For those running a Flex fan w/o fan clutch etc. What size fan did you go with? I have a feeling that replacing the stock fan with the same siz flex fan will cause some clearance problems with the shroud.

By the way, does the flex-fan do the job keeping things cooled off? I have heard that they can be noisey... any problems there?

Thanks,

kdlp

 

16" i'm pretty sure or is it 14", just in case just measure the opening in yer shroud. i used a 2" spacer on mine. i've had mine on for 12yrs now and i run cooler w/it than the clutch fan and i don't hear no noise. u can see it on my pics

 

Be careful with a flex. Get a very high rpm rating as you can throw the blades off. Believe me, I know what a broken fan blade can do to a Vette.

 

I agree with rosslato, I believe mine is 16". Mine is a Flex-a-lite I think, rated to 6000rpm, which is fine for my motor. Your local parts store will know the correct application. Cooling capabilities are better then stock fan (I think the clutch was goingon mine, and this was cheaper then a new clutch), although the noise is intrusive, but that just means I need a louder exhaust

I do plan on switching to electric fans someday, but there are other projects first...

trw

 

I used a 17.5 inch Stainless Steel flex fan for 10 years. I tried the 18 inch, but even with proper shimming on the trany tail shaft i felt that it was just too close to the shroud and just a little motor torque would cause it to hit.

I used a 2.5 -3 inch spacer to get the blades inside the shroud. It work much better than that heavy piece of junk clutch fan.

 

Think there are some rated at 10,000 rpm....but I would not trust any....

 

In some car magazine in the last year or three, a comparison of the HP difference between stock, electric and flex fans was studied. Conclusion was a minor difference and the stock was actually the best. Don't remember if it looked at cooling, and don't remember magazine. Anyone else remember?

 

My 81 had a small flex-a-lite on it when I bought it (#1017 or 1018: one specified for 4-6cyl or low clearance apps). I wanted something a little bigger, since the engine would warm up when driving around town on hot days. I bought the #1318 (18 1/4"), and it does cool better than the undersized one. I do notice some more fan noise, but it's not enough to bother me. It sounds like most other Chevys I know.

Sorry I can't compare to stock for you.

Oh, if you do go with flex a lite, heed the warning about wearing gloves & long sleeves while installing. Them buggers is sharp!!

Good luck!
Dan

 

Yes mine was the 10,000+ rpm rated and I ran my motors to 7500 rpm all the time and I put nearly 100,000 trouble free miles on that fan. The fan spins faster than the motor


That's total BS! I can do a study and have the results come out how I want them too. HP drag of a fan is caused by how much air it moves and how efficient the blade design is. So a flex fan like I had might use the same HP, but what they failed to tell you is that the flex fan is moving more air for increased cooling. Or you could run less of flex fan and reduce the HP required.

This test also didn't bring up accelleration and decellaration of a heavy clutch fan. For junk stock L-48 or even L-82 and driving like grandma it probably doesn't matter. What happens when you install a shift kit in your automatic and get nearly instant shifts. Big ol heavy clutch fan doesn't want to change thousands of rpm instantly. So your going to be smoking your belts or even spitting them off.

Let's go to the next level - electric fans. You have an amp load on the alternator, but it does bother the fans how much you up or down shift because they are not a spinning mass on the motor.

I also thought that my 79 clutch fan was extreemly noisy as you rapped the motor up

 

Thanks for the info... I think I'll probably go with a Flex-a-lite for the near term. I would like to hang a couple of electrics behind an aluminum radiator, but that's going to have to wait for a while...

kdlp

 

I have a 19.5",6 blade, stainless flex fan, spacer and bolts. Worked OK on an El Camino w/o AC. Want to try it?

 

Taijutsu,

Hey I appreciate the offer, but I don't think it's going to fit. I think I measured my stock fan at 19" yesterday and my initial fear was that the Flex-fans would flex into the shroud as the rpm's went up. I think I'm going to have to find a 16" or 17".

Thanks though....

kdlp

 

Flex fans work great. Have used on for years on my Olds that I regularly take to 6000 rpm on the drag strip with no problems. It's the largest one that they make rated for 10,000 rpm (19" I think). It is somewhat noisy, but they do make a heavy duty version that has offset blades to reduce the noise. Flex-a-light makes it, I think.

 

I put one on my car. They look good. I read the reports about the howling and thought how bad can it be? It was bad enough to go back to stock after 2 short drives.