Fan question

L

LarryinWA

Senior Member
Maybe a dumb question but does a 4 blade fan cool better than a 2 blade? I would think so since it is moving more air? I am replacing a 45 year old water pump with 4 blade fan and am thinking of putting on a new 2 blade aluminum one since one of you suggested that. This is not a show car.
 
There was a study a while back that indicated the 2 blade moved more air than a 4 blade or the plastic six blade, if I recall correctly.
Paul in CT
 
No. The four blade fan does not move more air and is much more prone to breakage than the aftermarket two-blade fans.

Also, they don't look right on these cars. Not as bad as the plastic crap I see on some rigs, but just not right.
 
LarryinWA said:
Maybe a dumb question but does a 4 blade fan cool better than a 2 blade? I would think so since it is moving more air? I am replacing a 45 year old water pump with 4 blade fan and am thinking of putting on a new 2 blade aluminum one since one of you suggested that. This is not a show car.
Click to expand...

Actually this not the case.

The original Model A two blade fan was made to be 'aerodynamic.' It has the curves in the right spots to "guide" the air through it in most efficient manner.

The four blade fan was not made so aerodynamic - and the thought has been since and confirmed by testing that the blades are actually getting in their own airstream.

And the truth be known - once the vehicle is above say 20 mph, the fan, any fan, actually impedes airflow through the radiator.

Ford did put 4 blade fans on the later trucks - alongside the thicker radiators. Partly in error since they didn't do a lot of testing - but also because speeds on the roads were not to our present level - the fans might be mostly used below that threshold to where they are advantage?

The riveted 4 blade fans HAVE had some instances of the rivets becoming loose. I have one of these on the Gordon-Smith compressor in my avatar and intend to check this.

I also have a couple of the two blade fans that are made similarly - but these blades bolt to the turned steel hub - so shouldn't be a problem this way.

I think for my driver, I will be getting a new aluminum fan. There are few bad reports on these except some early production having the taper mount made incorrectly - but this has been solved on what is available now.

Joe K
 
The original two blade and the repro aluminum fans have more pitch than the old model 46 four blade truck fans. The aluminum repro two blade fan moves more air and is more safe. I agree with Joe K.
 
Joe,

Minor correction, the four blade fan was used on all 4 cylinder vehicles (trucks and passenger cars) from 1933 to 1934. It was also the replacement fan Ford dealers installed on all 1928 through 1934 vehicles according to the Green Bible.

Charlie Stephens.
Joe K said:
Actually this not the case.

The original Model A two blade fan was made to be 'aerodynamic.' It has the curves in the right spots to "guide" the air through it in most efficient manner.

The four blade fan was not made so aerodynamic - and the thought has been since and confirmed by testing that the blades are actually getting in their own airstream.

And the truth be known - once the vehicle is above say 20 mph, the fan, any fan, actually impedes airflow through the radiator.

Ford did put 4 blade fans on the later trucks - alongside the thicker radiators. Partly in error since they didn't do a lot of testing - but also because speeds on the roads were not to our present level - the fans might be mostly used below that threshold to where they are advantage?

The riveted 4 blade fans HAVE had some instances of the rivets becoming loose. I have one of these on the Gordon-Smith compressor in my avatar and intend to check this.

I also have a couple of the two blade fans that are made similarly - but these blades bolt to the turned steel hub - so shouldn't be a problem this way.

I think for my driver, I will be getting a new aluminum fan. There are few bad reports on these except some early production having the taper mount made incorrectly - but this has been solved on what is available now.

Joe K
Click to expand...
 
Last summer we had a rash of 4-blade fan failures. 2 of them broke at the joint and spun the blade off as 28A described. The other 2, the rivets that hold the 4 blades to the hub failed. One was caught before it got into the radiator, unfortunately mine wasn't. Both of the fans with rivet failures were subsequently repaired by replacing the rivets with aircraft grade bolts and lock nuts, and have been working just fine since then.
 
The 2 blade aluminum fan is well made and works extremely well. I've had no problems with overheating since installing this fan.
Rog
 
28ACoupe said:
No. The four blade fan does not move more air and is much more prone to breakage than the aftermarket two-blade fans.

Also, they don't look right on these cars. Not as bad as the plastic crap I see on some rigs, but just not right.
Click to expand...
What an OFFENSIVE thing to say!!! I have a 6 blade, BLACK PLASTIC fan & it looks GREAT & by the way, my car AIN'T no "RIG"!!!
Both my cars have been MAFCA's Cars of The Day, in the past.----Bill W.
 

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I have been looking into fans and have not been able to find an aluminum fan anywhere, but in the Mac's catalog they have a chart that shows the amount of air moved at different rpms. It seems that at low rpms the four bladed fan is the best and at speed the two bladed fan is the best. It is interesting to note that on the highway the fan is of little use or like JOE K said:
"And the truth be known - once the vehicle is above say 20 mph, the fan, any fan, actually impedes airflow through the radiator."

So it seems to me that unless you are parading the two bladed Aluminum fan is the way to go,,, and I am looking for one for the trip to the Nationals.
I hope they become available soon.
 
I use to run a 4 blade riveted fan that I bought in a flea mkt. in the 60's,it was extremely heavy,took it off the water pump brgs. were wearing prematurely,run a stock fan,hard to find a good one now.
 
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