tominohio

Hello,
While installing a new fan belt on my 66 327 L79 I noticed the alternator pulley and fan are notched for a keyway. The shaft on my date matching alternator is not machined to accept the same?
What is going on here and how do I correct this??

Bluestripe67

To me it sounds like the alternator on your car is a generic one from some parts place. What is the part number? The "date matching" one you refer to sounds like a correct replacement that the pulley and fan bolt onto the shaft. What is it's part number? Dennis

tominohio

It's Part number 1100693 37A...date is 6D all are dead on for my June build car.
See why the confusion on my end.

dplotkin

Is it possible it was at some point sent out to be rebuilt & had a new rotor installed?


Dan

tominohio

That's very possible. I've had the car since 1976 but the alternator has always charged great. Looks like I need to locate a proper rotor with the shaft machined for a keyway.
Any leads on where this item might be obtained?

Thanks.

dplotkin

I find the rebuilders have access to parts that us end-users cannot always locate. Go talk to the electric rebuilders in your area, all you need is a 10DN rotor, should be easy enough to source.


The 10DN's were good, but they were not 150,000 mile propositions as many are today (I have 230,000 miles on a Bosch in an 18 year old Benz). Its likely it was repaired before you got it.


Dan

tominohio

Thanks Dennis, I'll start looking for 10DN rotor with the machined shaft for the keyway. I have 2003 F-150 with 206,000 and it's still running the original alternator also.

pop23235

No keyway.

leif.anderson93

I believe your issue is with the pulley and fan that you currently have...if I'm reading correctly. The alternator is possibly original to the car but the '66 alternator shaft didn't have a groove for a key way and the original pulley and fan didn't either.

MikeM

That be what I'm thinking too!

tominohio

It's a 327-350 L79 and has the deep grove alt. Pulley 3829387 which is set up for the keyway....so is the fan.

MikeM

You need to talk to an expert.

tominohio

OK....I'll bite. Who would that be.

MikeM

While you're waiting, I'll stick with posts #'s 7, 8, and 9.

PAmotorman

most GM alternators get rebuilt because the back bearing goes out because it is too small

tominohio

Then why is the pulley and fan notched on the L79? What is the point? GM must have felt they wanted to waste a machining process...Not likely.

MikeM

I believe it was spelled out for you in post #9. Did you read it?

Sometimes a replacement part(s) are changed to accommodate other usages than the original design was intended but still carry the original part number.

Before you tear up a perfectly functional alternator, I'd wait on an expert to advise you. I'm certainly not one of them.

tbarb

I have a 1967 #693 alternator in the basement with the fan and 387 pulley which I believe is original and it is exactly as you describe above.

IMO it's correct for your car, there may have been another application for the part which used a keyway.

GUSTO14

This is the GM alternator pulley listed for the L79, it does not have a machined keyway in it.
photo courtesy Paragon Corvette Reproductions

Good luck... GUSTO

tominohio

If you do a search on Ebay you will see this Exact part number in NOS with the keyway. This part was made in both configurations by GM.
At this point I believe based on the opinions of a knowledgeable NCRS judge in my area, I need to source the part # 3829387 without the keyway.
The search begins.