68 BB Fan and fan shroud numbers

[Dale P.]

I am slightly confused on the correct GM part numbers for the fan (itself) and the fan shroud.
One place calls out 3938940 as the correct fan shroud number othes call out a different number same with the fan itself

this all boils down to needed to confirm that the one in my car now is correct (doesnt flow air very well) besides the relationship between the fan the shroud just doesnt look right. currently what is in the car is in fact the 3938940! so if this is incorrect i will need to replace, if so who has the better quality part?

[Ray K.]

Re: 68 BB Fan and fan shroud numbers

Dale,
Based on the fan blade article prepared by Joe Tripoli in the last issue of the Corvette Restorer, the fan blade is identified as #3888366 and had application for all 1968 engines 327 and 427 with or without Air Conditioning. This is a 5 blade fan 17 & 1/2" diameter. The shroud #3938740 is listed in my '69 P & A catalog and seems to be the correct choice but the description information is not very clear. Also, there are fan shroud extensions listed #3942740 ( upper ) and #3942743 ( lower ) for '68 cars with A. C. Would suggest consulting a 1968 AIM to verify what should be correct for your Corvette.

Ray

[Ronald L.]

Re: 68 BB Fan and fan shroud numbers

Dale, the service part number were added in after '68 production, however the part its self did not change.

Perhaps you have a mid year shroud installed.

Each piece of a legitimate GM 68 BB shroud had the part numbers molded into it.

AFAIR 3888269 3886887 3911110 are the original component part numbers, regardless - they will be in the AIM.

[Scott R.]

Re: 68 BB Fan and fan shroud numbers

1968 Dec. assembly date. I am trying to verify what fan shroud part numbers. the lower sections check out with the TIM guide (3935571,3935572, and have the General Tire logo) The upper is 38882xx hole is drilled thru last 2 digits of part number. There is a yellow stenciled pt no. of 3938940 on the drivers side lower section. The TIM specifies 3935569, and a extension of 3956089. I am confused. Scott

[Ronald L.]

[Scott R.]

Re: 68 BB Fan and fan shroud numbers

Ok, I made an error, December 1967 assembly date, Scott

[Gary B.]

Re: 68 BB Fan and fan shroud numbers

You need to remember GM was "trying" all sorts of things to improve the cooling of the cars. 1969 went with a larger radiator which helped immensely. Every few months changes were made, recorded in the Assembly Instruction Manual's. How quickly those changes were made is hard to tell, as un-molested "original" 68's is kind of like chicken lips.
My April 1st, 1968 built car, has the fiberglass shroud similar to the 67's used. See pictures attached, which downloaded upside down. It's like what the AIM shows on UPC L36, Sht A13. Upper Ring #3935569, 3935571 & 2 LH & RH sides, with a bolted on lower ring 3887428. The change column show's this sheet was redrawn, but cannot read the date.
The AIM calls out fan 3888366 for all engines.
I have another AIM in the shop, I'll look at it in the morning, see if the date is more legible.
Gary B

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[Gary B.]

Re: 68 BB Fan and fan shroud numbers

If you look at the L36 Section of the Assembly Instruction Manual (AIM), it call for the fan to be "Production Part". That would be 3888366.

On 7-7-67, L36, Sht. A11 was redrawn and revised. It reflects a metal fan shroud (3919741 & 2, 3932997 front) similar to the small blocks. On 8-16-67, the shroud changed to 3932995, 3932996, 3932997 all spot welded together. The pictures shows the shroud being deeper, extending closer to the engine.

On 12-1-67 Sht. L36, Sht. A11 was redrawn and revised. The new drawing reflects a fiberglass shroud, similar to the pictures posted above.

Sheet L36 A13, was drawn 11-27-67, released 12-4-67. 3935571, 3935572 for the sides, 3935569 for the top, and 3937428 ring that bolts to the lower sections. Pictures posted above reflect that shroud. Don't know the exact date when this started being used on the assembly line though.

Also remember, GM issued Technical Service Bulletins trying to fix cooling issues. Look those up, as you might have a hybrid design.

Gary Bosselman

[Scott R.]

Re: 68 BB Fan and fan shroud numbers

Thank you Gary, I am missing the top metal bracket that attaches it to the radiator support, and the lower metal extension ring (3937428). If anyone has the upper attach bracket part number, or has one I would gladly purchase it. This is my first corvette, and I am trying to get it right if I can, Scott

[Gary B.]

Re: 68 BB Fan and fan shroud numbers

The metal bracket that secures the shroud to the core support is 3919752 for the early metal shroud. The later fiberglass shroud used 3935570. The lower ring is 3887428, which is a molded plastic piece, for the fiberglass shroud.

The metal shroud did not use a lower extension.

Gary B