396 Fan Clutch

[Michael H.]

Trying to assist a friend on the restoration of his 65 396 car and we've been discussing the fan clutch. Again. He claims all 65-67 big blocks had the short shaft. I'm not so sure though.

Does anyone have anything at all in the way of documentation that shows that the short shaft clutch was used for 65 396?
I'm pretty sure that all the originals I've ever seen years ago had the long small block style clutch shaft.

I don't know if the latest 65 JG calls for the long or short.

[Mark L.]

Re: 396 Fan Clutch

5th Edition JG says "Two fan clutches are used. Either design clutch is acceptable for small or big block use providing the correct shaft length is used." The JG goes on to describe the two designs, unfortunately it does give a dimension for the "correct length shaft".

[Wayne M.]

Re: 396 Fan Clutch

....unfortunately it does give a dimension for the "correct length shaft".

Might have been a typo by Mark, but I see the '65TIM&JG quotes CK in black ink and BB shaft measures 1.5" fron flange surface to blade boss (versus 1.8" for small block CJ). Also mentions that Schweitzer(sp?) type clutches might have a date stamp (starting in mid-65).

Can't help you with my L78; maybe Tony Stein can; he sent all his original stuff off to Pirkle.

[Bill W.]

Re: 396 Fan Clutch

both 17346 & 16120 had the short stepped shaft with no date on the flange and the flat element cover..Bill

[Michael H.]

Re: 396 Fan Clutch

Might have been a typo by Mark, but I see the '65TIM&JG quotes CK in black ink and BB shaft measures 1.5" fron flange surface to blade boss (versus 1.8" for small block CJ). Also mentions that Schweitzer(sp?) type clutches might have a date stamp (starting in mid-65).

Can't help you with my L78; maybe Tony Stein can; he sent all his original stuff off to Pirkle.

Wayne, I'm curious about what a 65 printing of the parts book has on this. If I remember correctly, you have one?

What about the 65 AIM? I don't have one here.

[Jaime G.]

Re: 396 Fan Clutch

I Just Completed A Restoration Of My 65 396.
Short Shaft With Date Code On My Fc.
My Build Date Of Car Is June 30 1965.
Shaft Is Stepped And Fc Is Schweitzer Not Eaton
Jg

[Wayne M.]

Re: 396 Fan Clutch

.... What about the 65 AIM? I don't have one here.

Michael -- '65 AIM UPC 6, Sht A3 (base equip.) calls out clutch asm - fan # 3814560, optional 3814137. L78 section says use same as base for fan and clutch.

July 1/65 revision of P&A30 ( the earliest I have) Nothing on first # under Gr 1.050, but '65 Corvette (ALL, implied by default, because 396 not mentioned) # 3814137 (same as AIM opt.)

The Oct 1/65 (1966 P&A30, first issue) adds (327) after Corvette still with 3814137, but STILL calls out zip for 396 Corvette.

Oct 1/66 (1967 P&A30) same as above but now lists 66-67 Corvette (427) with # 3857530, with overall length 0.22" shorter than "137".

So if the optional SERVICE clutches are the Eaton's, sounds like they used 327 design for '65 L78's.

I'll check my P&A'S up to 1970 tomorrow and advise, if answer not found before then.

[Michael H.]

Re: 396 Fan Clutch

Michael -- '65 AIM UPC 6, Sht A3 (base equip.) calls out clutch asm - fan # 3814560, optional 3814137. L78 section says use same as base for fan and clutch.

July 1/65 revision of P&A30 ( the earliest I have) Nothing on first # under Gr 1.050, but '65 Corvette (ALL, implied by default, because 396 not mentioned) # 3814137 (same as AIM opt.)

The Oct 1/65 (1966 P&A30, first issue) adds (327) after Corvette still with 3814137, but STILL calls out zip for 396 Corvette.

Oct 1/66 (1967 P&A30) same as above but now lists 66-67 Corvette (427) with # 3857530, with overall length 0.22" shorter than "137".

So if the optional SERVICE clutches are the Eaton's, sounds like they used 327 design for '65 L78's.

I'll check my P&A'S up to 1970 tomorrow and advise, if answer not found before then.

Thanks Wayne. That's exactly what I suspected it would show. My late 66 printing shows the same but I didn't have a 65 printing to double check.
The 66 printing definitely mentions the short style 3857530 but it's listed for 65 and 66 passenger car with big block and 66 Corvette with 427. The 65 Corvette listing for all engines is the long shaft 3814137.
That 530 short clutch was designed and released for pass car because of the engine placement in the chassis compared to Corvette. The engine in pass cars was much further forward than Corvette.
The only reason it was brought over to Corvette for the 66 model year was the fact that the big block radiator was now installed at a much greater angle and there was a clearance issue. Not so for 65 396.

I know of two completely untouched original 65 396 cars that have their original long shaft clutches. At the very least, I think this item should be left up to debate instead of set in stone. (although I'm leaning toward the long shaft side)

I've never seen, in ANY GM documentation from that era, that the short shaft 3857530 was spec'd for a 65 Corvette with 396. Without some form of documentation, it's not possible to assume that the short shaft was automatically the correct style.

[Tony S.]

Re: 396 Fan Clutch

Michael. I'll check mine and post a response later.

Take care.
Tony

[Wayne M.]

Re: 396 Fan Clutch

I've never seen, in ANY GM documentation from that era, that the short shaft 3857530 was spec'd for a 65 Corvette with 396. Without some form of documentation, it's not possible to assume that the short shaft was automatically the correct style.

Michael -- when quoting the '65 AIM, I was a little sloppy and should have added this caveat: The UPC L78 Sht 2 has a note "See parts list or bill of materials for additional part numbers released in this RPO that are not illustrated. The components below are (* asterisk) assembled as indicated"

Then it goes though all the UPC sections affected. Under UPC 6, Engine, 6K-1 Fan and Drive -- * Same as Production.

My error was in saying this meant same parts as production, whereas the intention is "ASSEMBLED" same as production. The parts list or bill of materials is never shown in the AIM L78 section, unlike (say) for L84. Example for L84: the following parts installed same as production (3 part#s and descriptions are listed). Then, again "the following parts are installed same as UPC L75" (13 part #s and desc.) And a 3rd time for "The following parts are installed the same as UPC L76" (27 part#s and desc.)

So for L78, we're missing this non-illustrated part sheet, wherein they probably listed the fan blade and clutch numbers (even if only to say installed the same as regular production, in the case of the clutch).

Now the 396 fan blade # 3872972 (not mentioned in AIM) does not show up in my July '65 P&A30; nor in my Oct '65 (1966) P&A30. I see it for the first time in my Oct'66 (1967) P&A30, although if you have a late '66 MY version, it may already be there. This fan was readily available in service until at least Jan '70, along with its cousin the '66-67 427 fan # 3888366.

I can't imagine why it is so late in appearing in the SERVICE list. Were they implying that the 327 fan was good enough for 396 ?

[Michael H.]

Re: 396 Fan Clutch

The UPC L78 Sht 2 has a note "See parts list or bill of materials for additional part numbers released in this RPO that are not illustrated. The components below are (* asterisk) assembled as indicated"

Then it goes though all the UPC sections affected. Under UPC 6, Engine, 6K-1 Fan and Drive -- * Same as Production.

My error was in saying this meant same parts as production, whereas the intention is "ASSEMBLED" same as production. So for L78, we're missing this non-illustrated part sheet, wherein they probably listed the fan blade and clutch numbers (even if only to say installed the same as regular production, in the case of the clutch).

Now the 396 fan blade # 3872972 (not mentioned in AIM) does not show up in my July '65 P&A30; nor in my Oct '65 (1966) P&A30. I see it for the first time in my Oct'66 (1967) P&A30, although if you have a late '66 MY version, it may already be there. This fan was readily available in service until at least Jan '70, along with its cousin the '66-67 427 fan # 3888366.

I can't imagine why it is so late in appearing in the SERVICE list. Were they implying that the 327 fan was good enough for 396 ?

Yes, that's correct. That list would be parts that are "installed same as" production parts but are not the same as production parts. (exhaust pipes, clutch linkage, rad hoses etc) I suspect the section on "fan & drive" would refer at least to the fan blade. (and possibly the fan clutch, if indeed it's different than production)

Is the 3814137 clutch listed anywhere in the L78 section?

I don't know why the unique 396 fan blade isn't shown in the early parts books. There were a LOT of errors and ommissions in the mid/late 60's books so that may be why. It is shown in my July 66 printing of the parts book.

In that same July 66 printing, the clutch is listed as follows.

65-66 Passenger w/396, 409, 427
66 Corvette w/427..........................................38575 30

63-66 Pass & Corvette w/327............................3814137

No mention of the 65 Corvette w/396.

[Wayne M.]

Re: 396 Fan Clutch

Is the 3814137 clutch listed anywhere in the L78 section?

I don't know why the unique 396 fan blade isn't shown in the early parts books. There were a LOT of errors and ommissions in the mid/late 60's books.

No; nether fan clutch or blade assy. part #s or description are found in '65 AIM UPC L78. Probably have to blame ommission on book revisors. Example: the Sept '65 ('66 P&A30) says the base fan "529" is for '61-66 Corvette (exc C.A.C., 396), yet nothing is shown FOR a 396 or for any 427.

Must have had the parts counter guys pulling their hair out .

[Michael H.]

Re: 396 Fan Clutch

No; nether fan clutch or blade assy. part #s or description are found in '65 AIM UPC L78. Probably have to blame ommission on book revisors. Example: the Sept '65 ('66 P&A30) says the base fan "529" is for '61-66 Corvette (exc C.A.C., 396), yet nothing is shown FOR a 396 or for any 427.

Must have had the parts counter guys pulling their hair out .

It appears to have been corrected a few months later. A May 1966 printing shows;

61-66 Pass, Corvette.. Blade assm w/327..exc AC...............3770529

65 Corvette.. Blade assm.. w/396...........................3872792

66 Corvette.. Blade assm.. w/427...........................3888366