Fan Clutch Quiz

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03-19-2012, 07:56 PM

wonderful

Burning Brakes

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Fan Clutch Quiz

Hello,
Enclosed is photo of 2 fan clutches. Can anyone tell me which one(s) were used on a small or big block chevy corvette?
All information will be greatly appreciated.
Richard

Last edited by wonderful; 03-21-2012 at 10:08 AM.

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03-19-2012, 08:13 PM

1snake

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The one on the left is a Schwitzer clutch, the other is an Eaton. Both types came on small and big blocks.

Jim

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03-19-2012, 10:37 PM

John BX NY

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Quote:

Originally Posted by 1snake

The one on the left is a Schwitzer clutch, the other is an Eaton. Both types came on small and big blocks.

Jim

i agree with Jim.

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03-20-2012, 01:54 AM

Westlotorn

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I thought the big block used a larger pilot hole. The small block is 5/8

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03-20-2012, 07:39 AM

65tripleblack

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Quote:

Originally Posted by Westlotorn

I thought the big block used a larger pilot hole. The small block is 5/8

Both were used for both engines. The BBC used a shorter shaft in both instances.

Pilot discussion:

http://forums.corvetteforum.com/c3-t...-diameter.html

Last edited by 65tripleblack; 03-20-2012 at 08:41 AM.

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03-20-2012, 07:54 AM

6T7L71CPE

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Quote:

Originally Posted by Westlotorn

I thought the big block used a larger pilot hole. The small block is 5/8

I know my '71 SBC had the larger pilot but I don't know when that started.

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03-20-2012, 10:44 AM

John Meissinger

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Fan clutches

Both styles could have been used, the diffrence is fan mounting to waterpump mounting spacing, the 396 427 is 1 1/2 and the 327 is 1 3/4.
(this is where the fan mounts to the waterpump and the fan mounts to the clutch)
The Eaton was ink stamp dated the other is stamped on the flange after mid 1965..........John

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03-20-2012, 11:00 AM

wonderful

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Here is the back view of the fan clutches.

Last edited by wonderful; 03-21-2012 at 10:17 AM.

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03-20-2012, 08:22 PM

JohnZ

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Quote:

Originally Posted by Westlotorn

I thought the big block used a larger pilot hole. The small block is 5/8

SB pilot was 5/8" and 1-3/4" hub bolt circle until '71, when it changed to 3/4" pilot and 2-1/8" bolt circle. BB pilot was 5/8" with a 1-3/4" hub bolt circle through '70, changed to 3/4" pilot and 2-1/8" bolt circle in '71. Fan-to-clutch bolt circle also changed from 3" to 3-1/4" for '71 on both SB and BB.