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What is the correct fan blade for a 1970 LT1 which uses Alternator part # 1100884, 61Amp
GM Part number?
I have come across reference to a stamp of "3" on the backside of one of the blades, perhaps the widest blade
My opinion is a no as the leading edge of the blade has a notch and originals do not have that. See photo of an NOS over the counter service fan. GM pert number 800594 see photo
Plus a 1100884 alternator would be an open frame the one shown is a closed frame. See photo
Service replacements are often different than originals.
The difference that jumps out is the notch on the widest blade
The replacement has the small dimples on each blade
That notch is on the upper tip not the leading edge. The one your showing could be a GM fan but since it is on a alternator that is a fake. One would think is there anything real about what is in the photo. The fan I have posted was used from 1968 thru 1979 plus that box is from the 1970's. I would trust that more then what is in your photo. A real 1100884 would sell for $800 to $1300
I have an Alternator off a 72 passenger vehicle and I was just looking at it and it appears to be just like 800594. See images below
I had always heard that the LT1 had a different fan because of its high RPM and resulting issue with noise. But it seems the LT1 had a generic fan....Is this true?
The first photo I posted is apparently from a 1970 LT1, but from a Z28. I guess they used a different fan... And the alternator itself is not an open design like the 1100884. But the focus of this post is the fan, not the Alternator. I have an Alternator off a 72 passenger vehicle and I was just looking at it and it appears to be just like 800594. I need to do a more careful comparison though.
The NCRS judging guide (pg 147-150, 6th ed.) indicates:
#1100884 (61amp, code NT) is appropriate for all Corvettes with A/C and LT-1s.
fans like yours with the wide bare fin (lower right) and like PJO's pic with narrow fins are both seen. The text indicates that the wide bladed fans may have been used on LT-1s and LS-6s to break up the noise at high rpms ... however usage for both is seen on all engines, so it's not looking like a hard and fast engine relationship to usage.
the pulley for LT-1s and LS-6s (not '72 w/AC) is a machined pulley from steel that looks like what you have.
As I look at Barry's70LT1's fan, its much thicker metal. It looks aluminum. The raunchy '72 fan I posted is very thin.
That image posted by PJO, is from ebay, here is another view showing its thickness. Still, Barry's looks thicker. Both Barry's and PJO/ebay look thicker than the raunchy '72 fan
As I look at Barry's70LT1's fan, its much thicker metal. It looks aluminum. The raunchy '72 fan I posted is very thin.
That image posted by PJO, is from ebay, here is another view showing its thickness. Still, Barry's looks thicker. Both Barry's and PJO/ebay look thicker than the raunchy '72 fan
The Guide does not address thickness of the fan, just that they are stamped steel, zinc-plated, but I agree the thicknesses do look different. Barry's fan looks extra-thick...
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1970 LT1 Alternator Fan
