3864480 1966 L72 Pulley
Have been looking for an original 3864480 pulley for some time, this one just popped up on eBay, appears original... Opinions? thanks
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Re: 3864480 1966 L72 Pulley
Don------
I have no doubt it's an original GM #3864480. One thing I don't like about it, though, is the pilot hole. It looks a bit "irregular" to me as if it might have been slightly modified. Of course, it could just be the photo. I do believe that the surface grinding in the area of the pilot hole is original, though, as it seems to underlie the part number stamping. A 5/8" shaft has to fit PERFECTLY in this hole or the pulley is scrap.In Appreciation of John Hinckley -
Re: 3864480 1966 L72 Pulley
Thanks JoeComment
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Re: 3864480 1966 L72 Pulley
Follow-up, I enhanced the photo and enlarged the center, it definitely appears to have been modified/enlarged. I cancelled the buy and will continue the search...
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Re: 3864480 1966 L72 Pulley
Don------
By the way, the reason that the pilot shaft hole on the pulley is critical is because that's what centers the pulley on the waterpump. The pulley cannot be centered by the 4 retaining bolts. So, if the pilot hole is oversized, even by a little, the pulley will rotate in an eccentric manner. That's a prescription for all sorts of problems. You will note that on a properly configured pulley the waterpump pilot shaft will be a very snug fit in the pulley pilot hole. That's important.
I know of no practical way to repair a pulley with an oversized or modified pilot hole.In Appreciation of John HinckleyComment
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Re: 3864480 1966 L72 Pulley
Thanks Joe, Yes I was aware the center shaft hole is critical, and thanks for pointing that out on your review of the photos. I was so surprised to find a 3864480 on eBay that I forgot to fully examine the photos! Hence I cancelled my purchase and that pulley is now back on eBay. All of the sudden there is Another one on eBay, this one has no obvious damage to the pilot shaft hole, but the buy-it-now is $800. So, the search continues... thanks again.Comment
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Re: 3864480 1966 L72 Pulley
Don------
Whoever messed with the pilot hole in the pulley you originally pictured converted a very valuable pulley into a piece of scrap metal salable only by the pound. If its eBay price was relatively low, I'll bet the seller knew that.In Appreciation of John HinckleyComment
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Re: 3864480 1966 L72 Pulley
I have been looking for one of these for a few years. I purchased one I thought was original, but I am not sure. If there is anyone that could post (1) a known reproduction with commentary on features that make it a reproduction piece, (2) an absolutely certain original, or (3) better yet a side by side I would appreciate it greatly. I need to know I have what I need or I should keep on looking. Thanks.Comment
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Re: 3864480 1966 L72 Pulley
Larry,
Wouldn't it be easier for you to post up some nice, clear pics of the pulley you purchased? Those with knowledge will be able to tell you what you have...just a thought.Leif
'67 Coupe L79, M21, C60, N14, N40, J50, A31, U69, A01, QB1
Top Flight 2017 Lone Star RegionalComment
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Re: 3864480 1966 L72 Pulley
The pulley is on the car. The front where the fan mounts and backside would be hidden in the pics. If I have to pull it to get some good pics I will. But hopefully I can get a side by side comparison and not have to remove it right now. Thanks.Comment
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Re: 3864480 1966 L72 Pulley
On the left is the Paragon Repo with the number stamped in the front. The one on the right is an original from GM with no numbers. Or at least no numbers that I can find.
JRComment
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Re: 3864480 1966 L72 Pulley
The two original pulleys from Joe and Don differ from each other. Most noticeable is the "lip" on the underside of Don's being absent on Joe's. This part number was used in 65 for the L78 also, correct? Joe, do you know what the original application was for yours? Was there a change in the part for 66 year models?Comment
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Re: 3864480 1966 L72 Pulley
The first photo in this thread that I posted earlier this year is of an original pulley but the center hole had been damaged. The pulley I recently found has the same overall appearance and configuration and matches other originals I have seen. All that I have found or seen that were reported to be original had the 3864480CV stamping. It was my impression from talking to others about this pulley over the years that the 3864480CV stamping was present on original parts. Good luck with your search
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Re: 3864480 1966 L72 Pulley
Larry, I have no idea where the used pulley originated or what year. On the front there are issues on the Paragon pulley that differ from the original other than no part number stamped on the original.
JRComment
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