70 - 73 Big block with a/c fan question

[Tom L.]

These fans are made using a steel hub with aluminum blades. Part numbers 3969926, 3993889 and 3992095. I own two of them and have actually handled a few others. I've noticed that none of those that I have actually put my hands on or seen in cars don't have any of the "balancing slugs" on the blades while just about every steel blade that I've seen has them. Anyone have a one of these blades with balancing slugs?

I'm wondering if they were actually balanced since the blades are aluminum. Any help would be appreciated!

[Kenneth B.]

Re: 70 - 73 Big block with a/c fan question

My 70 VIN 7601 has none.

[Tom L.]

Re: 70 - 73 Big block with a/c fan question

Thanks Ken, I had hoped more would chime in. Based on what I've seen I'm guessing that these blades were never balanced since there is so little weight away from the center. If they were balanced I'd guess they were spot on the allowable tolerances so balancing was academic to some degree. Thanks!!

[Tom L.]

Re: 70 - 73 Big block with a/c fan question

Didn't get much feedback here or on the CF so I started searching for pics of these fans on google. I found a bunch and all but one I was able to find had no weights added for balancing. I obviously couldn't see the dates on any of the fans to determine if they were balanced some years and not others. Either way, it seems that they were probably at least checked for balance but the large majority must have been within spec.

[Monte M.]

Re: 70 - 73 Big block with a/c fan question

Tom,
I am not sure what exactly it is I am looking for, but I have two of the 2095. I popped the NOS one out of the box and it did not seem to have any kind of balancing weight on it, and the one on my 72 does not either, from what I can see.

Figured I would chime in because so few did.

Monte

[Tom L.]

Re: 70 - 73 Big block with a/c fan question

hey Monte, thanks for checking. The attached pic shows the weight on the blade on the right side. I've seen no blades in person that have it and only 2 through google that do. I guess the low weight of the blades made adding weights on most fans unnecessary for balancing

If someone has a blade with one of these weights I'd appreciate a close up pic and a magnet test to see if it too is aluminum like the blades.

fan.jpg

[Monte M.]

Re: 70 - 73 Big block with a/c fan question

Tom,
After re-reading what you wrote earlier about searching Google, I went back in my personal files. I have pictures of 9 different fans that you are asking about. None of the 9 have weights that I can see.

Just thought I would let you know.

I wonder if there might have been a tolerance. If the fan is balanced within a certain tolerance, they just called it good. Aluminum bladed fans are far more apt to be balanced than a steel bladed fan. Less weight out there, less chance of throwing things out of balance. If a fan was way out of balance, we all know they threw nothing away, it would have had to have been balanced some way. Hence the weights. I GUESS........

Monte

[Tom L.]

Re: 70 - 73 Big block with a/c fan question

I'm sure there is a tolerance but the light blades may make balancing for most unnecessary. I'm looking into this since I have a blade that needs repair. The tips are bent but that's not the real problem. I've straightend them on a couple of fans and it's not that tough. The tough part is the wrecked one. I've been doing some research and I'm pretty sure I can make a blade. The tough part is balancing, if necessary. I have someone that can check for balance but making a correction might be challenging. I need to have an idea of how weights were made and added. BTW, the fan I have does not have the weights I'm inquiring about. Thanks!!