71-73 351C Question

Apr 22, 2007 3 Replies
N

I'm putting the final touches on a 351C this weekend and plan to drop it in the ol' mach some evening this week.



It originally had the "X" style 4 blade fan (on the water pump). I found a 5 blade flex-fan and plan to put that on instead.



My question is, I noticed that the blades are not evenly spaced. Is there a certain method for installing this fan? I'm concerned that this 5 blade style might be balanced somehow, because I'm not sure why the blades are offset and not evenly spaced, (unequal number of degrees between each blade).



I would greatly appreciate it if someone enlightened me on this design.



Thanks, Dave


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A

If the fan is the right mount for the water pump and doesn't hit anything you should be fine. The reason the blades are not evenly spaced is to prevent it from having harmonic frequencies. I'm pretty sure all fans are un-evenly spaced. If you look at your old x fan I bet the blades are not at right angles but are slightly off for the same reason.

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N

Thanks! That makes perfect sense to me now. It does match up to the water pump bolt pattern, no problem. You're right, the "X" fan is definitely not at a right angle!

Regards, Dave

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A

Make sure the diameter of the "nose" of the water pump shaft is the same diameter as the "hole" it goes into. I just went thru two water pumps because the bolt pattern lined up but the diameters were not the same. It was installed by a prior owner and I didn't check when I repaired the first failure.

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