Viscous Fan Won't Fit

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goldduster360

goldduster360

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I have what I think is a mopar 18" viscous fan but it will not clear my heavy duty radiator on my 73 Duster with 360 engine. The blades hit the top radiator tank. Blade pitch is 2-1/2". Part number of fan is 4140422, not the same number on the current mopar viscous package 4120758 which is I think 4140063. Fan clutch has the standard 1.5" shaft length putting the clutch 1/2 to 3/4" from radiator core.

Can anybody tell me what the blade pitch on the 4120758 package is?

Also, has anybody had the same problem and just went with a smaller diameter fan? The shroud I have is a flipped slant six unit and it fit just fine around the viscous fan I am trying to mount. The stock slant six steel fan is also around 18".

viscous fan.jpg
 
you might be able to space it closer to the engine or maby swap it around so the side that is closer to the radiator would be by the motor. i dont know the sizes and stuff byt saw the post and thought of it lol
 
Its a common problem. The clutch is to longer, longer then factory. Do a search for fan clutch and see if you come up with a replacement number.
 
that is a mopar performance viscus fan. it is a good fan but it lacks the notch cut in the tip of the blades to clear the tank as the fans of the era did for you car. it is a "generic performance replacement" if you will. it works but not on all applications without modifications. you have it setup correctly in the car from the picture. you have 2 choices here. 1 get a proper fan from the year car w/ max cooling or hi performance part #2863216. this is a 7 blade 18 1/2 " fan. this is the stock 340 high performance fan for 1973. by doing this you would not lose much if any, but you gain sainity! 2 would be take a grinder to the fan you have and notch the blade tips back alittle to clear the tank like the factory. this by far would be the most difficult to do as it needs to be the same taken off each blade or it will be unbalanced. i would opt for the first. then you can use the factory shroud and everything will work fine.

upon further reading i need to ask you do you have a factory radiator? if so is it the slant six radiator? what is the number on it? the slant six radiator has a different shroud. a 22" from what i can see. the opening might not work so you might have to check it.......
 
there is a shorter clutch unit available too. Don't know the part number or manufacturer, but there have been posts on here about it. I bought one and mit will allow me to put a clutch fan in my big block duster. I think the fan's made for a Jaguar of some kind. (By Hayden?)
 
that is a option, but the further you pull the fan out away from the radiator and shroud the less effective it will be cooling.
 
When I did the swap I bought a replacement radiator for a Duster 340 from Pep Boys. While not correct in appearance it fits and functions as the original would have. Don't know specific dimensions though but it has the big tank on top like allot of later A-Bodies did. Only deviation is the slant six shroud which does fit around the 18" steel fan and my 18-1/2" viscous unit.

I have an old bubble style wheel balancer, might be able to make a template to notch each blade fairly close and then check it for balance. You can't see it in the picture but I had already scribbed a line where to start cutting them:) I noticed all the pictures in my mopar book showed some early fans with the notches, I always had thought that was for noise reduction not clearance.

Flex-A-Lite makes a generic replacement 18" 7 blade viscous fan that does have the tips notched but from the picture looks like not enough. I think the part# was 5718.

I am guessing looking for a factory 340 clutch blade is like looking for a needle in a haystack.

Thanx for the inputs.
 
dusterdon said:
there is a shorter clutch unit available too. Don't know the part number or manufacturer, but there have been posts on here about it. I bought one and mit will allow me to put a clutch fan in my big block duster. I think the fan's made for a Jaguar of some kind. (By Hayden?)
Click to expand...

Yeah, I think it is the 2765 unit for an 86 Vanden Plas. I heard the snout hole is larger but it may come with an adapter for the smaller mopar water pump shaft.
 
the 340 fan setup might not be to hard to find. alot of times the 318's with a/c had the same fan and clutch as the 340's did. i haven't looked to see if that is the case for 73 or not. i do know that is the case in 71-72. so if the shroud works for the current setup the notch those blades back. you should be able to do it. just take your time and do it alittle at a time. good luck!
 
tyler_s18 said:
you might be able to space it closer to the engine or maby swap it around so the side that is closer to the radiator would be by the motor. i dont know the sizes and stuff byt saw the post and thought of it lol
Click to expand...
wouldnt it blow instead of pulling backwards
 
7demon2 said:
the 340 fan setup might not be to hard to find. alot of times the 318's with a/c had the same fan and clutch as the 340's did. i haven't looked to see if that is the case for 73 or not. i do know that is the case in 71-72. so if the shroud works for the current setup the notch those blades back. you should be able to do it. just take your time and do it alittle at a time. good luck!
Click to expand...

Thanx, I will look into that too, have not been able to find much A-Body stuff at the local wrecking yards in some time, wish I had gone on the hunt for this ten years ago when I swapped this engine in.

I measured it this morning, the Rad. is a 22" piece.
 
ok i just checked on the 318 -340 fan cross refrence for 73. it looks like there were 2 other fans used not common to the 340 but 1 that is the same. the other 2 are slightly different. 1 has a 5 blade setup and the other 7. the 7 blade unit (#2863224) is 18" while the other is 18 1/2" and 5 blade. the 7 blade unit was used on alot of different setups but it is slightly smaller fan. the other 5 blade fan (# 3462139) is used on c body and some e body cars and big blocks and small blocks. that being said if you found any car from 73 that had a 18 1/2 7 blade clutch setup then odds are it is the right fan for you application.

here are the cars to look for for the correct 1973 340 fan setup.

68-71 belveder,coronet,charger w/ 383 or 440 and ac or max cooling.
69-71 fury,polara,monaco w/v8 and ac
70-73 340,hemi without ac
73 dart,duster,valiant,barracuda,challanger w/ 318,340,with ac
73 charger,coronet,satelite,fury,monaco,polara, w/ 318 ac
73 fury,polara,monaco,police car, or taxi w/ 360
 
here is my wifes setup. this is a 340 fan exact same number as my 72 demon 340. i have this installed on my wifes car which is a 318. this setup is a 71 22" 340 radiator. a 71 340 shroud. the fan came from a 70 4 door dart with a 318 and ac. the fan is the same setup as my 70 polara with a 318 as well. so as you see it is not that hard to find one. i forgot to mention i had to do no mods at all to make this setup work. i unbolted the stock fan (5 blade non clutch type) and radiator.then installed the new parts w/ shroud.

DSC02081.JPG


DSC02082.JPG
 
There are 3 different size viscous clutches.
I replaced one on a 71 Demon and finally received the right one from Lordco.
 
doubledemons said:
There are 3 different size viscous clutches.
I replaced one on a 71 Demon and finally received the right one from Lordco.
Click to expand...

his problem isn't the clutch. it is the blades hitting the tank. his fan has no notches for the tank clearence.
 
Thanx again for the info 7demon2, this is extremely helpful. It would definitely be easier to find a fan that fits than notch the one I have.
 
I have a MP fan blade with the jaguar clutch that's going on my new 383 when it goes in this spring. I know that with a big block space between the pump and radiator is tight to begin with, but it looks like I'll be 5/8" from the rad with the clutch. Never thought about the radiator up top. I do have the original fan from my car (72 340 duster) that I'll have to use if its too close at the top. FWIW, both fans are the same diamater, 18 inches. both place the blades the same distance from the radiator, but the oem fan has the little cutouts at the end of the blade. If you do decide to try to trim yours, make your self a template for the removal, so you'll take the same amount off of each blade. If you're careful, rebalancing won't be needed. I'm using a 26" b body radiator and shroud. Hopefully it'll be a little taller than the smaller rad.
 
Dusterdon, the template thing is already in the works:), in case I screw it up or decide to be lazy Flex-A-Lite has a good looking 6 blade fan with only 2-3/16" fan blade pitch versus my mopar at 2-1/2". The Flex-A-Lite part#5718 is an 18-1/4" viscous fan and has the blade tips pre-cropped. They are readily available in fact you can snag one on Amazon for $41.00 including freight.

5700fan.gif
 
Well I couldn't take it. I have drug this fan around for ten years, it's been in three different atticks and I am going to make this thing fit!

I made a template, rattle canned the tips orange and hack sawed the tips off. I used a new blade and made sure it was pulled super tight to avoid any flexing or twisting. I pulled up the tape and moved it over to make a nice sight line for cutting. I used a paper clip to check that the gap was consistent between the tape and the paint line.

I hit the blades with Tal-Strip and then buffed the blades with 400 grit paper to remove corrosion and rust.

templateblade.JPG


cutblade.JPG


chemicalblade.JPG
 
All of the pieces were the same size, that's a good sign I guess. The viscous fluid in the fan clutch should help absorb vibration from any slight imbalance I may have caused from trimming. The blades are aluminum which should make slight variances even less critical.

bladepieces.JPG
 
I found this Imperial thermal standard duty fan clutch at Advance Auto(shuck's, Kragen), part number 215049, same dimensions as Hayden 2705. Hayden has the Imperial catalog on their website too, and the 215049 says "Made in the USA", Yeah!!! Part cost $29.99.

Total height remained the same as the worn out stocker but fan height was 1/4" less which means the fan blades will be farther away from the radiator while the clutch will remain the same distance.

This unit is massive compared to the one installed on this 4140442 mopar fan assembly. Old fan clutch had EATON embossed on it. The viscous fluid had leaked out rendering it useless.

Here is the Hayden site with both Imperial and Hayden numbers:
http://www.haydenauto.com/catalogs/index.htm

Be sure to read up on what "Heavy Duty" means before buying a clutch. I put a HD clutch on a 78 Camaro and it sounded like the fan was going to come through the hood. Unless you do allot of towing or tend to run hot the standard thermal unit is the way to go.

clutchcompare.JPG


fanheight.JPG


clutchheight.JPG
 
Here is a shot of one of the blade tips after being stripped, it has a little tiny mopar logo and another part number, probably for the blade only, assembly number is the 4140442 number I suppose.

If you look closely you can see diamond shaped tool marks on the blade which were made during manufacture.

stripblade.JPG
 
With the worn out clutch attached I give it a spin while clamped in the vice, she spins quite freely with almost no fluid left inside and no shakes! After a fresh coat of high gloss enamel I attached the new clutch to her and she is ready to go for a spin! With the trimming performed and the reduced fan height this should fit with no problems.

fanspin.JPG


fanfront.JPG


fanback.JPG
 
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