1966-67 big block fan dilemma

[Gary J.]

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I have two fans with the exact same markings.
1. In the first picture the fan center hole is measuring 2 3/8 inches.
2. In the second picture is the fan center hole is measuring 2 9/16 inches.
3. The center line between holes on the bigger diameter center hole is 3 1/4 inches.
The center line between holes on the smaller diameter center hole is 3 inches.
4. The bigger diameter one will not fit the original fan clutch as you can see holes will not line up nor will the diameter of the hole will touch the fan bosses.
5. The smaller diameter one will line up with the holes on the original fan clutch, along with touching the bosses.
6. The smaller diameter fan is for a 66-67 big block car. Any ideas for the bigger diameter fan is for with the same markings?

[Joe L.]

Re: 1966-67 big block fan dilemma

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I have two fans with the exact same markings.
1. In the first picture the fan center hole is measuring 2 3/8 inches.
2. In the second picture is the fan center hole is measuring 2 9/16 inches.
3. The center line between holes on the bigger diameter center hole is 3 1/4 inches.
The center line between holes on the smaller diameter center hole is 3 inches.
4. The bigger diameter one will not fit the original fan clutch as you can see holes will not line up nor will the diameter of the hole will touch the fan bosses.
5. The smaller diameter one will line up with the holes on the original fan clutch, along with touching the bosses.
6. The smaller diameter fan is for a 66-67 big block car. Any ideas for the bigger diameter fan is for with the same markings?

Gary------


The fan blade assembly with the larger center hole and bolt circle is a 1971+ fan blade assembly. I'm not familiar with one that has the "66" and "H" stampings but, apparently, there was one, Corvette or otherwise.

As I also recall, some pre-1971 NON-CORVETTE Chevrolet applications in the 67-70 period used the larger center hole and bolt circle fan blade assemblies but, off-hand, I don't recall which ones.

The fan blade assembly with the smaller center hole and bolt circle is 63-70 fan blade assembly (in this case, a GM #3888366 used for 1966-67 big blocks and most 1968-69).

[Gary J.]

Re: 1966-67 big block fan dilemma

Joe, thank you for your response. Someone seeing the markings on the bigger diameter and not knowing could very well mistake it for smaller one thinking it would fit. The smaller one is bringing good money right now.

[Ronald L.]

Re: 1966-67 big block fan dilemma

There is a font difference in the 66 too.

[Joseph W.]

Re: 1966-67 big block fan dilemma

The fan with a 3 1/4” hole is for a 67-68 Z28 or 396 camaro.
If original, that’s a rare part.
I think Heartbeat Chevy sells an original for around $1500 but they are out.

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