1972 LT1 Engine Fan
I went to Carlisle this year and a vendor had a fan marked "1970-1972 LT1/ZR1" on it. I asked what the differences (if any) that this fan had with the base motors fan from either 71 or 72. The vendor did not provide much information, other than stating that he knew it was different and that it fit the LT1/ZR1 specifically. Can anyone shed any light on the differences? Thanks in advance. Greg
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Re: 1972 LT1 Engine Fan
Greg-------
First of all, there is no such thing as a fan blade assembly applicable to "1970-72 LT-1/ZR-1". That's because 1970 fans had a different fan clutch bolt pattern than 1971 and later so the two year ranges are definitely not interchangeable.
Notwithstanding the above, the 1970 fan blade assembly for LT-1/ZR-1 was GM #3888366. This same blade assembly was used for base engine cars, except those equipped with C-60. This fan blade assembly is a 5 blade, 17-1/2" unit with the number "66" stamped on the hub section. Some 1970 LT-1 may have used the same blade assembly used for base engine and L-46 with C-60, GM #3955182. This is a 7 blade, 17-1/2" unit with the part number stamped on one of the blades.
All 1971-72 LT-1/ZR-1 without C-60 used fan blade assembly GM #3991420, the same blade assembly used for base engine cars without C-60. This was a 7 blade, 17-1/2" unit. 1972 LT-1 with C-60 used fan blade assembly GM #3991427, the same blade assembly used for 1971-1972 base engine with C-60. This was a 7 blade, 17-1/2" unit with a blade pitch greater than the 3991420.
So, from the above you can see that there was no fan blade assembly used for ANY 1970-72 LT-1/ZR-1 that was unique to that application. I expect that folks like to label such fans they have for sale as LT-1/ZR-1 since the fact that the fan is so-applicable "automatically" commands a higher price.In Appreciation of John Hinckley -
Re: 1972 LT1 Engine Fan
Joe, Thank you for the excellent reply! I thought that there would not be a difference. I was wondering one thing though, in your post you mention that the non a/c car had a 7 blade fan, I was under the impression that it was a 5 blade fan. Could you please clarify. Thanks again, GregComment
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