66 Alternator fan-pulley 3843342 - 2 versions

[David L.]

I have two different versions of the fan-pulley used on 1966 Corvettes w/300 HP engine and without AC.
Both fan-pulleys are dimensionally the same and I assume that they were made by two different companies.

In the photo the fan-pulley on the left side is stamped "3843342 AJ" and has 6 rectangular indentations forming a circle with a radius of about 1 3/16" on the front face. The back side has a single number "1" which I believe represents the month of January as this fan-pulley was removed from a 1100693 37A alternator dated "6 B 11" (Feb. 11, 1966).

The fan-pulley on the right side does NOT have a stamped GM part number but does have 6 circular indentations forming a circle with a radius of about 1 3/8" on the front face. The back side has a larger number "2" (February) as this fan-pulley was removed from a 1100693 37A alternator dated "5 B 26" (Feb. 26, 1965) that came from a 1965 Chevrolet w/283 engine.

The 3843342 fan-pulleys were used on 1965-1966 Chevrolets, Chevelles, and Novas as well as 1966 Corvettes with base engines and without AC.

My two questions to those who still have there original alternators on their 1966 Corvettes w/300 HP engines and without AC are this:

1. Is you 11-blade fan-pulley stamped "3843342 AJ"?

2. How does the number (# 1 to #12) on the back side of the fan-pulley compare to the date code on your 1100693 alternator?

[Timothy B.]

Re: 66 Alternator fan-pulley 3843342 - 2 versions

David,

I have the same two pullies exactly as you state. Mine have a 5 stamped into the back so both pullies are from May 1965 or 66.

[Jim C.]

Re: 66 Alternator fan-pulley 3843342 - 2 versions

Okay David,

Let me start by saying that I am a "numbers" fanatic for sure!!! I'm ALWAYS interested in finding new numbers on my car. When I saw your post, I had to take a look at my own car. I have a VERY late base model 1966 with a 327/300, and no AC. I'm fairly certain that my alternator is original to my car.

So, here's what I already knew. My alternator is stamped with part number 1100693 37A, and is dated 6F29 (June 29, 1966).

Here's what I discovered. My alternator fan is stamped with part number 3843342AJ. Although I never noticed it before, that stamp just so happened to be positioned right on top and was very easy to read. No doubt about that number. It was very clear.

As for the date stamp on back, that was significantly more difficult to read. First off, I had to find it, and then I had to figure out how to read it. Certainly not an easy task with the alternator on the car. There's not a lot of room between the anternator and the alternator fan. Anyway, I was able to see a small "dent" on one of the blades from the front of the fan, so I figured that was the stamp. Unfortunately, even with a small mirror and a flashlight I couldn't make out the stamp. I could see it and feel it with my finger, but I just couldn't read it. Don't worry, I didn't give up. I went out in my shop and found my Silly Putty and a popsicle stick. I pressed the Silly Putty behind the fan blade with the popsicle stick and then carefully peeled it off the back of the blade to look at the impression. I took the Silly Putty out into the sun light and observed it under a magnifying glass. Without a doubt it was a "6." No doubt about it. 6 = June, right? I think that matches your theory.

I hope this information is helpful to you. I enjoyed it because I found two more numbers on my car that I did not know existed. I look forward to reading other responses.

Jim C.

[David L.]

Re: 66 Alternator fan-pulley 3843342 - 2 versions

Over the last 30 years I have collected as many as 25 or 30 alternators from junk yard Chevrolets as well as at swap meets. When I removed the fan-pulleys or fans & pulleys from the alternators I sometimes, but not always, tagged them. Several years ago when I was looking for a particular fan-pulley I noticed the correlation between the date code of the alternator and the number stamped on the back side of the fan part. I am confident that this number is the month that the fan-pulley was made. This number seems to always be stamped on one of the larger of the 11 blades.

The other issue is to determine whether or not the factory installed fan-pulleys on the 1966 Corvettes (w/base engine and wo/AC) always had the stamped "3843342 AJ" part number. The "3843342 AJ" stamped fan-pulleys have the 6 RECTANGULAR shaped indentations on the face of the pulley.

I have a few 3843342 fan-pulleys WITHOUT the part number stamping but they all came from 1100693 alternators with 1965 date codes. They all have the 6 CIRCULAR shaped indentations on the face of the pulley and a number of the back side for the month but this number is much larger in size.

My question:
Is this a fan-pulley design change from 1965 to 1966 or were the two different but dimensionally the same fan-pulleys made by different manufacturers?

Dave

[Jim C.]

Re: 66 Alternator fan-pulley 3843342 - 2 versions

Dave,

I can't answer your last question, but I can confirm that my date stamp was on the back side of one of the larger fan blades. Nice job connecting the stamp on the back of the blade to the alternator date stamp. Pretty cool stuff!! Those little things just add more authenticity and originality to the car. Thanks for posting your findings.

Jim C.

[William G.]

Re: 66 Alternator fan-pulley 3843342 - 2 versions

Greetings,

My 1966 300 HP non AC Bowtie car was built on the 19th of April and has the original alternator with an early April date. The fan/pulley carries the 3843342 AJ number with a "3" (March) stamped on the back of one of the blades. I'm not sure about the 1 3/16" radius arc or circle formed by circular or rectangular impressions (?). I'll have to look for that in more detail--I have noticed rectangular impressions on the pulley which seem to go all around the pulley face rather than just six impressions (something to do with the stamping die which made the pulley I would guess).

Bill

[David L.]

Re: 66 Alternator fan-pulley 3843342 - 2 versions

Bill,

I assume your "3843342 AJ" fan-pulley looks exactly like the one shown in my photo in my first post. The "3843342 AJ" fan-pulley has 6 rectangular indentations which if you drew a circle thru all of them would have a diameter measuring about 1 3/16" (see photo).

The 3843342 fan-pulley which does not have a stamped part number has 6 circular indentations which if you drew a circle thru all of them would have a diameter of measuring about 1 3/8" (see photo).

Dave

[William G.]

Re: 66 Alternator fan-pulley 3843342 - 2 versions

Dave,
No............not really the same. But, then my pulley/fan is still attached to the alternator and what I'm therefore seeing is a large diameter spacer or washer which hides that part of the pulley you show in your photos with the stamped rect. or circles.

Bill