5 blade vs 7 blade clutch fan

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Scatpack, my new shroud is on it's way and should be here next Thursday. I have already been talking to my buddy at his fabricating business and as soon as I get my shroud we will be looking for a fix to the gap on top then I will relay that info to Cold Case. In fact I just got off the phone with Brian who is the manufacturing manager and he's just waiting to hear back from me on the fix.
Len
 
Actually, rumblefish is right. The 5 blade offset fan was made for two purposes. First, it moves more air than the symmetrical 7 blade fan. That's why it was sold as part of the performance package in the Direct Connection and MP catalogs. And yes, a side benefit to the offset blades is that they made less noise. But not by much.
Would you recommend the heavy-duty Hayden clutch or the standard Duty?
 
I tried several different factory fans between 99 and 2000,including flex-fans, smaller 6-blades and the large Mopar 5-blade/ viscous drive.
Nothing did the job until I installed the 7-blade.
That 7-blader has made thousands if trips to 7000/7200,slightly underdriven, since ~2000, the T-clutch went on in about 2002, after the viscous couldn't keep up; same year the Hi-flow pump and stat went in.
That 7-blade was already 27years old when I installed it, being a 1973 model.
The only time I hear it is when it cuts in at idle, and I am standing outside the car. My rad is also a 1973 A/C model, off a 318-Dart.
Not a stroker, just a 367HO.
Are you using a standard Duty or a heavy duty fan clutch? I'm wondering if there's a slight performance in using the standard Duty clutch?
 
I have a 7 blade clutch fan in my duster with a 429 stroker with AC, runs cool on hottest days with AC on. The 7 blade fan was a police car fan.

stock 68 426 hemi had a 7 blade clutch fan on it , right out of a totaled 68 roadrunner ----
 
Are you using a standard Duty or a heavy duty fan clutch? I'm wondering if there's a slight performance in using the standard Duty clutch?
In my system;
I use a thermostatic clutch, and a 195*F hi-flo stat; which sets the minimum coolant temp to 195. The T-clutch cuts in at 205*F and the coolant never gets any higher.
The T-clutch will cut out as soon as the rad sees adequate ram-air flow, and when it does, it will leave off sucking power.
Once warmed up, the coolant temp never fluctuates more than a couple of degrees.
Some guys on FABO believe 205 is way hotter than it needs to be and that I could make more power running cooler. They might be right.
But the thing is this; my car went 93 in the Eighth, with 3.55s, set up this way, still hazing 325/50-15 BFG DRs ,they say,thru the traps. Don't bother to ask if I care about more power, cuz I don't. Don't care about more traction either. My car is a streeter.
Forget about power loss. As soon as the car hits 30/35 mph, on a properly set-up system, and a properly tuned street engine, ram air should be sufficient to cool the rad.
At that point, a T-clutched fan should be idling, driven by the wind.
I installed a HD T-clutch from an early 2000s Ford pick-up.
The thing is this; That 7-blade fan, together with the HD clutch, is H-e-a-v-y. I would not install it on a regular 1/2 inch shaft water-pump. I chose a Milodon hi-flo pump for it's bigger shaft (assuming a bigger bearing) and for it's anti-cavitation plate. My pump was installed in 2000 so you decide.....
 
In my system;
I use a thermostatic clutch, and a 195*F hi-flo stat; which sets the minimum coolant temp to 195. The T-clutch cuts in at 205*F and the coolant never gets any higher.
The T-clutch will cut out as soon as the rad sees adequate ram-air flow, and when it does, it will leave off sucking power.
Once warmed up, the coolant temp never fluctuates more than a couple of degrees.
Some guys on FABO believe 205 is way hotter than it needs to be and that I could make more power running cooler. They might be right.
But the thing is this; my car went 93 in the Eighth, with 3.55s, set up this way, still hazing 325/50-15 BFG DRs ,they say,thru the traps. Don't bother to ask if I care about more power, cuz I don't. Don't care about more traction either. My car is a streeter.
Forget about power loss. As soon as the car hits 30/35 mph, on a properly set-up system, and a properly tuned street engine, ram air should be sufficient to cool the rad.
At that point, a T-clutched fan should be idling, driven by the wind.
I installed a HD T-clutch from an early 2000s Ford pick-up.
The thing is this; That 7-blade fan, together with the HD clutch, is H-e-a-v-y. I would not install it on a regular 1/2 inch shaft water-pump. I chose a Milodon hi-flo pump for it's bigger shaft (assuming a bigger bearing) and for it's anti-cavitation plate. My pump was installed in 2000 so you decide.....
Damn. So 21 years of Mopar abuse to that pump....
 
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In my system;
I use a thermostatic clutch, and a 195*F hi-flo stat; which sets the minimum coolant temp to 195. The T-clutch cuts in at 205*F and the coolant never gets any higher.
The T-clutch will cut out as soon as the rad sees adequate ram-air flow, and when it does, it will leave off sucking power.
Once warmed up, the coolant temp never fluctuates more than a couple of degrees.
Some guys on FABO believe 205 is way hotter than it needs to be and that I could make more power running cooler. They might be right.
But the thing is this; my car went 93 in the Eighth, with 3.55s, set up this way, still hazing 325/50-15 BFG DRs ,they say,thru the traps. Don't bother to ask if I care about more power, cuz I don't. Don't care about more traction either. My car is a streeter.
Forget about power loss. As soon as the car hits 30/35 mph, on a properly set-up system, and a properly tuned street engine, ram air should be sufficient to cool the rad.
At that point, a T-clutched fan should be idling, driven by the wind.
I installed a HD T-clutch from an early 2000s Ford pick-up.
The thing is this; That 7-blade fan, together with the HD clutch, is H-e-a-v-y. I would not install it on a regular 1/2 inch shaft water-pump. I chose a Milodon hi-flo pump for it's bigger shaft (assuming a bigger bearing) and for it's anti-cavitation plate. My pump was installed in 2000 so you decide.....
I already picked up a 7 blade Mopar fan... used...maybe I can sell it. Crap
 
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Damn. So 21 years of Mopar abuse to that pump....
like I said any time the car is moving at more than 30/35 mph, the clutch is slipping and the fan, because it presents such a huge resistance to the clutch, it free-wheels.
And what price can you put on peace of mind, stuck in traffic, listening to that 7-blader do it's thing. Spend the money once, on the right parts, and forget about it.
BTW did I mention my rad is from a 73 Dart 318/904 with A/C?
It don't matter how much you spend on a rad; it cannot make the temperature of the coolant in a running engine drop, until the air flows thru it. And, IMO, if you force the system to try to run at 160*F, well, yur gonna need a premium HD system. Whereas my 48 year-old rad is doing just fine, at 205 with a 7# cap.
I run the lo-pressure cap for a few reasons; 1) my system runs rock-solid 205 to 207. So I don't need the "protection", and 2) My hoses last forever. 3) My engine has alloy heads, so those are like big old heat-sinks pumping massive amounts of heat straight into the underhood area, making the job easier on the rad. BUT, it takes that hi-efficiency 7-blader to pump all that hot air downhill and underneath the car. A flex-fan is hopelessly outclassed. The 5-blader on the Mopar viscous clutch never stood a chance. Even direct-driven the hi-efficiency 5- blader couldn't do it. It did fine with the hood open, and engine idling. It did fine over 35mph with the back of the hood raised to let the heat out. But drive it slow, and watch the gauge start climbing. I mean I tried everything I had hanging in my shed; and more.
Not until the 7-blade went on with the Ford clutch, could I lower the hood to where it belonged, and forget about the gauge.
Your results may vary.lol.
 
like I said any time the car is moving at more than 30/35 mph, the clutch is slipping and the fan, because it presents such a huge resistance to the clutch, it free-wheels.
And what price can you put on peace of mind, stuck in traffic, listening to that 7-blader do it's thing. Spend the money once, on the right parts, and forget about it.
BTW did I mention my rad is from a 73 Dart 318/904 with A/C?
It don't matter how much you spend on a rad; it cannot make the temperature of the coolant in a running engine drop, until the air flows thru it. And, IMO, if you force the system to try to run at 160*F, well, yur gonna need a premium HD system. Whereas my 48 year-old rad is doing just fine, at 205 with a 7# cap.
I run the lo-pressure cap for a few reasons; 1) my system runs rock-solid 205 to 207. So I don't need the "protection", and 2) My hoses last forever. 3) My engine has alloy heads, so those are like big old heat-sinks pumping massive amounts of heat straight into the underhood area, making the job easier on the rad. BUT, it takes that hi-efficiency 7-blader to pump all that hot air downhill and underneath the car. A flex-fan is hopelessly outclassed. The 5-blader on the Mopar viscous clutch never stood a chance. Even direct-driven the hi-efficiency 5- blader couldn't do it. It did fine with the hood open, and engine idling. It did fine over 35mph with the back of the hood raised to let the heat out. But drive it slow, and watch the gauge start climbing. I mean I tried everything I had hanging in my shed; and more.
Not until the 7-blade went on with the Ford clutch, could I lower the hood to where it belonged, and forget about the gauge.
Your results may vary.lol.
I'm running a brand new Factory radiator down here in Tampa with a flex fan. Creeps to 190 at long lights. Wanted To loose the flex fan i had laying around for the safety issues i read about on here, also to get a small performance gain noise from the 7 Blade fan won't bother me I probably won't be able to hear it! Lol do you think I need to find a different fan or just use the standard fan clutch? At the same time now I'm thinking the 7 Blade fans going to burn up a water pump! Ahhrrggh!
 
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like I said any time the car is moving at more than 30/35 mph, the clutch is slipping and the fan, because it presents such a huge resistance to the clutch, it free-wheels.
And what price can you put on peace of mind, stuck in traffic, listening to that 7-blader do it's thing. Spend the money once, on the right parts, and forget about it.
BTW did I mention my rad is from a 73 Dart 318/904 with A/C?
It don't matter how much you spend on a rad; it cannot make the temperature of the coolant in a running engine drop, until the air flows thru it. And, IMO, if you force the system to try to run at 160*F, well, yur gonna need a premium HD system. Whereas my 48 year-old rad is doing just fine, at 205 with a 7# cap.
I run the lo-pressure cap for a few reasons; 1) my system runs rock-solid 205 to 207. So I don't need the "protection", and 2) My hoses last forever. 3) My engine has alloy heads, so those are like big old heat-sinks pumping massive amounts of heat straight into the underhood area, making the job easier on the rad. BUT, it takes that hi-efficiency 7-blader to pump all that hot air downhill and underneath the car. A flex-fan is hopelessly outclassed. The 5-blader on the Mopar viscous clutch never stood a chance. Even direct-driven the hi-efficiency 5- blader couldn't do it. It did fine with the hood open, and engine idling. It did fine over 35mph with the back of the hood raised to let the heat out. But drive it slow, and watch the gauge start climbing. I mean I tried everything I had hanging in my shed; and more.
Not until the 7-blade went on with the Ford clutch, could I lower the hood to where it belonged, and forget about the gauge.
Your results may vary.lol.
Sounds like a wicked ride !
 
I'm running a brand new Factory radiator down here in Tampa with a flex fan. Creeps to 190 at long lights. Wanted To loose the flex fan i had laying around for the safety issues i read about on here, also to get a small performance gain noise from the 7 Blade fan won't bother me I probably won't be able to hear it! Lol do you think I need to find a different fan or just use the standard fan clutch? At the same time now I'm thinking the 7 Blade fans going to burn up a water pump! Ahhrrggh!

What thermostat?
 
You may need a 160. It made a huge difference for me. Especially the high flow.
I've never had a high flow thermostat. I always thought you "made" those. Lol. I'm almost ready to get a set of CVF racing pulleys. Mine are so mis matched, the alt belt always ends up being some crap " utility " type..so if I end up getting those, I may overdrive the wp. I have 66 ac one on there now, rubs the crank. But keeps her cool. I doubt it's the flex fan
 
I've never had a high flow thermostat. I always thought you "made" those. Lol. I'm almost ready to get a set of CVF racing pulleys. Mine are so mis matched, the alt belt always ends up being some crap " utility " type..so if I end up getting those, I may overdrive the wp. I have 66 ac one on there now, rubs the crank. But keeps her cool. I doubt it's the flex fan

Stewart Components. They are the best out there. Kinda pricey compared to a three dollar one, but you get what you pay for.
 
Just thought I’d update this thread since I started it.
I ended up using the 7 blade fan shown in my original post, with the MP viscous clutch, on my ‘74 W200, original radiator and shroud. It’s a rebuilt 360, 10.5:1 compression with a little baby cam not worth mentioning. I have a Stewart Components 180* thermostat and I tell ya, the sob does not get any hotter than 180.
I’m driving the truck right now in 90 degree weather all over town, it stays at 180.

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D6C8B788-C457-462F-8562-77A4A14FC982.jpeg
 
I run a 17 inch 7 Blade (aluminum) CLUTCH fan that was available with factory A/C or Heavyduty cooling on the 1965 A-BODY... Along with the TWO Piece "Metal" Shroud...
I have updated the Weak Stock Clutch to the HAYDEN 2947 Clutch and I use a 160 T-Stat ... My 273 Commando runs just fine in the 115° Arizona Desert!
Note: Over the many years I tried "Other" so called performance fans on this 65 B`cuda and nothing cooled as well as this 7 Blade , so I Vote 7 Blade !!!
And the "Heavy Duty" HAYDEN 2947 Clutch !!!
Note2: the reason I tried Other fans was the Stock (smaller) original Mopar clutch units failed a number of times and were difficult to find... till Hayden made the 2947 :)


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