4 or 6

Timing is good as far as anyone can tell.


I will remove the restriction and see if there's any difference, although I won't be able to test the real world where I am now.


All those who say that 2 blades is good enough, have you pulled 7%+ grades in 100 degree heat starting out at 7,000 ft altitude? Crawling along below 15 mph. The Tulsa Oklahoma A's test shows that a 4 blade fan pulls 130% more air.
 
2speed said:
Clean block, actually the cleanest block you can have. Radiator was cleaned and repaired, original.


60/40 antifreeze solution. Engine pans are in place. Have a license plate because it's law.


Running a temperature gauge in the neck.


Have a thermostat with the thermostat knocked out, so a 1 inchish hole to slow the water down. Before knocking the thermostat out, car would overheat on hills easily.


Climbing hills at 7,000+ feet on 100 degree days is tough, to the point of pulling over and waiting.


50mph on 100 degree days is running between 185 and 190. Car is loaded pretty well. When it's 80 degrees out car will run 5-10 degrees cooler.


While this was stationary tests: https://www.tulsamodelafordclub.com/model-a-fan-air-flow/


4 blade is significantly more air. There is another article out there from years ago, but the scan is too small to read by Ed Rossig.


If you have a wind perpendicular to or behind the car, the air flow through the radiator might not be the "doesn't matter above 35mph" that you think it is.
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Why on earth would you want to slow down the water??? I have never seen a problem corrected by reducing the efficiency of one of the components.
 
2speed said:
Timing is good as far as anyone can tell.

All those who say that 2 blades is good enough, have you pulled 7%+ grades in 100 degree heat starting out at 7,000 ft altitude? Crawling along below 15 mph. The Tulsa Oklahoma A's test shows that a 4 blade fan pulls 130% more air.
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Where on earth does it get to 100° F at 7,000 ft. elevation? Flagstaff, AZ is at 6800 ft. and has never recorded 100° F.
 
I have the cast alloy two blade fans on all my A's, and have no overheating issues, even in Aussie summer heat. My thoughts are to look at the radiator flow. The tubes are easily blocked if you over grease the rear water pump bush/bearing.
 
Reading thru this thread l am in the camp that supports the idea that the fin-tube connection has become corroded creating a poor heat flow from the tube into the fin therefore the efficiency of the radiator is kaput. A new radiator will be the solution. IMHO
 
AzBob said:
Where on earth does it get to 100° F at 7,000 ft. elevation? Flagstaff, AZ is at 6800 ft. and has never recorded 100° F.
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Southern Utah. Zion was at 106 degrees. Capitol Reef, Mesa Verde is 9000ft. All of which were hovering around 90 degrees. Grand Canyon was 95 degrees and 7000 ft.


2025 Flagstaff Weather Extremes Highest temperature 92 °F July 9



Guess when I was there?


I'm not over heating running to get ice cream, or seeing the grandkids. I'm not overheating sitting at a traffic light.



I'm overheating pulling significant grades, at low speeds, for miles at a time.


Instead of saying something about 4 or 6 blade fans, in terms of fit, quality, and the simple fact that tests show it pulls more air....all I get is that it never happened to me.


A radiator replacement maybe something I can do in the future, but a $100 fan could solve the problem today.
 
I would get the 6-blade fan because performance is very similar to the 4-blade fan and there have been some incidents with 4-blade fans breaking. Since you’re doing a lot of touring, you probably want something trouble-free.
 
Thanks Katy for the link ! I haven’t found any good flow testing. The model A times test good only with the test in front of the radiator ! Why not the test behind the radiator in front of the motor ? Because the fans NOT being shrouded air comes off the sides of the fans and the air is disrupted ! The air in front of the radiator is what is cooling going through the radiator ! In mph the 2 bladed fan is better or equal !

On for the OP’s overheating, boiling over ? Temperature ? less than 15 mph up hill in second gear lugging the motor or in first gear screaming and pulling cooling air through the radiator . 60/40 antifreeze is good down to -60*F why do you need it at low ? Boil over protection at 230*F ? With a higher precentage of antifreeze it doesn’t cool as well, why not 100% antifreeze ?? Because you soon would cook your engine ! A 30-70 % or 40-60 may be a better choice since he doesn’t have time to change from one coolant to another coolant . Sorry for my rant ! My testing with water plus water wetter to 50-50 antifreeze showed me water cooled 30*F better . My A was running 195-200*F with a 50-50 antifreeze mix, I thought that was too high and switched to water with water wetter for anti rust and better cooling. Little know fact that the manufacture of antifreeze have too add anti rust chemicals to their products !

I finally bought a new radiator that cools to well and I am running 50-50 mix antifreeze to bring the operating temperature up to 170-180*F
 
I wish someone would Google 'Does Antifreeze need to be under pressure to work' and report back what the manufacturers say. Then, let's start a poll on how many have pressurized cooling systems in their Model-A.
 
BRENT in 10-uh-C said:
I wish someone would Google 'Does Antifreeze need to be under pressure to work' and report back what the manufacturers say. Then, let's start a poll on how many have pressurized cooling systems in their Model-A.
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If you do Google this you will get a misleading answer because in colloquial speech the word antifreeze is used interchangeably with the word coolant. What you’ll get is people talking about whether your car’s coolant system needs to be pressurized to work, and of course in modern cars the answer is yes. If you are talking about literal antifreeze, ethylene glycol, then no, it does not need to be pressurized to work, and the proof of this is that there is documentation of Ford dealers putting ethylene glycol antifreeze in Model As in 1929 and reporting that it worked great.
 
alexiskai said:
If you do Google this you will get a misleading answer because in colloquial speech the word antifreeze is used interchangeably with the word coolant. What you’ll get is people talking about whether your car’s coolant system needs to be pressurized to work, and of course in modern cars the answer is yes. If you are talking about literal antifreeze, ethylene glycol, then no, it does not need to be pressurized to work, and the proof of this is that there is documentation of Ford dealers putting ethylene glycol antifreeze in Model As in 1929 and reporting that it worked great.
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Yes Colin, however right now it is Summer, and the main topic in this thread is about a Model-A with an overheating issue -and not about preventing freeze cracking.

So yes, Antifreeze mixed with Water can prevent freeze cracking so we all should agree that it has its place for use in a Model-A ....however the suggestion from many, (-both here and on Social Media) is that using a mixture of Antifreeze is better at preventing overheating instead of straight Water. Why isn't this considered misinformation??
 
BRENT in 10-uh-C said:
the suggestion from many, (-both here and on Social Media) is that using a mixture of Antifreeze is better at preventing overheating instead of straight Water.
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OK if that is in fact the suggestion then that's certainly incorrect. I don't recall seeing that proposition in this thread, though.
 
[QUOTE using a mixture of Antifreeze is better at preventing overheating instead of straight Water.][/QUOTE]

That's only true in a pressurized system.
 
Sometimes, with old classics, the engine fan is replaced by an electric one. The fan is controlled with a temperature switch. Electric fans can be mounted on the outside or inside of the radiator. Small ones can be in conjunction with the normal engine driven fan and put on the inside down lower.
 
katy said:
[QUOTE using a mixture of Antifreeze is better at preventing overheating instead of straight Water.]
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That's only true in a pressurized system.[/QUOTE]

In one of my modern’s it was overheating, drained flushed, filled with water and cleaner, drained after a time, filled with water and water wetter and antirust, it ran soooo coooooled ( only 160*F ) that I put fresh antifreeze in and it then ran at a normal 194*F
 
[/QUOTE]In one of my modern’s it was overheating, drained flushed, filled with water and cleaner, drained after a time, filled with water and water wetter and antirust, it ran soooo coooooled ( only 160*F ) that I put fresh antifreeze in and it then ran at a normal 194*F[/QUOTE]

I would suspect the "water wetter" for the additional cooling.
 
Dan McEachern said:
Be aware that often with old original radiators, the fins don't make good contact with the tubes and can't transfer the heat. There is no fix for this other than a new radiator or core. Its a common problem with old radiators- just throwing that out there . Hopefully this is not the OP's problem, but.......
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Yup ! totally agree. That's what my issue was. I spent a lot of time screwin around and in the end the radiator wasn't radiating. Tube to fin contact is a must.
 
Too many varying and conflicting comments here to reply to, so I'm just going to state some easily verified facts. It is a fact that pure water is one of the highest liquid heat absorbers that exists. Ammonia is one that exceeds it. Believe it or not the milk you drink rates almost as high as water. The level of heat absorption of 50/50 Ethyl Glycol antifreeze is about 85% of that of water. In other words, straight water heat absorption is 117% of that of a 50/50 mix.

As far as pressure is concerned, the effect on pure water boiling points with increased pressure are in line with those of various apportionments of water and antifreeze:

-
571244


There is no where in North America (other than the Arctic perhaps) that should require more than 50/50 antifreeze and I don't think I've ever seen 60/40 for sale. 50/50 mix begins to freeze into slush around -35 degrees F but is not solid or harmful until somewhere in the low -40s.
 

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Randy in CA - Please help! The chart shows at 0 psi water boils at 212*, and 50/50 mix at 226*. How does this square with “straight water heat absorption is 117% of… 50/50 mix.” Does higher heat absorption not equate to a higher boiling point? Maybe the 50/50 mix is picking up less heat, not more? I’m missing some crucial point.
Thanks.
 
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