71-73 351C Question

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nospam - 22 Apr 2007 21:41 GMT

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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Ashton Crusher - 22 Apr 2007 22:30 GMT

>I'm putting the final touches on a 351C this weekend and plan to drop it in
>the ol' mach some evening this week.
[quoted text clipped - 12 lines]
>Thanks,
>Dave

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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nospam - 23 Apr 2007 00:11 GMT

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

>>I'm putting the final touches on a 351C this weekend and plan to drop it
>>in
[quoted text clipped - 22 lines]
> bet the blades are not at right angles but are slightly off for the
> same reason.

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Ashton Crusher - 23 Apr 2007 02:40 GMT

>Thanks! That makes perfect sense to me now.
>It does match up to the water pump bolt pattern, no problem.

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.

>You're right, the "X" fan is definitely not at a right angle!
>
[quoted text clipped - 27 lines]
>> bet the blades are not at right angles but are slightly off for the
>> same reason.

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