Fan blade 3931002 - application question

[Jeff S.]

I have a 7-blade, 18" dia, fan with standard 4 holes on 3" b.c. My 1980 edition of the Corvette parts manual shows this p/n as service replacement for '63-'66 with a/c, & for '63-'68 with 327 + a/c. Each blade has the GM p/n "3931002" + the characters "913894K67" stamped on the engine side. One blade has a balance rivet & "A68R" stamped on the radiator side. I don't think any midyears had OEM 7-blade fans, a/c or not.

I'm curious as to the reason for change from 5 to 7 blade configuration with service replacement for a/c cars ... also, does anyone know of if there is any known OEM application for this fan, Corvette or otherwise? The '393' numbering convention seems like a '67-'68 era to me. Thanks in advance.

[William C.]

Re: Fan blade 3931002 - application question

Loads of Chevy, Chevelle, Camaro apps, 1964-1968 some with and some without A/C reference chevy pass car parts book dated 7/75

[Joe L.]

Re: Fan blade 3931002 - application question

I have a 7-blade, 18" dia, fan with standard 4 holes on 3" b.c. My 1980 edition of the Corvette parts manual shows this p/n as service replacement for '63-'66 with a/c, & for '63-'68 with 327 + a/c. Each blade has the GM p/n "3931002" + the characters "913894K67" stamped on the engine side. One blade has a balance rivet & "A68R" stamped on the radiator side. I don't think any midyears had OEM 7-blade fans, a/c or not.

I'm curious as to the reason for change from 5 to 7 blade configuration with service replacement for a/c cars ... also, does anyone know of if there is any known OEM application for this fan, Corvette or otherwise? The '393' numbering convention seems like a '67-'68 era to me. Thanks in advance.

Jeff-----


The 3931002 was SERVICE-only as far as Corvettes are concerned. GM #3931002 was first used for most 1968 passenger car applications with C-60, including full size passenger car, Camaro, Chevelle and Chevy II. It became a SERVICE piece for Corvettes and other pre-1968 passenger cars when the GM #3789562 was discontinued in May, 1972.

[Philip C.]

Re: Fan blade 3931002 - application question

I have a 7-blade, 18" dia, fan with standard 4 holes on 3" b.c. My 1980 edition of the Corvette parts manual shows this p/n as service replacement for '63-'66 with a/c, & for '63-'68 with 327 + a/c. Each blade has the GM p/n "3931002" + the characters "913894K67" stamped on the engine side. One blade has a balance rivet & "A68R" stamped on the radiator side. I don't think any midyears had OEM 7-blade fans, a/c or not.

I'm curious as to the reason for change from 5 to 7 blade configuration with service replacement for a/c cars ... also, does anyone know of if there is any known OEM application for this fan, Corvette or otherwise? The '393' numbering convention seems like a '67-'68 era to me. Thanks in advance.

Hi Jeff 64 and 65 corvette with A/C used the 18 inch 7 blade fan. Phil 8063

[Joe L.]

Re: Fan blade 3931002 - application question

Hi Jeff 64 and 65 corvette with A/C used the 18 inch 7 blade fan. Phil 8063

Phil------


Yes, they did. However, they didn't use the 3931002. They used the GM #3853943. The latter was discontinued in August, 1977 and was also replaced by the 3931002.

[Philip C.]

Re: Fan blade 3931002 - application question

Phil------


Yes, they did. However, they didn't use the 3931002. They used the GM #3853943. The latter was discontinued in August, 1977 and was also replaced by the 3931002.

Hi Joe, I was answering Jeffs question (I don't think any midyears had OEM 7-blade fans, a/c or not.) I got no idea what a 3931002 fan is! Thanks Phil 8063

[Joe L.]

Re: Fan blade 3931002 - application question

Hi Joe, I was answering Jeffs question (I don't think any midyears had OEM 7-blade fans, a/c or not.) I got no idea what a 3931002 fan is! Thanks Phil 8063

Phil------


The 3931002 was an 18" OD, 7 blade fan. Just how it differed from the original 3853943 which was one of the fan blade assemblies it replaced I do not know. A lot of these 3931002 seem to show up on Corvettes, but I don't think that any Corvette was originally equipped with one. Certainly, no Corvette prior to 1968 was ever equipped with one.

[Wayne M.]

Re: Fan blade 3931002 - application question

Phil------


Yes, they did. However, they didn't use the 3931002. They used the GM #3853943. The latter was discontinued in August, 1977 and was also replaced by the 3931002.

Joe and others:

There's a service '943' , new in-the-GM-box, on eBay right now; about $150 with 11 hours to go. Looks identical in blade shape to the original production. It has flat head rivets, which may or may not be TFP depending on the '64 or '65 year.

[David L.]

Re: Fan blade 3931002 - application question

Phil------


The 3931002 was an 18" OD, 7 blade fan. Just how it differed from the original 3853943 which was one of the fan blade assemblies it replaced I do not know. A lot of these 3931002 seem to show up on Corvettes, but I don't think that any Corvette was originally equipped with one. Certainly, no Corvette prior to 1968 was ever equipped with one.

Joe,
The 3931002 fan (2" pitch, 3.00 BC) has aluminum blades with curved tips and is a "one year wonder" used in production only in the model year 1968 on Chevrolet cars with AC, NOT on HP engines or Corvettte engines. It is identical to the 3937779 (2' pitch, 3.25" BC) fan used on "early" 69 Z28's and other Chevrolets w/AC EXCEPT for the bolt circle diameter and very similar to the "late" 69 Z28 fan (3947772, 2.25" pitch, 3.25" BC).
The 3931002 fan was also used as a service replacement for the Corvette & Chevrolet fans.
The 3853942 fan has steel blades.
Dave