On a basically stock built 440 where horsepower loss/gain is not a concern but the best cooling efficiency is, what radiator fan type is a better choice, an original type fixed fan or a clutch fan? The 440 in my 67 GTX has a 7 blade clutch fan on it now (not sure what from) rather than the original fixed blade fan it should have and I was debating whether or not to put a fixed blade fan with spacer back on it, leave the clutch fan that is on it or maybe use a Mopar Performance 5 blade fan and clutch that I have in my parts stash. I am not currently having any cooling problems but then again I haven't had the car very long and have only driven it a few times all of which were short distances. I haven't driven it in any situations that might cause overheating like extremely hot days or long highway drives but I would like to make sure I have the best cooling set-up for when I do.

I can tell you the MP clutch fan package has about most "loose" oe clutch the folks who set the part up could find. (6 cylinder B van, if I remember correctly?) It's not set up for max cooling, but for the least power loss of the parts they had on hand back then. I personally like the 5 blade fan that came with that kit but the main reason is because it's noticeably less noisy than the 7 blade fans, not because the cooling is amazingly great. I've currently teamed it up with a tighter rv spec clutch from the parts store 'cause I am spinning everything slower with an underdrive pulley. Don't do what I did and use an underdrive crank pulley and life will be easier.

The fan clutch slips to reduce power loss....a fixed fan will draw more power from the engine but will give you more cooling at lower vehicle speeds.

a long highway drive doesn't need a fan at all. If it runs hot over 40 mph it's a water problem.

A flexible fan is never a good choice for a street car. It's hard to beat a 7 fixed blade factory fan with a clutch and a factory shroud. Your milage may vary.

That wont work down here in Southeast Tx LOL, I run a 7 blade direct Flex a lite blade, it keeps my car 180ish all day long traffic or moving, air temps over 100 deg, 512cid with COLD AC .

Above 35 the air flow through the core from vehicle speed is much stronger than the fan provides.

I am not going to argue, I know it for a FACT.

I like the clutch fan. It cools well when needed (low speed and hot) and releases when not needed (rolling and cool).

Fixed fans are noisy when rolling and burn a little more fuel if that matters.

The clutch also seems to act somewhat as a speed governer. It helps prevent the fan from overspeeding and coming apart.

If your 7 blade + clutch cools OK I would keep it as is.

I currently run the Bouchillon 6 blade fan and their thermal clutch on a warm 496. Works fine. Previously I ran the 5 blade MP setup and that worked OK with more heating at a long standstill & AC running vs the Bouchillon.

we did fan/ radiator testing for Ma Mopar 40-50 years ago on the famous BAker Grade (Death Valley turn off area) 5-7 miles upgrade

You really need the fan clutch and 7 bladed fan- 9 bladed on reverse direction serpentine like my Magnum
Mopar speced different temp cut ins for different vehicles
The late one I remember we went from a 185 degree 7 blade 3" pitch to a 195 9 blade 2 1/2 inch pitch (serpentine)
Worst case was stop and go up hill in heavy traffic WITH A TAILWIND
we found the air would recirculate through the radiator then get blown back in front of the car or truck and go around again
MOPAR changed the Valance/ spoiler designs
Worst case around town is stop and go with the AC on
The output of the AC goes way up with a flex fan or a 5 blade steel fan
this is also where an electric pusher is helpful
Put your shop fan in front of the radiator on the dyno or not and turn the AC on with a temp guage/ probe turn then fan on- see/ feel the difference
so- plug all the holes in the core support
add at least a factory valance
run the clutch fan with the appropriate fan for your radiator/ shroud
do run a shroud with the fan in the proper place in the shroud
The hardest thing is getting the hot air out of the engine compartment
coated headers/ exhausst really helps
the valance creates pressure in front of the radiator and low pressure behind the radiator and prevents the tailwind problem
BTW I have a switch in the spedo drive that - thorough a relay- turns off the electric fan around 28mph another relay turns it on when the AC head pressure goes up under 28 mph (most of the time keeps the noisy fan clutch fan from coming on-- the 7 blade is noiser than the 9 blade
GM is using an 11 blade I'm going to try
hope this helps
do you run a selonid that bosts idle when ac is on?
water pump with solid or plated stamped impeller helps
18 pound cap and good hoses

The Baker grade on I-15 is 14 miles form the bottom, at Baker, CA. to the top of the last hill past the overpass half way up the grade
I've made that trip many times in all the different seasons, August in mid after noon is the worst
As far as the best fan set up the for your car the factory 7 blade with a good clutch is the cats meow

14 miles
In the summertime when there is a wreck it's like forever
much worse than the Grapevine or the road from the 10 to 29 palms
I did not mention the load that working the torque converter puts on a radiator- shift down if stooped put it in neutral and rev it up a little
I've seen new stock rebuilt 440 motorhime motors burn up
never gets hot in Eastern Oregon does it


another test we did was on transmission coolers
note that the factory later went to 3/8 line and 1/2 inch on the diesels
one poster figured out the flow difference but I recommend 1/2 inch line and a 100 plate and fin cooler with 1/2 in and out
the two together can cut the pressure at the trans return point by 45 lbs
that's a lot less restriction
you should be able to fill a quart jar in 20 seconds idling in N (or P with the Transgo Pat valve)

CSK I agree.I run an 18 inch stainless flex fan on my 65.Been on for over 20 years and works flawless.ran a flex on my Jeep plow vehicle.Daily driver to the tune of over 100K and no problems.In fact the jeep ran a bit cold.The 65 built 440 runs 180 all day all the time.Only fan I ever saw broke was the stocker one on my 65 years ago.Rocky

nothing is foolproof
Ive seen flex fans come apart at the rivets and go through a hood
fan clutches come off the shaft (after negligent ignoring the wobble and loss of fluid
does NHRA a;;pw flex fans?
remember when you could get flex fans with AL blades
even al blades for clutch fans- have not seen them in years
I think that we can all agree that cheap plastic blade fans suck

I now run a 16 inch Spal 2 speed fan only as a pusher.9:1 534 inch 2nd gen blown Hemi.No shrouds and no problem.Runs at 170* or up to 185* on a 95* day sitting in traffic.