Factory fan blade differences
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Cargo Master
Joined: Jul 2003
Posts: 2,328
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From: Colorado
Factory fan blade differences
I've been junkyard searching lately and have seen different types of fan blades on 70-72's. They are a 5 blade and 2 of the blades are close together and looks off balance. The blade that is on my '67 is only a 4. Does anyone know the difference between the 4 and 5 as far as air flow is concerned? What about the 5 blade with the 2 offset? Thanks!
Elder User
Joined: Jun 1999
Posts: 940
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From: LAT 46.55501° & LON -122
I know the 5-blade offset fan came with the FE's and HD radiator. As for what other engines/radiator combinations use them instead of the 4-blade, I am not sure.
As for the reason for the offset, it might have something to do with harmonics/noise. Since these fans were not intended for fan clutches, Ford may have been experimenting with making the fans as quiet as possible. And for the amount of air they pull, they are fairly quiet compared to newer vehicles when their fan clutch engages. I do know that the spacing between blades seems to make changing the belts a little easier.
As for the reason for the offset, it might have something to do with harmonics/noise. Since these fans were not intended for fan clutches, Ford may have been experimenting with making the fans as quiet as possible. And for the amount of air they pull, they are fairly quiet compared to newer vehicles when their fan clutch engages. I do know that the spacing between blades seems to make changing the belts a little easier.
