viscous fan drive clearance problem

[bbeckwith]

Hi all,

I have been working on the Duster for some time now and was in the process of installing the rad, shroud and viscous fan drive and fan today. I switched the 340 from a stock water pump to a mp pump, and march underdrive pulleys. I pulled a couple of viscous drives from the junkyard and a 18 1/2" fan off a /6 car, cleaned them up, and went to install. Seems I only have about 3/16" clearance from the viscous drive fins, and the radiator fins. Seems too close for comfort to me. Are there different length viscous drives available? or is my problem with the mp water pump? Could it have a longer snout on it? I am leary of trying to run it this way but I'll be damned if I'll go back to my old direct drive fan. Any suggestions appreciated.

[creative1]

i am sure these are available with different length shafts , but i dont know how you would go about finding them other than trial and error. youre right though, about the clearance. i think i would want at least 1/2" between the fan clutch and the radiator. i wouldnt think that the performance pump would be any longer, as that would pretty much eliminate the "bolt-on" theory.

[dwc43]

The mp pump is stock lenght and is not your problem. On some of March under drive pulleys they are thicker around the pump mount. I have seen a warning from them to make sure that the pump pilot sticks completely through the pulley and into the fan for support. So they know some are too thick. So I'd check that first. And creative is right. Rule of thumb is minimum 1/2 inch fan to rad clearence. I also think he's right on the diffrent lenght clutch shafts too.

[bbeckwith]

jeez, I was hopin to save a buck or two using a junkyard viscous drive, may have to hit the parts store and check and see if I can get one with a shorter shaft. by the way, dwc43, the March fan pulley is thicker than the original but the pilot does go all the way through the pulley. I think it pushed out the fan only maybe 1/8" or so. Will check out some other viscous drives tomorrow. Thanks guys