1970 SB w/AC. Do I have the Correct Fan Clutch & Fan?

[David L.]

Re: 1970 SB w/AC. Do I have the Correct Fan Clutch & Fan?

Clark,

There are 2 alternator fans that are very similar in appearance. GM # 1969448 has a "hook" and GM # 1966990 does NOT. GM # 1969448 was replaced as a service part in May 1969 with GM # 1966990. Apparently noise was the issue with the fan with the "hook".
Does you fan have a "hook"? I'm sure that I still have both fans in my collection. Below is a 2011 photo.

Dave

[Chris D.]

[Clark E.]

Re: 1970 SB w/AC. Do I have the Correct Fan Clutch & Fan?

Guys...My apologies. I incorrectly quoted to wrong fan part # (1966990) in my post and didn't realize it until seeing your responses detailing alternator fan specs. The upside is I now know a lot more about alternator fans.

The issue is the engine fan (Part# 3955182) which is pictured in the AIM drawing as 5, not 7 blades and further described in earlier posts above. Richard Prince detailed on page 101 of the Motorbooks/Workshop Corvette 1968-1982 Restoration Guide on page 101 that (in 1970-72) a "A minority of air-conditioned cars have a five-blade instead of the more commonly seen seven-blade unit. This five-blade fan differs from the one seen in non-air-conditioned cars in that its blades are pitched at a more severe angle." ( He does not say what the angle is.)

I'm trying to build some legitimacy that the five-blade fan in my 1970 is original having owned the car since 1972. Again, sorry for the confusion. Thanks...Clark

[David L.]

Re: 1970 SB w/AC. Do I have the Correct Fan Clutch & Fan?

Clark,

I assume that the engine in your 1970 is original. What is the stamped date on the engine? As far as I know the production of the 1969 Corvettes ended in December 1969, which is quite late. The 1969 Corvette Assembly Manual (UPC C60, Sheet C1) shows a 5 blade fan which the part number listed as "Production Part" which is shown on UPC 6, Sheet A4, as 3888366. Since your fan is stamped "66" it is GM # 3888366. By the Way, the "66" stamping does NOT refer to the last 2 digits of 3888366. The "66" is the middle 2 digits of the Hayes-Albion part number. I know this because I once owned 2 other Hayes-Albion fans each with a 2-digit stamping. I was able to compare the Hayes-Albion part number with the 2 digits stamped on the fan. I have 3 different "Vendor to GM....GM to Vendor" conversion part number books for Chevrolet & GM trucks. Unfortunately I do have one of these part number conversion books for passenger cars, if the even exist.

Dave

[Clark E.]

Re: 1970 SB w/AC. Do I have the Correct Fan Clutch & Fan?

Thanks Dave...The engine is original. The block casting date is early January, 1970 with the car assembly date March 21. The 1970 AIM/UPC C60 sheet C1 indicates the 5 blade fan part # is 3955182 but the drawing mirrors the fan installed on the car's engine.

I appreciate your efforts researching the fan issue. The Forum is full of questions about what happened during the assembly process and unfortunately, available documentation leaves gaps that may never be resolved. It's highly unlikely the fan was replaced during the short period before I purchased the car but I'm not sure how to continue this given the "66" stamped on the fan and your detailed explanation...Clark

[David L.]

Re: 1970 SB w/AC. Do I have the Correct Fan Clutch & Fan?

Clark,

You do have an interesting problem. I assume that your Schwitzner fan-clutch dated 1-17-69 is 7 1/4" diameter making it GM # 3937771 which was the factory installed on 69 & 70 Corvettes (350 w/AC) & BB models. The 3916139, 3916140, and 5329100 fan-clutches listed on UPC 6 (without AC) are all 6" in diameter.

I have nothing else to add. Good Luck.

Dave

[Clark E.]

Re: 1970 SB w/AC. Do I have the Correct Fan Clutch & Fan?

Thanks Dave. Correct. The fan-clutch is 7 1/4".

I appreciate all your research efforts as it at least confirms the fan-clutch is correct. Any idea during engine assembly and installation when the fan was attached to the fan-clutch and subsequently to the water pump?

I'm going to post a new thread asking members with the same or close to build date of C 23 and a 350 w/ air to check their engine to see if they have a similar style fan. Thanks again...Clark

[Clark E.]

Re: 1970 SB w/AC. Do I have the Correct Fan Clutch & Fan?

Thanks Dave. Correct. The fan-clutch is 7 1/4".

I appreciate all your research efforts as it at least confirms the fan-clutch is correct. Any idea during engine assembly and installation when the fan was attached to the fan-clutch and subsequently to the water pump?

I'm going to post a new thread asking members with the same or close to build date of C 23 and a 350 w/ air to check their engine to see if they have a similar style fan. Thanks again...Clark

[David L.]

Re: 1970 SB w/AC. Do I have the Correct Fan Clutch & Fan?

The fan and fan-clutch were installed in St. Louis at the Corvette assembly plant along with other parts that were attached to the engine. The engine was built in Flint.