71 5 blade fan

[Romeo]

Hi all

I'm looking for a 5 blade fan and clutch for my '71 non AC vette.

I was told the part number is 3991420, my AIM shows a slightly different number.

I'm looking for any help as to what the correct number is and where I can find these parts. I came across these parts...are they correct?

Thanks

[Jack H.]

Open...

your copy of the AIM to UPC 6, Sheet A3. Note Item 14 is called out as GM 3888366 and there are three different, yet equal, supplier PN's for Item 13 (the fan clutch) listed as 3916139, 3916140 and 5329100. The first two are from outside suppliers (Eaton coil style, Schwitzer bar style) while the third is a Delco Remy 'clone' of the Eaton coil clutch.

I believe ALL of these are long ago GM discontinued/superceeded and unless you're looking for a functional service replacement (expect it to take minor deduction during judging), you'll have to KNOW the correct visual characteristics of the parts and find used originals on eBay, at swap meets, in Driveline ads, Etc.

The correct/original PN's really aren't much help as neither the base 5-blade fan or the first two versions of the fan clutch have PN's on them...

[Romeo]

Re: Open...

Thanks Jack

the one in the picture doesn't have a PN, but says

"THERMATIC FAN DRIVE"

and

"PATENTED/PATENTED CANADA 1961
OTHER PATENTS PENDING"

any idea if this could be from a '71?

[Jack H.]

Re: Open...

The one pictured is generically correct for the style of Schwitzer that was used in that era, plus the fan blade has the proper style of rivet heads (flat vs. mushroomed). BUT, you can't tell from a simple picture if the fan clutch is actually correct or not. Why?

Schwitzer made several versions of the 7-inch, bar style clutch with the differences lying in: (a) the length of the shaft, (b) the geometry of the mounting hub and its water pump attaching bolt holes, as well as (c) the height of the cooling fins surrounding the bi-metal actuator on the face of the clutch.

[Joe L.]

Re: Open...

Romeo-----

Actually, I don't think that the GM #3888366 fan was really used on 1971 Corvettes. If it was, at all, I think the usage was limited to very early cars.

What is the CASTING # of the waterpump on the car now and do you believe it to be the original pump? Second, and most important, what is the part number of the waterpump pulley on the car? This number will be stamped into the pulley.

[Romeo Sinopoli]

UPDATE

Thanks Guys, I followed along in the AIM and see the same PN mentioned above.

About my vette, I've had it 4 yrs and was told I should get it judged after correcting the obvious. I'll spend the winter searching for correct parts..fan, alternator, etc. I'm in Toronto, so only a few more weeks of driving. I'm attaching a current picture of my setup for you experts to critique. I'm buy the fan/clutch in the prevoius picture because the cost is only $22, who knows sounds like a good deal if it turns out to be correct. I'll post more info. once I have it. My fan now is chrome, the previous guy liked to dress it up.

[Romeo Sinopoli]

Re: UPDATE *NM*

[Patrick H.]

Re: UPDATE

Romeo,

I note the fan has a "W" on it.
It may be the original fan, but he had it chromed. Any chance you found any other numbers on it?

Also, look closely at the mounting edge of the fan clutch, where it mounts to the water pump pulley. Is there a date stamped on the edge? The 1970 I'm working on right now has 5 5 70 stamped on the edge in plain sight, and the clutch appears exactly like the one you show.

Let us know what you find.

Patrick

[Joe L.]

Re: UPDATE

Romeo-----

From what I can see of it the waterpump looks like a GM #3991399 casting. That means that the waterpump pulley is almost certainly a GM #3991423. That, in turn, means that the fan clutch should be a GM #3991426 and the fan a GM #3991420.

From what I can see of them, the fan clutch and fan on the car now are the above-referenced pieces with the exception of the finish on the fan.