There have been a couple recent threads regarding the 3789562 fan that the 66 and 67 AIMs list for cars with C60 air conditioning. I decided to start a new thread on the simple question of whether the 3789562 used in 66 and 67 had 4 rivets or 5 rivets per blade.
In one of the earlier threads I noted that a photo of the 3789562 can can be found at I ran across this photo while researching the 3789562 fan (the 3789562 fan was used in Corvettes, Camaros and possibly full size cars as well). I believe the photo to be correct for two reasons:
1) In the 1963 section of the Noland Adams book (page 118 of the Second Edition) there is a reprint of the GM drawing for the 3789562 fan that was introduced that year. The drawing shows 4 rivets per blade, in the same pattern as the photo.
2) I have a NOS 3789562 fan that was still in the GM box when I bought it. It looks just like the one in the photo and the drawing in the Noland Adams book.
However, one board member emailed me that he has what he believes to be an original 3789562 fan on his 66 AC car, and that fan has 5 rivets. His fan measures 18 inches in diameter, as does my 3789562, so it is apparently not a base fan.
I note the the shape of the hub in the rivet area on his 66 fan is much longer and less rounded at the end than the 3789562 fan that I have. Aside from the 18 inch diameter, his fan looks a lot like the base fan.
Is it possible that the 3789562 fan design was modified some time between 1963 and 1966, without changing the part number? I'd like to hear from other members who believe they have an original 3789562 fan on their 66 or 67 AC car, regarding whether the fan has 4 rivets or 5.
Note that the seldom-seen 3863137 fan that was also listed in the AIM used 5 rivets, but the rivet pattern was quite different from the 378562 that I have and from the mystery fan on this fellow's 66.
On a related issue, I note that the 1967 TIM&JG says that *all* 1967 fans had 5 rivets and were 17-1/8 inches in diameter. This seems to overlook the AC fans, which were 18 inches in diameter, and perhaps had 4 rivets.
In one of the earlier threads I noted that a photo of the 3789562 can can be found at I ran across this photo while researching the 3789562 fan (the 3789562 fan was used in Corvettes, Camaros and possibly full size cars as well). I believe the photo to be correct for two reasons:
1) In the 1963 section of the Noland Adams book (page 118 of the Second Edition) there is a reprint of the GM drawing for the 3789562 fan that was introduced that year. The drawing shows 4 rivets per blade, in the same pattern as the photo.
2) I have a NOS 3789562 fan that was still in the GM box when I bought it. It looks just like the one in the photo and the drawing in the Noland Adams book.
However, one board member emailed me that he has what he believes to be an original 3789562 fan on his 66 AC car, and that fan has 5 rivets. His fan measures 18 inches in diameter, as does my 3789562, so it is apparently not a base fan.
I note the the shape of the hub in the rivet area on his 66 fan is much longer and less rounded at the end than the 3789562 fan that I have. Aside from the 18 inch diameter, his fan looks a lot like the base fan.
Is it possible that the 3789562 fan design was modified some time between 1963 and 1966, without changing the part number? I'd like to hear from other members who believe they have an original 3789562 fan on their 66 or 67 AC car, regarding whether the fan has 4 rivets or 5.
Note that the seldom-seen 3863137 fan that was also listed in the AIM used 5 rivets, but the rivet pattern was quite different from the 378562 that I have and from the mystery fan on this fellow's 66.
On a related issue, I note that the 1967 TIM&JG says that *all* 1967 fans had 5 rivets and were 17-1/8 inches in diameter. This seems to overlook the AC fans, which were 18 inches in diameter, and perhaps had 4 rivets.
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