under the right hand hood top. I ran it with no thermostats and a flat cap blanking cap on the rad with no pressure. It ran cold and hot and when ran with high revs for an extended period it dumped all it's coolant and eventually overheated.
I fitted thermostats and a 4lb cap.
It now runs at a decent temperature and does not throw water out.
I have some video footage that will get edited up some day.
My conclusion is that the stats calm the water flow down. Without the stats and just a flat blanking cap there is too much water rushing around and too much finds it's way out of the overflow. In my mind I can imagine gallons of water rushing up the pipes to the top tank and generating a pressure in the tank while it squeezes itself down the radiator tubes. That back pressure forces water out of the overflow because it is open to the tank with just a blanking cap on.
So if your radiator is a replacement type that can take a pressurised cap, use one and run stats too.
Every modern car runs a stat and a pressurised system. Millions of motorists worldwide can't be wrong.

Mart.

[flatjack9]

Going back to my engineering days, any fluid dynamics text book will say that heat rejection is a direct function of flow rate. More flow equals more heat rejection.

[tubman]

After many years of watching this, I have found that "flatjack9" is almost always right.

[alanwoodieman]

flathead jack--same as high flow pumps from Skip, but 50/50 mixture and a couple bottles of water wetter as per skip and gm