Curved fan teeth?

[Kenn S.]

Not to beat a dead horse with my fan questions, but I have a 3992095 fan with perfectly curved teeth. That is, the blades extend to the base of the tip, which is then curved (bent) to the front so that the tip of the tooth is 90 degrees to the fan blade face. All teeth have precisely the same curvature and show no signs of being hammered in a shop somewhere (which you might do if the fan interfered with the shroud).

Is this clearly a modification to the fan? Or were some curved and some not? And if these tips shouldn't be curved, what would the best process be to restore them to their proper configuration without damaging the fan in any way?

This piece was removed from a '71 LS-5 with C60.

[Rich C.]

Re: Curved fan teeth?

That's what they do. Rather interesting piece!!! And rather expensive if you have to find one! That fan was used on 71-73 454 with C-60. Not sure but I believe '70 454 with C-60 looked similar but had a different mtg hole measurement.

'73 LS-4 454

[Kenn S.]

Re: Curved fan teeth?

Indeed. Hard to find is right...

Here's a picture. I'm heading to a local tool and die tomorrow (a large outfit) to see about cold rolling. Since the teeth are curved over and not bent 90 degrees (thinking metal fatigue), they should roll out without problems. If so, other's with bent up fans might use the same approach. The trick will be to match the vertical curvature. Here's hoping it's not rocket science.

[Bill C.]

Re: Curved fan teeth?

100 % NOT correct...

Actually even more dangerous than the correct way.. I think....

Tips should extend up without any bending back towards the engine block...

Billl

[Kenn S.]

Re: Curved fan teeth?

Hard pill, but good to know. Thank you, Bill.

[Bill C.]

Re: Curved fan teeth?

pic of what it should look like ....

[Edward J.]

Re: Curved fan teeth?

Hey Bill do ya miss that big block yet? Kenn, the blades are aluminum I believe and the should not take much to straighten them. Bill, correct me if I am wrong.

[Terry M.]

Re: Curved fan teeth?

There ought to be a date code on one or more of the fan blades. It might be interesting to see what it is.

[Mark D.]

Re: Curved fan teeth?

My wife has curved fan teeth. I've tried to get her to go to the dentist. It runs in her family.

[Edward J.]

Re: Curved fan teeth?

My wife has curved fan teeth. I've tried to get her to go to the dentist. It runs in her family.

Mark, Some one once told me that jet pilots are more likely to have curved teeth,They fly to much with the windows down.

[Rich C.]

Re: Curved fan teeth?

Ouch... When you said they curved back towards engine, I didn't realize you meant THAT much. Be sure to post a picture after you fix. I paid $300 about 15 years ago for a mint one, wonder what they fetch now!

'73 LS-4 454 w/C-60

[Joe L.]

Re: Curved fan teeth?

Hey Bill do ya miss that big block yet? Kenn, the blades are aluminum I believe and the should not take much to straighten them. Bill, correct me if I am wrong.

Edward-----


They are aluminum.

[Kenn S.]

Re: Curved fan teeth?

It's dated, H70.

These days, one of these runs in excess of $400. The fan I really need (3969926) I figure will run a grand by the time I find one.

The fins are aluminum, and the good news for this fan is the curve isn't severe. If the teeth were folded, game over. But I'm hoping to get to a local tool and die today/tomorrow (still trying to get there!) to see what we can do. If the teeth are cold rolled and reformed to the curvature of the vertical axis curve (that is, the curve of the blade from left to right), that should put them back in their original position. Then we shouldn't have balance issues, but to check that, I'm looking into how to spin this (not at home, obviously) to 7000 RPM, if possible, to check balance. At least I'll ask the question. If the laughing can be heard across the street, I'll know that's a no-go. Can't hurt to ask.

Many bent fans are out there, so it'll be interesting. I'll report back what I find when I finally get on my field trip...

[David L.]

Re: Curved fan teeth?

Kenn,

My understanding is that a clutch fan assembly is not engaged at speeds above 30 or 35 MPH (or some speed in that range). The fan does spin at high speeds but it is the wind created by the car going fast that spins the fan but much slower then the engine speed. I don't think that a clutch fan would ever come anywhere near 7000 RPM's.

I have always wondered how an automotive cooling fan was balanced. Are they balanced statically or dynamically?

Dave

[Kenn S.]

Re: Curved fan teeth?

You know, that's right. That's actually a big benefit. Doesn't have to be tested so severely.

Just a guess on my part, but I'd bet statically. I suppose you could use a rig not unlike a balancer for a lawn mower blade. Hmm. I'll ask the tool and die guys what they think. They're usually pretty good about practical ideas like that.