1969 Alternator

[Steve M.]

I have finally found a 1100859 alternator for my 1969 350/350 Corvette. The car does not have power steering or air conditioner. Unfortunately it does not ahve the fan or pulley. In talking with an altaernator shop they indicated that the correct pulley was 3 5/8" 3829387AI. This does not match the NCRS Technical Manual. Thanks in advance for any information anyone can provide.
Thanks,
Steve

[Joe L.]

Re: 1969 Alternator

Steve-----

There MAY be a problem with the JG on this one. However, I don't think that the 3929387 pulley is correct in any case.

I show that 1969 with L-46 and without C-60, N-40, or K-66 originally used pulley GM #1970831. This is a 1 groove, machined steel pulley of 3-3/16" OD. It was discontinued from SERVICE in November, 1984 and replaced by GM #3844100. This is an almost identically configured pulley which is 3-7/32" OD (i.e. 1/32" larger in OD).

I show that the fan used for the 1969 L-46 application was GM #800594. However, I'm not 100% sure that this fan was actually used. It may have been another very similar fan.

I have the ability to further check on this issue, though. I have a friend who is the original owner of his October, 1968-built 1969 L-46. I know that it still has the original alternator, pulley, and fan on it. In fact, the car's been sitting in his garage for at least the last 25 years. I'll stop by and look at it. Of course, this won't tell us how EVERY alternator, fan, and pulley used on a 1969 L-46 was actually configured, but it will tell us, for sure, how ONE was configured.

[Joe L.]

Re: 1969 Alternator

Steve------

Well, it turns out that the JG was more correct than other GM information that I referred to earlier. However, these alternator pullies are one of the more vexing subjects regarding old Corvettes. I've always considered the GM spec information "sketchy" and unreliable. This case just proves my point that much more.

Anyway, I've had a chance to check out the alternator on my friend's car. As I mentioned, his car is an original owner, 1969 L-46 and I am 100% certain the alternator has never been changed. His car does have power steering (I didn't think that it did), but that makes no difference as far as alternator pullies go for this application.

As it turns out, his car has the exact same alternator pulley and fan configuration as my original owner 300/350. It has a GM #1949357 pulley with a GM #800594 fan. The GM #1949357 pulley is a stamped steel pulley which is zinc plated. It has the number "7" stamped on the side of the pulley. It is 2-7/8" OD which is contrary to the GM spec of 2-3/8" OD. However, this is another area of alternator pullies where "reality" is often at odds with GM spec. Apparently, GM used some convention other than the major outside diameter of the pulley to describe its OD. Why, I do not know.

Also, the GM #1100859 alternator, the same one as originally used on my car and, indeed, the correct one for your L-46 without C-60 or K-66, was originally supplied to PRODUCTION with the pulley already installed. Some alternators were supplied to PRODUCTION with the pulley/fan already installed; some did not have the pulley/fan installed and they were, therefore, installed at the assembly plant. This is one of the reasons for all the different alternator part numbers. Considering the with or without pulley/fan, 4 possible clocking positions, and 3 or more amp ratings, a lot of possible different configurations (and, consequently, part numbers) occurred.

I am attaching a photo of the alternator pulley/fan configuration on his car and will follow with several other photos. You will note in the photo below that the pulley is stamped with the "7". This represents the last digit of the GM #1949357 part number. You will also note that the fan is zinc or cadmium plated, not black.

[Joe L.]

Photo Addendum #1

This photo shows the original fan blade that was installed on my 1969 with GM #1100859 alternator. Note that it is identical to the fan on the original L-46 shown in the previous photo. GM SAYS, as I mentioned in my previous post, that this is a GM #800594 fan blade. I don't think so. I think that this fan blade and the one installed on my friend's original alternator (pictured previously) are both GM #1966990 fan blades. GM says that the 1966990 was never used on a Corvette but I think otherwise. The 1966990 is an 11 blade fan with asymmetric blade arrangement. The GM #800594 is a 10 blade fan with a more subtle asymmetric blade arrangement.

The GM #800594 fan is still available from GM to this very day.

[Joe L.]

Photo Addendum #2

Below find a photo of the original pulley from my GM #1100859 alternator as originally installed on my 1969 300/350. Note that it is identical to the one on my friend's original 1969 L-46. Note that it includes the stamped "7".

His car did not use the GM #1100859 alternator, though. Since his car is equipped with K-66, he has a 61 amp alternator installed. Curiously, it is a GM #1100882 and it's dated "8K25".

[Joe L.]

Photo Addendum #3

This is a photo of a GM #1949356 pulley. Note that it is stamped "6". This is the pulley that the JG says was used for most 1969 small block applications. It may very well have been used alternately with the 1949357 for some applications. It is a very similar pulley except that its actual OD is 2-5/8".

The GM #1949357 pulley was discontinued from SERVICE in November, 1966 and replaced by the GM #1949355. However, the 1949357 was used in PRODUCTION after that time as clearly evidenced by the fact that it was originally used on both my late-build 1969 as well as my friend's early build 1969.

The GM #1949355 was discontinued from SERVICE in January, 1982 and replaced by the GM #1949356. The 1949355 was originally used for the alternator pulley for many C-60 applications.

[Joe L.]

Photo Addendum #4

Below is a photos of, left to right,

1) An NOS GM #1966990 alternator fan blade;

2) The original fan blade from my 1969 GM #1100859 alternator (identical with the fan blade on my friend's L-46);

3) A new GM #800594 fan blade.

Note that the 1966990 and the original fan blade are nearly identical. The only difference is the size of the "cutout" on the edge of the largest blade. That could well be due to tooling differences in different sets of tooling OR a small change made at some point to the spec of the 1966990 blade assembly.

Note also that the GM #800594 is a completely different fan with 10 blades, not 11. It's configured much differently than the others.