Flex fan

Anyone running a flex fan? If so which one. Direction of rotation? Spacer size? I wanted to run electric fans and will one day but for now going with a flex.

I just have the stock flex fan that came with the car. '73 with a 351c. No fan clutch, just a spacer. (I don't know if they ever came with a fan clutch or not).

Electric is nice at slow speeds, I prefer mechanical at higher speeds.

I prefer mechanical at higher speeds.

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I prefer mechanical for safety reasons. Electric devices are prone to failure, a mechanical one will rotate when the engine is running. (Same reason I got a mechanical fuel pump).

I do have an electrical fan for support that kicks in when the temperature rises in situations like stop and go traffic.

This being said, I am planning on replacing the stock fan with a flex one too in the near future, so I´ll keep an eye on this thread.

Why would you need a mechanical fan at higher speeds? The giant grille should let plenty of air pass through the radiator without any fan when you're moving. The only reason you need a fan is to move air across the radiator when the car isn't in motion.

Mine has the stock 5 blade flex fan. The spacer is 2 5/8" long. I remember it having been replaced because of a recall from Ford. The replacement looked the same as the original. There was an issue with some of them coming apart.

Should we take our cars in if we don't have the new spacer from the recall? Lol

Actually it was the fan that was recalled.

Roy, are you aware of this option: http://www.fordmuscle.com/archives/2006/10/Mark8Fan/ ?

Why would you need a mechanical fan at higher speeds? The giant grille should let plenty of air pass through the radiator without any fan when you're moving. The only reason you need a fan is to move air across the radiator when the car isn't in motion.

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Right! At at speed the flex fan 'flattens out' to help reduce drag.

In my Jeep club we always go back and forth on electric fans. (My jeeps club is older jeeps, we all have mechanical fans) For Jeep'n electric fans work really well at low speeds (4 wheel'n) and have the added advantage that they can be turned off at water crossings.

But many folks complain that their jeeps run hotter at highway speeds. A lot of that, I believe, is the fan is actually blocking air flow. My mechanical fans have a shroud that doesn't cover any of the radiator nor does it force the air to pass by the fan. Electric fans (espeically ill fit aftermarket ones) cover part of the radiator and force all of the air to pass through the fan.

Much of the shroud is just an 1/2 inch or so from the radiator. This, IMHO, basically 'blocks' the air when you are traveling down the highway. And the electric blades also act as a block since the air can't move to the outside of them. (Unlike our fans where there is some clearance between the outside of the blade and the shroud).

again, just my 2 cents worth and something to think about.

Electric fan = good for drag strip. Keep it cool while staged. Turn off during run.

Electric fan = good if designed into the overall cooling system of a daily driver.

I think they are iffy for aftermarket replacement of a mechanical setup.

I am running a stock H code cleveland fan which I drilled to accept the 3/4" water pump shaft on my 460 with an Advance Auto parts 3 row stock replacement radiator. I use an Edelbrock aluminum water pump. I have had a 160, 180 and 195 degree tstat in it. It will hold all of those temps. I settled on the 180. My point is the stock fan seems to move plenty of air if the tune and the rest of the cooling system is up to snuff.

Heard some horror stories on the flex fans coming apart.

I am also of the mind that electric fans (and electric fuel pumps) are just another thing to break.

DONT EVER PUT A FLEX FAN IN!!!!! i have had to relace a hood and a few fenders on friends cars. its metal that flexs...ever try that with another pice of metal? it breaks in half, and when not if it breaks will rip right through fenders, washer boxes or damn near what ever is in the way. If i find a few pics i will post them, the flex-a-fans break right at the rivets. i run a metal fan with a clutch

One other benefit of an electric fan is the reduction of rotating mass. The best performance gains can be made right down the center of the car. Every little bit counts, you not only lose the rotating weight but the aerodynamic drag.

I put a five blade stainless steel flex fan on my 6 banger back in the late 70's just to dress it up. I probably have put about 80,000 miles on that fan with no problems!

I put a flex fan on my car last time I had it on the road. It sucks! Very loud and puts to much drag on the belts. I liked the clutch fan much better. I will be using electric fans when it goes back on the road and the 19" flex fan will be scrap metal.

I ran an electric for years, it was from a late 80's GM car, probably a FWD regal or something. Worked great.

After I sold that car, I switched to a thermostatic clutch fan and never looked back. Cheaper, less thing to go wrong, won't drain the battery if you haven't got a relay inline, etc. The clutched units move tons of air and decouple when not needed. Compared to a stock flex fan, I gained 2mpg's in my 71 Cougar, plus no more noisy fan.

hemi where did you get the thermostatic clutch fan?

But many folks complain that their jeeps run hotter at highway speeds. A lot of that, I believe, is the fan is actually blocking air flow. My mechanical fans have a shroud that doesn't cover any of the radiator nor does it force the air to pass by the fan. Electric fans (espeically ill fit aftermarket ones) cover part of the radiator and force all of the air to pass through the fan.

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Good to think about as I consider an electric fan. Your point about the shroud & fan blocking air flow is a good argument to get a fan that pulls air (rather than pushes), and mount it on the engine side of the radiator, not the grill side. Electric is in my plans one of these days. I've been happy with the electric fans on my '86 Escort and '96 Ranger (and on my water-cooled Suzuki motorcycle). On my Escort the AC went out and the fan stopped working automatically, so I just rigged a manual switch in the driver's compartment. I only ever had to switch it on in traffic jams. My Mustang originally had an automatic, and I'm using the same radiator now that I have a manual trans, so I'm pretty sure that without hot transmission fluid cycling through there my cooling capacity is improved.

But many folks complain that their jeeps run hotter at highway speeds. A lot of that, I believe, is the fan is actually blocking air flow. My mechanical fans have a shroud that doesn't cover any of the radiator nor does it force the air to pass by the fan. Electric fans (espeically ill fit aftermarket ones) cover part of the radiator and force all of the air to pass through the fan.

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Good to think about as I consider an electric fan. Your point about the shroud & fan blocking air flow is a good argument to get a fan that pulls air (rather than pushes), and mount it on the engine side of the radiator, not the grill side. Electric is in my plans one of these days. I've been happy with the electric fans on my '86 Escort and '96 Ranger (and on my water-cooled Suzuki motorcycle). On my Escort the AC went out and the fan stopped working automatically, so I just rigged a manual switch in the driver's compartment. I only ever had to switch it on in traffic jams. My Mustang originally had an automatic, and I'm using the same radiator now that I have a manual trans, so I'm pretty sure that without hot transmission fluid cycling through there my cooling capacity is improved.

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Actually, I was talking about puller fans (engine side). normally 'pusher' fans don't have a shroud.

Here is a random image of a puller fan setup I found on the web.



See how much area is 'blocked' by the shroud? This will limit the amount of air that can get 'pushed' through the radiator at speed.

This one seems to have mitigated this a bit... (it's not a picture, it is an article so if you want to see you will have to click on it). http://www.mustang50magazine.com/techarticles/m5lp_0502_chicane_double_pass_radiator_and_cooling_fan_system/index.html

Basically they use little rubber flap doors in some of the blocked areas. These will get 'sucked closed' when the car is stopped, causing the electric fans to pull maximum air but get pushed open when the car is moving and enough air is going through the radiator that it can all get past the fan. It's a pretty good idea, I had never seen it until today.

Now, keep in mind... this is just my thoughts for consideration I am not claiming to be an expert in this area. I have never used an electric puller fan except in cars where they were part of the original equipment.

Can i ask what is wrong with the regular fans??

In stock cars they should work just fine, isnt it?? A flex fan, if i understand its funcion correctly is a regular fan at low RPM and the blades tend to straight as the RPM goes higher so...

Does this new engines like you guys are using on your cars needs more cooling than the old stock ones?