4 blade vs. 2 blade alum. fan

[1965 Mustang]

Broken fan blades must tend to do more damage on model A's. I had blades break and fly off of my 1949 Plymouth some years ago and it did no damage at all. (other than having to buy another fan) Maybe I was just lucky.

[DougVieyra]

On my '28 Phaeton, I use an original 'Ford-Made' two blade fan, with an inch cut off of each blade. Supposedly this helps reduce some of the stress (weight, centrifugal force, etc.) on the water pump shaft; the reduced length of the over-all fan blade length has not reduced the effectiveness of the cooling. I have been using this original fan for the last 45 years. I suppose it is time to take it off and examine it again for cracks*. If a replacement is necessary, I will use a newly-made aluminum fan blade sold by the Parts Houses. Today's NEW aluminum fans should relieve all of those possible problems.

*It is also of critical importance to thoroughly check (with magnifier) for any cracks or other imperfection on an original Ford-Made two-blade fan. Metal fatigue is the number one culprit in fan failure.

On another note, my '28 Phaeton has both of it's Engine Pans installed, as per factory. This too is supposed to help with the fans cooling of the engine compartment. Also, while Ford did drop the idea in 1929 onward, my '28 also has the factory radiator fan shroud. All of this, I am sure, does some help in keeping the engine cool, with just a two-blade fan.

That being said, on my '31 Dlx Coupe, I have a new six-blade plastic fan and am quite pleased with it's engineering and performance. And just for the historic connection, I have also installed an after-market Fan Shroud on the radiator, as was done on the '28 A's, even though I am fully aware that the conventional wisdom is that they are not really needed. And too, I do have the engine pans installed, as per factory / service recommendations.

[updraught]

Chopping a bit of the fan, I think, changes where the bad harmonics gang up due to the slop in the front bearing.

[katy]

The 2 blade fan on our '31 CCPU is one piece, no rivets. It's not aluminum, it's either steel or cast iron, (a magnet sticks to it) not sure which as it is painted. It kinda looks like the fan and the pulley are 2 separate pieces.

[Kahuna]

Doug
Who makes/sells the fan shroud you mentioned?
Thanks
Jim

[DougVieyra]

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Jim (Kahuna)- I bought my '30-'31 Fan Shroud several years ago, I don't remember from whom.

However, a quick look at my catalogs of Model A "Parts Houses", shows that Snyder's Antique Auto Parts has them listed on Page 134 of their 2015 catalog. I also found the '30-'31 (and '28-'29) Fan Shrouds on their website: www.SnydersAntiqueAuto.com (their description below):

Model A Fan Shroud
"Originally these were only supplied on the early 28's. Very helpful in optimizing the cooling efficiency of your radiator. Attaches to the back of the radiator and includes mounting hardware. Black plastic construction. Makes your A run cooler. Dimensions: 1928-29, 19-3/4" High, 18-5/8" across top, 18-7/8" across bottom. 1930-31 22-3/8" high, 18" across top and bottom. Hole opening is 16-1/4" for both. U.S.A."
-1930-31: A-8050-301 $68.95 / ea.
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Jim, please note that these (both '28-'29 AND '30-'31) FAN SHROUDS are made of PLASTIC not steel as were the original shrouds of 1928.
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If Snyder's does not have them, try MAC'S, who have them listed on page 85 of their "Late 2014" catalog, part # 28-24568-2: $83.50. However, their current website lists them at $94.

[Capt Quahog]

This 31' Ford I've got came with a 4-blade fan. To long ago recollection, every other Model "A" Ford owned had a TWO-BLADE and everything seemed to hum along nicely. That present 4-blade fan makes too much wind and sounds like a prop of a DC-3 on warm-up. How much work would it be to swap out the 4-blade and install a TWO-BLADE as Henry Ford intended?

[BILL WILLIAMSON]

Dog here,
One IDIOT tole Dad thet if you FLIPPED a 4 blade fan, it wuld BLOW, instead of SUCK! Dad sed the guy needed a BRAIN overhaul
Youse Guys are NICE on this THREAD, on that uther one about fans, them guys make FUN of Vermins' 6 blade, plastic fan & I CAN'T tipe Dads' reply here ur I'll be in DEEP POO-POO
Buster T.

[Art Bjornestad]

I lost a blade from a 59a engine in a 46 ford. Luck was on my side as the blade went out the bottom of the engine/radiator space, cut a lower hose open.
The fan was a standard looking fan but I had never looked it over for cracks.

[DougVieyra]

It sounds like the two-blade ALUMINUM fan gets the most votes. Are there more than one manufacturer of the 2-blade Aluminum fan ? Does anyone know who (Parts Dealer) makes them ? If there are more than one manufacturer / source, which is the better ?

At the moment I am still quite happy with my original 87 year old original steel Ford-made fan. BUT after all these many years of service and age, this thread has made me nervous.

Knowing that often times there are a number of reproduction items that have a 'run' made and then the source dries up, I thought I would purchase the best aluminum fan I can get, NOW, and store it up for later use - if needed.

[Tom Wesenberg]

I think only Snyder's make them. That would be my first choice for a replacement if I change out my original 2 blade fan.

Speaking of putting the fan on backwards, shortly after I started working at the junk yard, I told the boss that someone put the loader fan on backwards. It took me quite a while to finally convince him that it won't push much air when it's backwards. Yes, the loader pushes the air forward, rather than drawing it towards the engine, and due to the curvature of the blades, it doesn't work well when it's flipped over.

[old31]

On the article that Tincup provided. Although difficult as it is to read it does show that the 4 blade definitely reduced temps over the 2 blade for both radiator temps and water temps by a large margin.

Based on the article my vote is for a 4 blade. No, it doesn't look as cool as a 2 blade.

[Brianfrench65]

So.....Mikes has a 4 blade fan special....

[Utopia Texas]

Call me crazy, but 32 years ago I took the four bladed fan from my 1931 late Slant Windshield 4 door sedan and welded the rivit heads to the blades, welded a bead where the blades Chris crossed and then welded a circular bead between the blades and the pulley. In effect this makes the fan all one piece. After reading all the comments above I now wonder why it has worked so long and on so many long tours. I am not a professional welder so some one clue me in if this was a stupid idea and I should switch to a different fan!

[BILL WILLIAMSON]

I demonstrate the SAFETY of my 6 blade PLASTIC fan, by putting my elbow to the back side of the blades. It just goes, "BRRRP"!
Bill Brave

[johnbuckley]

Originally Posted by Benson

....Here is a summary of the Model A Times fan tests:

http://www.tulsamodelafordclub.com/m...-fan-air-flow/...

I appreciate that they state the results are not scientific but could someone clarify these results for me please. The fan air flow MPH been measured with the car stationary. Thus for example in the 1000rpm table with 2 blader and the car going at 25 mph does the author believe the air is going through the rad at 25 +18 =43mph??? Or does he believe the fan is restricting the apparent wind of 25 mph because the fan is only inducing a speed of 18mph and thus is likely to be interfering with the total airspeed through the rad.

[MikeK]

Originally Posted by Utopia Texas

Call me crazy, but 32 years ago I took the four bladed fan from my 1931 late Slant Windshield 4 door sedan and welded the rivit heads to the blades, welded a bead where the blades Chris crossed and then welded a circular bead between the blades and the pulley. In effect this makes the fan all one piece. After reading all the comments above I now wonder why it has worked so long and on so many long tours. I am not a professional welder so some one clue me in if this was a stupid idea and I should switch to a different fan!

What you did created detrimental modifications in the grain structure of the rolled sheet used to produce the two overlapping blades. The welding added stress risers in the absolute wrong places. You now have a DANGEROUS fan.
Welding the four overlap joints of the two blades- two in front, two in the back, has made the fan far more prone to sudden blade loss than the riveted construction. You have concentrated the flexing directly across your weld beads. The grain structure in the steel sheet metal the blades are made from is refined, compressed, and stretched directionally during the rolling process. Essentially a type of forging. Your weld bead destroyed that. It annealed the metal and left a soft line with much less spring than the rest of the blade.

The fact that you now have many years of accumulated stress from dynamic flex on that fan makes it a real time bomb.

Didn't you post this under a different screen name 5 years & 11 months ago? My response was the same back then.

[Mitch//pa]

Originally Posted by Utopia Texas

Call me crazy, but 32 years ago I took the four bladed fan from my 1931 late Slant Windshield 4 door sedan and welded the rivit heads to the blades, welded a bead where the blades Chris crossed and then welded a circular bead between the blades and the pulley. In effect this makes the fan all one piece. After reading all the comments above I now wonder why it has worked so long and on so many long tours. I am not a professional welder so some one clue me in if this was a stupid idea and I should switch to a different fan!

Originally Posted by MikeK

What you did created detrimental modifications in the grain structure of the rolled sheet used to produce the two overlapping blades. The welding added stress risers in the absolute wrong places. You now have a DANGEROUS fan.
Welding the four overlap joints of the two blades- two in front, two in the back, has made the fan far more prone to sudden blade loss than the riveted construction. You have concentrated the flexing directly across your weld beads. The grain structure in the steel sheet metal the blades are made from is refined, compressed, and stretched directionally during the rolling process. Essentially a type of forging. Your weld bead destroyed that. It annealed the metal and left a soft line with much less spring than the rest of the blade.

The fact that you now have many years of accumulated stress from dynamic flex on that fan makes it a real time bomb.

Didn't you post this under a different screen name 5 years & 11 months ago? My response was the same back then.

Mike K gave you a scientific reason to your question of was it a stupid idea. My real world answer would be( if God forbid a personal injury was to occur)when the ER medical staff asks what happened (as long as you can still talk) to you or someone helping you under the hood, just tell them you knew about the dangers that's why you welded it but were to cheap to buy a 65.00 replacement fan. Just walking in the ER door will cost more than that, then you have to figure in any surgeries, rehab, loss of wages, etc...
Another scenario, someone inherits or purchases your car but little do they know it's actually a time bomb, then the unsuspecting gets injured.
I hope this help answer your question...

P.s. Just curious how did the fan balance out when you were done ?

[1929]

I have a two blade, temperature fluctuates from 160-170 depending on outside temperature.

[Utopia Texas]

Originally Posted by MikeK

What you did created detrimental modifications in the grain structure of the rolled sheet used to produce the two overlapping blades. The welding added stress risers in the absolute wrong places. You now have a DANGEROUS fan.
Welding the four overlap joints of the two blades- two in front, two in the back, has made the fan far more prone to sudden blade loss than the riveted construction. You have concentrated the flexing directly across your weld beads. The grain structure in the steel sheet metal the blades are made from is refined, compressed, and stretched directionally during the rolling process. Essentially a type of forging. Your weld bead destroyed that. It annealed the metal and left a soft line with much less spring than the rest of the blade.

The fact that you now have many years of accumulated stress from dynamic flex on that fan makes it a real time bomb.

Didn't you post this under a different screen name 5 years & 11 months ago? My response was the same back then.

Thanks for the response. Don't know if it was me who posted back then. In that period I was working over seas for a extended period of time and on returning to the US had a hospital stay for quite a while and was not on the Internet. I will look into another fan today.