Switching Alternator Parts on a 67 w/AC

[Kirk McHugh]

I am going to replace the alternator on my 1967 327/300HP with AC with a properly numbered unit. I've read up on doing it (Service Manual) and talked to some friends and it seems like it shouldn't be too hard. Here is my question though.

I bought a new properly numbered unit for an AC car. The front part of the alternator is correctly numbered for my car, but the back half of the unit seems like a later unit in that it doesn't contain the hole for the wire harness clip. The current unit on the car is not numbered correctly on the front but appears to have the proper configured back half. Question is this - can I switch the halves around?? I have already taken the new unit apart and encounter the two springs and bars (sorry I have no idea what they are really called) coming out. I figured out how to get them back in correctly and held in place, so is it as simple as putting the properly numbered front on the properly configured back???

Someone let me know if I'm missing something. Thanks.

[Donald Milone (8060)]

Re: Switching Alternator Parts on a 67 w/AC

Kirk, Don, again. This very subject was recently discussed (last week?) on this board. Just go into the Archives and search for "alternator" or "alternator clocking" for the most recent posts. Those bar thingies are the carbon brushes and their tension springs and yes,they will fly out of the housing as soon as you separate the halves. I would think that if you have the correct AC alternator (part#, amp rating, date code), you "may" be able to swap the rear half off your current unit. I'm not sure, electrically. Are diodes, rectifier, etc. the same? Maybe one of our resident experts can jump in on this question.
Don

[Gerard Fuccillo (42179)]

Re: Switching Alternator Parts on a 67 w/AC

Kirk,

If the wiring harness hole is the only difference, I think it is a matter of which rear case with diodes and with rotor/stator work the best. I think I'd get them both load tested and test the diodes of each (See your Chassis and Overhaul Manuals). Use the rear case and rotor/stator of the one that works the best. I think you could always drill the harness hole (again if that's the only difference). If you are going to switch rotors, switch both rotor and stator as a matched pair.

If both are in equal load codition and diodes are good, then consider best match in finish.

While you are in there, check the condition of the brushes (springs and bars), replace if necessary, carefully clean off the armature. Also check your bearings, replace if necessary.

When you put it back together, get the clocking correct. It is an easy mistake to make, I know.

Jerry Fuccillo
#42179

[Jack Humphrey (17100)]

Diodes were the same...

regardless of the alternator's specific PN and current rating. That's one smart move Delco Remy made to reduce PN proliferation! The only difference is going to be specific diode vendor ID & date coding...

[Gerard Fuccillo (42179)]

Toothpick trick

to reset the brushes on reassembly. But the clockung is wrong for my 67 base engine.

The alternator in the picture is my 37 amp original, with a generic 60 amp rotor stator. Works just great.

Jerry Fuccillo
#42179

[Kirk McHugh]

Re: Toothpick trick

Now you guys are scaring me. So someone tell me in simple, plain language what I need to do. I do not understand what "clocking" means. The unit I bought was suppose to just replace the one I had, or would I have still needed to "clock" it once installed? I'm sorry to be so "stupid" about this, but again maybe this is something I should leave to a professional?? If not, how do I go about doing the things you suggested? Thanks.

[Kirk McHugh]

Re: Switching Alternator Parts on a 67 w/AC

I assume "rotor" means the front half of the alternator, what exactly is the "stator"? The back half or some portion of the back half?

[Verle Randolph (14764)]

Re: Toothpick trick

Kirk,

The alternator case is two parts, front and back. Two small bolt holes visible top left and top right on the back in Gerard's picture (there are four altogether) would have bolts that hold the two halves together.

What they mean by clocking is the position the two halves are put together.
In his picture the alternator bracket boss is at the top of the front half. Note the position of the place on the back where the wires plug in, just above the center.

If you removed the four bolts and turned the back half 90 degrees clockwise (without pulling the two halves apart) and put the bolts back in you would have changed the "clocking" of the case.

Look at or get pictures of known original alternators appropriate for your car to see what your clocking would be.

Verle

[Verle Randolph (14764)]

Re: Switching Alternator Parts on a 67 w/AC

Kirk,

The rotor is the part inside the alternator that turns (rotates). The pulley and fan are on the front of the rotor shaft.

The stator are fixed (do not move) to the inside of the case.

Verle

[Terry McManmon (3966)]

Re: Switching Alternator Parts on a 67 w/AC

I would think the service manual has an exploded view of the alternator with parts identified. A picture is always worth a lot more than words, even my words, but to simplify:
Rotor = the internal part that rotates
Stator = the internal part that does not rotate. One can see part of the stator, the dark band in the middle, between the front and back aluminum pieces.
Front case = the aluminum part the adjusting bolt screws into with the stamped numbers on it. This part holds the front bearing.
Rear case = the aluminum part with the diodes, rectifier bridge, brush holder, and rear bearing in it. This part is toward the rear of the car as the alternator is installed.

Clocking refers to the relationship of the front and rear cases. They are held together with four screws and can be assembled in any of four positions relative to each other. Only one of those positions is correct for a given engine/accessory configuration. I don’t think the service manual will tell you about the clocking, or how to do it – but it will tell you about the toothpick trick.

[Kirk McHugh]

Re: Switching Alternator Parts on a 67 w/AC

Makes sense now. I figure out the toothpick trick on my own - not as dumb as I read - at least sometimes. The clocking I can get from the unit that is currently on the car - I just need to set the new one up in the identical position. Since the "new" old unit was reconditioned and tested and the current unit is on the car and running fine (it just isn't the right serial and date), I think I should be fine switching them around. Does that seem correct to everyone else?

[Terry McManmon (3966)]

Re: Switching Alternator Parts on a 67 w/AC

Kirk -- so long as all parts are functioning and in good shape -- there should be no problem switching the rear cases. That said sometimes a slight difference in external finish will become noticeable once part of the case is changed. This is, as someone suggested, a good time to replace the brushes if they are getting short -- which shouldn't be the case for a newly rebuilt unit.

We used to teach how to troubleshoot and rebuild alternators and starters in automotive electrical classes. Now days so few units are field rebuildable, and often internal parts are not available in the field, we no longer teach students this valuable skill.

Good luck with your project.

[Terry McManmon (3966)]

Holding the brushes for rear case install

I forgot to mention -- some folks use a straightened paperclip instead of a toothpick. NOT a good idea. Imagine what will happen if you forget the paperclip and power up the alternator with the paper clip in there. The non-conducting wood toothpick, or the plastic tube that comes with a new Delco brush holder set, is a far better idea.

[Jeffrey Salz (13182)]

Re: Switching Alternator Parts on a 67 w/AC

Wouldn't it be a lot easier to simply switch the FRONT half of the case form the "new" unit to the one already on the car? This does not involve removing any internal parts or brushes, springs etc. Am I missing something here? Just a thought.
Jeff

[Gerard Fuccillo (42179)]

Take a look at this thread

Kirk,

https://www.ncrs.org/forum/archive23.cgi?review=198571

You'll see pictures of all the various alternator parts here. You'll also see the difference in clocking between the original (on the left) and a replacement in one of the pictures.

It's really a pretty easy job to overhaul one of these alternators. Follow the Service and Overhaul Manual.

Jerry Fuccillo
#42179