An Infamous "825" Alternator Question

[Jerry Clark]

Good Morning Everybody:

My recently acquired 825 alternator has now become suspect, I have no examples of this alternator either in real life or in my reference library that shows the rear case with any clarity. The Judging Guide refers to "seven raised cooling fins" on the rear case. I must admit that unless the term Fins is subject to interpretation I don't see them. The front case is correctly numbered but I am beginning to wonder if the rear has been replaced. The Vette Vues Fact book shows a picture where the power terminal, (eye connector), appears to be in approximately the 11 o'clock position while the wiring harness plug is in line with the adjuster bolt. If I assemble the cases I have with the harness plug in line with the adjuster bolt, my main power connector, (eye) will fall into the 6 o'clock position, this in turn moves the harness support bracket , ( a formed "L" rolled around the alternator loom ) into a reversed position according to the AIM, which shows it as an upside down "L" . This is all difficult to describe and I hope I have managed to explain it somewhat, I have a couple of JPEG shots that I will happily e mail anyone who may help.

I would like to orient everything correctly but fear I may have the wrong rear case. As always any assistance will be greatly appreciated.

jerry

[Joe L.]

Re: An Infamous "825" Alternator Question

Jerry-----

1969 and, possibly, some 1970 Corvette SI series Delcotron slip ring end(rear) cases have a configuration which is unique to those years. First, there are the "cooling" fins. These are very prominent and are within a more-or-less "flattened diamond" configuration. Second, the alternator rear mounting/grounding lug is drilled and tapped into a boss which is INTERNAL to the case. There is only a very small amount of the boss appearing above the hole----perhaps 1/32" higher than the general plane of the case.

Later SI-series alternators used slip ring end cases which had cooling "slots" or holes, without the raised fins characteristic of the 69 units. Also, the alternator mounting /grounding lug is drilled and tapped into a prominently RAISED boss which juts about 1/2" above the plane of the rear case. This boss usually has small reinforcing ribs surrounding it.

There are also differences in the Delco-Remy script on the rear of the cases. If I recall correctly, the 69 unit has no small, raised rectangle beneath the Delco-Remy script and 1970 model cases do have such a rectangle. Or, it might be the other way around; I just can't recall, at the moment.

In any event, if you have the '825' drive end case, that's the most important and difficult to obtain part. The slip ring end cases, although also rare, were the same for all of the 1969 SI-series Corvette alternators. So, if you don't have one of these, you will be able to locate one of them much more easily than the drive end case. As I've mentioned before, though, all of the 69 drive end cases are configured exactly the same, except for "numbers".

[George Daina]

Jerry, "Mikey" will.......

refund your green if you are not completely satisfied. Maybe that's why you got such a good price?

I would use it, and as Uncle Joe suggests, look for the correct piece at Carlile.

[Rich Mullikin]

Re: An Infamous "825" Alternator Question

Jerry,

I looked for a long time for a correct 833 alternator with a date near my Dec. '69 build date. One, I could never find one with an acceptable date, or they wanted my first male born child as payment. I later found that after September '69 some cars have been seen with '70 alternators. Well, I stumbled across a '70 alternator with an acceptable date for my car and I bought it. That fixed my problem. During my travels I have picked up two '69 alternator backs which I have in my basement. If you are interested in going that route or you want specific configuration information off the backs just email me.

Rich

[Jerry Clark]

Thanks Guys

Thanks to all:

I think I will follow Georges suggestion, hate to think Mike would take advantage thinking I might not "notice".

jer

[Joe Peplinski]

Re: An Infamous "825" Alternator Question

Jerry,

I've looked at my "825" and Joe's response is correct. To give you a better picture of what you should see on the back of the generator, I'll describe it in it's mounted position, looking from the rear/drivers seat.

There are no notable features from 12 o'clock thru 1 o'clock. The gounding lug, is positioned at about 2 o'clock, and it is very short, as described in Joe's response. At 3 o'clock is a small stylized "Delco Remy" in the shape of an oval. Above it and the grounding lug in reasonably large raised letters is another "Delco Remy" that spans a good portion of the width of the case. In the mounted position, this name reads bottom to top, with the bottoms of the letters facing the passenger side of the vehicle. The rectangle mentioned by Joe is not present. From about 5 o'clock to 7 o'clock, there are three horizontal opennings at least 1/4 " wide and 1.5" long stacked up. I can see aluminum heat fins thru the lowest openning. The B+ lug is at 8 o'clock. The regulator harness connector is at 9 o'clock. The diamond shaped heat fin area Jos described stretches from about 9 o'clock to 11 o'clock. The back of the case has some small ridges that define the rough diamond shape of this area. Inside the diamond are 7 horizontal cooling fins of various lengths. They are maybe 1/4" tall and are connected by another small diagonal ridge. There is an approximately 3/8" round hole at 11 o'clock. The rear bearing support in the center has no reinforcing fins.

There, that is the best I can do without a digital camera. To help frame my response, my car is an early (Oct. '68) build L68 with C60 and a properly date coded (for my car) "825" alternator. Good Luck

Joe Peplinski

[Jerry Clark]

Re: An Infamous "825" Alternator Question

Hi Joe:

Great descriptive authoring here and thank you very much, wish I could have done as well.

jer