[68ragtop]

So, after reading another thread a while back (that I can't find at the moment)
I believe someone said that the optional 68 flex fan was a 5 blade. This 7 blade was on my car, obviously added by a previous owner at some point.

Question is would you run it? Its in great shape, but not sure if it looks similar enough to the original 5 blade. Thinking this one might cool better at idle speeds.
Something I could aways change out in the future I suppose. I also have clutch fan that I already restored, but thinking that might look worse seeing the clutch fans only came on the A/C cars, & mine doesn't have A/C.

Or do I have my info mixed up a bit?

Thanks, 68RT

[Geoff]

That looks nothing like the genuine 7 blade flex fan I have. Mine is 19+" in diam, blades are different & riveted more securely.

Those blades do not like 'flex' blades.

[68ragtop]

Thanks Geoff, So there was a 7 blade option though in 68?
I was surprised reading about all the fan options someone posted a while back. I'll do some more searching, It wasn't that long ago I read something about it.

They are flex blades. there is a part number on it that came back to a chevy forum, but nothing conclusive.

[Bobalong]

Put it on and run it, Whadpyagottolose ? 4 Bolts and your in business, don't like it later ? Well it's only 4 bolts.,

[68ragtop]

I just find it funny that I have owned the car for 16 years & only recently realized (because of another thread) that it wasn't original. It also had a more recent 4 row radiator. I know the previous owner had the car in parades & events like that, so I could see a fan like this flowing a little better at slower RPM's & for sure better than the steel 4-blades. Would my build sheet have a code for the fan blade? I have the PHS sheet, but not the original sheet

68RT

[Bobalong]

Originally Posted by 68ragtop

I just find it funny that I have owned the car for 16 years & only recently realized (because of another thread) that it wasn't original. It also had a more recent 4 row radiator. I know the previous owner had the car in parades & events like that, so I could see a fan like this flowing a little better at slower RPM's & for sure better than the steel 4-blades. Would my build sheet have a code for the fan blade? I have the PHS sheet, but not the original sheet

68RT

Curiosity killed the cat, I read this and had to go downstairs and look at my GM flex fan. My seven blade.Looks much like yours in the pic. And you can tell it's a flex because of the thinner metal used for the blade as opposed to the thicker area where the rivets hold the blade.

The guy I bought the car from 25 yrs ago told me he got it from a junkyard GM
car with a tow package (?) Or maybe it just came from the same AC car he was getting the replacement AC parts from. (second owner got rid of the compressor and a few parts) 70 GTO
Nonetheless, which fan is best is like asking which motor oil is best, or 12V battery. It's been said flex fans are very noisy, don't cool as well . . . .but at the end of the day . . . .well, mine cools as well as expected for an air conditioned car, on a 90 Deg day sitting at a prolonged traffic light.
I have been known to turn the compressor off, and fast idle the engine a little to get some circulation of coolant and air. I get puckered when the gauge climbs north of 200. Never had a coolant dump, or the idiot light come on, but still, I get nervous.

I also have a 4 core radiator, spring in the lower rad hose, and the factory covers and stuff to direct incoming air thru the radiator.

[68ragtop]

I still have to finish bead blasting this fan (as you can see I started) epoxy prime & paint it.
If most would look at it & say, wow, is that ever the wrong fan. I might be inclined to look for a more correct appearing fan before I put all the labor & materials into it. My guess is most people won't know the difference. But might be another one of those parts I can make correct easily enough so my car doesn't get further away form its original configuration than it already is.

I'll have to check that clutch fan when I get home today. I honestly have never even looked for a number on it. I restored it over a decade ago & it's just sitting on the shelf.
I just assumed its not correct either because my car is non A/C

[Scott Thelander]

I dont think being smaller diameter than a correct 19+" fan
it will draw air correctly

yours looks like a camaro/firebird 70-'s

the 7 blade flex came out in 70 for heavy duty cooling fairly sure
I have an NOS one from amember here

5 blade flex for 68 69

[north]

In 69 (68 may be different) GTO's the standard fan was a 19" flex (except the 2bbl engine which had a 4 blade rigid fan if no AC). If AC was ordered you got a 19.5 inch 7 blade clutch fan. The KO2 clutch fan was a stand alone option for non AC cars as well. Another option offered both with and without AC was the KB2 seven blade HD flex fan. It was $10.53 if you didn't have AC and with AC it was optional at no extra charge. I've never seen one in person but I have seven PHS's that include it. I also have two cars ordered with the V82 Trailer provision-medium option which included the KB2 fan.

As I've never seen one I can't confirm the diameter but I would imagine it was 19.5 or 19".

[68ragtop]

So here's the other fan I have. Measures about 19.5" across.
I don't recall where I bought this one. might have been a swap meet many years back.
Would be really cool if this was at all similar to the 68 fans & if by chance a clutch fan would not be completely wrong for a non a/c car.

Thoughts?

[north]

Several of my AC 69’s have that exact fan right down to the pn on the blades. As I mentioned it was optional to have that clutch fan on a non AC car.

Some of those fans with the four rivet square pattern have a fifth rivet in the center holes. As mentioned there is also another interchangeable and also correct clutch fan that has a “T” pattern to the rivets and on those fans the outer blades are more squared off.

To look more correct the aluminum blades and rivets should be natural metal with the steel collar being black paint.

[68ragtop]

Well thats good news! At least I have something that belongs on a GTO & not on a GMC pickup truck I am pretty sure I used an aggressive media to strip this before painting it, so odds of bringing it back to a presentable bare metal condition isnt too good.

[north]

Maybe paint the blades dull aluminum color by krylon, very good facsimile.

One thing I don’t know is if when you ordered a clutch fan oprtion on a non AC car did you get the AC water pump and crank pulleys or did you get the standard ones? I’ve seen several PHS’s for clutch fan option on non AC cars but unfortunately I have never seen a buildsheet for one of those cars (buildsheet id’s the pulleys by code) or at least a virgin car.

The AC pulleys are bigger on the crank and smaller on the water pump to increase fan and water pump speed.

[Scott Thelander]

this may be the KB2 seven blade HD flex fan Mr NORTH speaks of..

Scott

[68ragtop]

Well here's something interesting..... The clutch fan I have installed on this blade is too short. the blades would be too close to the power steering pump. Pulleys?

They are 6.5" & 7.25"

[north]

Could be wrong clutch or the blade is facing backwards?

Scott,

That fan looks like what I’d expect the KB2 to look like.

Here are some pn’s from the 69 MPC:

68-69 GTO FBird 400 9791346 19” 5 blade flex with2 3/8” pitch

69 all V8 HD 9796135 19” 2 1/2” pitch 7 blade flex

69 GTO AC 9784546 19 1/2” 2 1/4” pitch 7 blade clutch

[68ragtop]

Here's a side profile. maybe a 1/4" standoff. not much at all.

[north]

The clutch itself is not a compatible type. The correct type clutch pins the fan right against the clutch cooling fins. This would move it a good 1-1.5” forward solving your problem.

[68ragtop]

any recommendations for replacement? I couldn't even tell you where I bought this one. Too long ago

I was thinking rock auto as they often have AC Delco, but they have only list Hayden & four seasons. I'm not familiar with either of those brands

[north]

Knock on wood but I haven’t had one go bad so I don’t know. I think Ames have correct looking ones.