65 alternator fan/pulley

[Jim D.]

I've found a lot of conflicting info. regarding this item for a 1965 non-A/C L75. The TIMJG states it's 2 separate pieces, all the parts suplliers sell them as 2 pieces BUT, I did a search here and found pictures of original 63-64 and 66 parts that are 1 piece. Does anyone have the definitive answer on what it should be?????

Jim

[David L.]

Re: 65 alternator fan/pulley

Jim,

According to my 1965 Chevrolet Parts Catalog (May 1965) the pulley listed for the 65 Corvette (exc. C.A.C., Sp. H/Per., F.I.) is GM # 3871241 in Gr. 2.274. The description is 2 53/64" O.D. w/3/8" groove. I have many alternator pulleys in my "collection" but I do not believe that I have this one but I might. I suspect that the 3871241 pulley is the solid steel type (as opposed to the stamped steel type) but I am only guessing.

The fan is GM # 3843346. Enclosed are 2 photos (front & back sides) of a used 3843346 11-blade fan. I also have a NOS 3843346 fan. The 3843346 fan was discontinued in June 1971 and replaced with GM # 800594.
The 3843346 fan was also used with the 1965 Corvettes w/L76 and L78 options.

Dave

[Wayne M.]

Re: 65 alternator fan/pulley

I've found a lot of conflicting info. regarding this item for a 1965 non-A/C L75. The TIMJG states it's 2 separate pieces, all the parts suplliers sell them as 2 pieces BUT, I did a search here and found pictures of original 63-64 and 66 parts that are 1 piece. Does anyone have the definitive answer on what it should be?????

I always thought the issue, with respect to 1965, is whether the air conditioned base engine and L75 used a separate pulley/fan. The judging guide says yes, the AIM says no (integral fan/pulley part # 3875968, UPC C60, sheet C2, item 9) [pic below, on left].

[Jim D.]

Re: 65 alternator fan/pulley

Thank you gentlemen. That makes it perfectly clear.

Jim

[Wayne M.]

Re: 65 alternator fan/pulley

Jim,

According to my 1965 Chevrolet Parts Catalog (May 1965) the pulley listed for the 65 Corvette (exc. C.A.C., Sp. H/Per., F.I.) is GM # 3871241 in Gr. 2.274. The description is 2 53/64" O.D. w/3/8" groove. I have many alternator pulleys in my "collection" but I do not believe that I have this one but I might. I suspect that the 3871241 pulley is the solid steel type (as opposed to the stamped steel type) but I am only guessing. ..

Dave -- do you think this one might be 3871241 ? Solid, measures (caliper 2.813" dia.[ie. 1/64th" less than parts catalog]. Got it off a junkyard '65 Belair 283/195hp.

[David L.]

Re: 65 alternator fan/pulley

Dave -- do you think this one might be 3871241 ? Solid, measures (caliper 2.813" dia.[ie. 1/64th" less than parts catalog]. Got it off a junkyard '65 Belair 283/195hp.

Wayne,

The 65 Chev. 283 used a one-piece fan-pulley, GM # 3843342 (O.D. of pulley measures about 2.82") as shown in the 65 Chev. AIM and my 1965 parts catalogs. Was the alternator an original? Did the alternator date code match up with other date codes on the 65 Chev.?

The 64 Corvette (250 & 300 HP) used pulley # 3844101 (2 13/16" O.D. or 2.813") which was replaced by the 65 Corvette 3871241 pulley 2 53/64" or 2.828") on 9/23/64 as per revision record in 1965 AIM.

I believe that your pulley is probably GM # 3844101.

I firmly believe that the 3871241 pulley was used on the 1965 Corvette L75 (without AC). I did some research on all 1965 Corvette alternator pulleys in January 1990 as shown in the photos below.

Based on my research the 3875968 fan-pulley only was used on 65-66 Chevrolets, Corvettes and Chevrolet trucks with A.C. The 3875968 fan-pulley was used on 1965 Corvettes w/L75 & C60.

Dave

[Jim D.]

Re: 65 alternator fan/pulley

Great info. Dave. Thanks for posting it.

Jim

P.S. After checking mine, it appears to be the original set-up. I knew the alt. was original but seeing the pictures of 1 piece units with stamped steel pulleys had me concerned because mine was different. Thanks again for the info.

[David L.]

Re: 65 alternator fan/pulley

Jim,

Pictured from left to right are 3 "solid type" alternator pulleys in my "collection".
On left is GM # 1958095, 3.00" measured O.D. (1963 part catalog O.D. = 2 7/8"), 1.00" measured thickness, "V" groove is offset.
In middle is an unknown pulley, 2.84" measured O.D., 0.75" measured thickness, centered "V" groove.
On right is an unknown pulley (possibly GM # 3850155???), 2.53" measured O.D., 0.87" measured thickness, "V" groove is offset.

I assume that your pulley is GM # 3871241, measuring 2 53/64" or 2.83" in diameter. Is the "V" groove offset or is it centered? If the "V" groove is offset is the thickness about 1" or 7/8" thick?

Dave

[Jim D.]

Re: 65 alternator fan/pulley

Dave, Mine doesn't match any of those exactly. It is 2.825 O.D, 3/8th offset groove and is 1" thick. The date on the alt. matches perfectly and this is a 1 owner car. Your thoughts?

[David L.]

Re: 65 alternator fan/pulley

[quote=Jim Durham (8797);552605]Dave, Mine doesn't match any of those exactly. It is 2.825 O.D, 3/8th offset groove and is 1" thick. The date on the alt. matches perfectly and this is a 1 owner car. Your thoughts? quote]

Jim,

I would say that the pulley is GM # 3871241, 2 53/64" O.D. (2.83") and is correct for your car.
It makes sense to me that your pulley is 1" thick with a "V" groove offset similar to the 63 Corvette pulley (GM # 1958095) as shown in my photo in my previous post. The offset is necessary so that all the pulleys (alt, w/p, and c/s) line up in the same plane.

The 63-65 Corvettes (base eng., etc.) used the same w/p pulley (3790356) and the same c/s pulley (3744043) so since the 65 alternator pulley (2.83" O.D.) was slightly smaller it would a require a slightly shorter fan belt (GM # 3847701, 3/8" by 55 1/4" long). The 63 Corvette with the 3" O.D. alternator pulley used fan belt # 3759221, 3/8" by 55 1/2" long.

Dave

[Joe L.]

Re: 65 alternator fan/pulley

Dave, Mine doesn't match any of those exactly. It is 2.825 O.D, 3/8th offset groove and is 1" thick. The date on the alt. matches perfectly and this is a 1 owner car. Your thoughts?

Jim------


My opinion is that this is the original pulley and fan. As far as the OD discrepancy is concerned, I have found that the P&A specified dimensions of pullies often slightly differs from the measured OD of known examples of said pullies.

[Jim D.]

Re: 65 alternator fan/pulley

Thanks for your replies Dave, Wayne & Joe. It all makes perfect sense now.

Jim