Vicous Fan

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71Duster

71Duster

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The viscous fan that was on my Duster rides really close to the rad 1/2" maybe? No matter the water pump if alsways been this way. Does anyone have a measurement of the shaft length on a viscous fan to see if mine is longer?
 
The question is, has it ever hit the radiator. If not, leave it as it is. The thermal switch will read better when its closer to the radiator. I just found a short fan clutch that will allow me to use a clutch fan on my 383 duster. I'll only have 5/8" or so to the rad. Using a factory 340 fan. Should move tons more air at low speeds and idling. Just what I need.
 
71Duster said:
The viscous fan that was on my Duster rides really close to the rad 1/2" maybe? No matter the water pump if alsways been this way. Does anyone have a measurement of the shaft length on a viscous fan to see if mine is longer?
Click to expand...

Being that close (1/2" shouldn't be a problem) make sure that the ends of the fan blades are strong enough that when you rev the hell out of the engine they don't bend forward and contact the rad. It's natural for the blades to bend forward, a little, as they're trying to pull the air through the rad it's just some fans do it more than others cuss they are real flexible.

Terry
 
A 1/2" is awful close.
Can you move anything to get more room?
A good stomp on the brakes or a hard launch could have
you callin a wrecker and a cab.
Could you switch to an electric fan if you have no room?
 
I've run this far for over two years and the unit is fairly old.

Its always been this close -to the point when slideing the fan in the hub scrapes before on the waterpump shaft-

I was always curious if this was the norm. The fan itself is a mopar part with a pentastar and the number 4140063 on it.

The clutch looks old with no Chrysler numbers on it just the word EATON. I was thinking of replaceing the clutch on the car and wanted to see what other people have had luck with and if they make diferent sizes
 
I have the Mopar viscous fan on my 70 Dart and it sits about a 1/2" away.Never had any problems with it being that close.As long as it doesnt hit,being close is actually better.
 
With a 440 in my Duster and a stock type 3 core radiator, I've got about a 1/2" too with about the shortest clutch I believe is available and will fit a Mopar: Hayden #2765 (for a Jaguar).
 
I saw your post on using the hayden 2765 clutch and went and bought one for my duster. How hard was it to install it? Pretty close quarters in there.
 
If your running a shroud , the fan doesn't need to be
that close and will cool a lot better.
If you run it that way with success and are comfortable running
that close to the radiator sounds like your happy with the setup.
I always put a piece of cardboard between the fan and core when
I'm working in that area, has saved many a mishap.
 
The big blocks equipped with air will have a short shaft but if you`ve got clearance there and it all works then I wouldn`t change a thing.
 
dusterdon said:
I saw your post on using the hayden 2765 clutch and went and bought one for my duster. How hard was it to install it? Pretty close quarters in there.
Click to expand...

It is a tight fit. Make sure the rad is out. Bolt the fan to the clutch, then get the bolts started into the water pump. You'll have to hold the clutch away from the face of the WP to get all the bolts started. Once they're in aways, then the clutch can sit flush with the WP. It's very doable, just takes time and some dexterity.

And FWIW, according to the "Chrysler Performance Upgrades" book, optimally the fan (not clutch) should be positioned 1 1/4" from the rad core but 3/4" to 1 1/2" is usually sufficient. And any more than 1/2" space (again fan, not clutch) WITHOUT a shroud will cause it to pull air from other places. With a shroud, 1/2 way in is okay but 3/4 to all the way in is better.
 
I have approximately 1/2" between the front of the clutch and the radiator on my car. But the fan is mounted to the back of the clutch and the twist in the blades does not protrude beyond the front of the clutch making the clearance to the radiator more like 3/4"-1". There is just barely enough room to fit the clutch hub over the snout on the water pump.

I would think if the blades were only 1/2" from the radiator you may not have a mopar fan on the clutch (most GM, Ford and Mopar clutches all use the same size bolt pattern on the clutch the fan mounts to) so it could be from some other car.
 
Just looking at mine sitting on the desk after a day -sitting face down as it says- Its actully leaking a little oil. I;m not too worried about the spacing now but what the best replacement for the clutch unit?
 
Mopar performance (direct connection) used to sell one pn P4120758. Came with fan and viscous clutch. Might be still available. I think it was the same as the original 340 one.


They will leak if you set them down the wrong way (as you found out)
 
Its sitting face down fins up which is correct. My fan is fine and I dont want to replace everything was just wondering if theres a replacement for just the clutch out there
 
Sure, you can get the clutch at your local parts store. They sell non thermal, thermal and heavy duty thermal. I believe I paid $45 for a heavy duty thermal unit.
 
Works for me, mostly what I needed to know was if it was a mopar performance only thing or someone like NAPA can get a hold of it. The NAPA boys here arn't too bright once you say 1971 but I'll try.
 
I don't bother letting the folks at NAPA, Autozone or Advance Auto look up anything. I just go to there on line web page and look up what I need and go to the parts store with part number in hand.
 
I run the Mopar Performance clutch fan on my '69 440 cuda with a 3 row 22" radiator and I have about a 1/4" between the radiator and the clutch fan. The car runs under 190 degrees no matter how hot it gets. The trick to get the cars to run this cool is to run a fan shroud and run the fan blade no more than half way into the shroud. I also have an all orignal '69 340 Formula S Barracuda and it looks to have about a 1" between the clutch fan and radiator.
 
1/2 inch no problem as these fans dont tach up with the rpm , they go a lil slower ,its not like a flex fan setup,1/2 inch fine
 
mc all you can do is mill the water pump another 1/4 inch and realign accessory belts. Im going from electric to viscous 7 blade off an early 400 and with the aluminum radiator Ill have better than 1 inch clearance,wouldnt work that way on my 67 notchback barracuda though with the 3 row radiator.this ones a 71 dart with serious overheating issues due to it just being used for race purposes, if even has a huge chevy shroud on it thats coming off tomorrow,jegs has an aluminum radiator they guarantee it alone will cool a 700 hp engine adequately, we shall see as the core is only 1 1/2 thick.
 
Well I'm back at square one. I went to NAPA tried all 3 clutch units.

The actual finned area is about double the width of mine no big deal but ALL are too long. The stock replacement is WAY to long the heavy duty is close but just a little too long and the centrifugal is the worst.

The parts guy said there brand is made by 4 season. What else is out there?
 
71Duster said:
Well I'm back at square one. I went to NAPA tried all 3 clutch units.

The actual finned area is about double the width of mine no big deal but ALL are too long. The stock replacement is WAY to long the heavy duty is close but just a little too long and the centrifugal is the worst.

The parts guy said there brand is made by 4 season. What else is out there?
Click to expand...

I was in need of room too. so...

OK did some research a while back on this, so this is what I have come up with from a spec list from Hayden. They make most all of the fans on the marrket. I still have a new Mopar unit too that I may sell. Never used.

You may need a 5/8 to 3/4 reducer bushing? Some of the pumps do not come with them.:read2:


HD Applications .75
2765 1.09 depth is thermal HD This gives the most room.
2747 1.62

non thermal .63
1705 1.53
1706 1.75
1707 2.03

thermal .63
2706 1.75
2707 2.03
 
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