Installed this new Powermaster part PWM-7102 100 amp alternator and hooked it up like the old alternator was wired. This is in a 72 Cutlas Supreme. Externally regulated with a wiring harness American Autowire made for me to accommodate an HEI distributor. The new alternator made a screeching noise when it wasn't under much load. When I turned electrical components on it stopped squealing. Also I thought the unit was hotter to the touch after running less than 3 minutes than I thought it should be. Does this new alternator need to be grounded? Anybody see something improper in these pics?




The old alternator did not have a ground coming off the casing. It's the Powermaster PWM-7102 unit that Summit sells.

 

pic of old alternator

 

Something peculiar regarding that 7102 Alternator? PowerMaster does not list that alternator as fitting a 1972 Oldsmobile Cutlass. The model year applications (listed by PowerMaster) demonstrate 1963-1971 (Catalog page 128, Model 7102).
Additionally, the same alternator is listed in the same catalog (page 66) as a 70A alternator (Model 7102). It is listed as the 10DN family, but it (again) is not listed as applicable for the 1972 Cutlass Model year. I'm only the messenger - I don't know why.
Summit also lists the 7102 as not applicable for the 1972 Cutlass Model year. I'd call PowerMaster.
http://www.powermastermotorsports.com/catalog.html



Powermaster Catalog page 128

 

Powermaster Catalog Page 66

 

The alternator case is the ground connection. If the mount area of the alternator is not connected to bare metal, (painted block and adjustment bracket) you may want to add a ground wire. The squeal may be from having the wrong pulley V groove width. I can't be sure from the pics, but it looks like the belt is riding too high in the groove. The belt should not be riding over the edge of the pulley. Maybe it is the wrong belt. If the belt width is correct you may want to change the pulley.

 

As Stellar said make sure you're using the right pulley. It's a good idea to take the pulley off of your old alternator and install it on the new one. Also like Norm indicated, run a chassis ground from the alternator case to your negative battery terminal. It shouldn't be listed as optional. Good grounding and bonding is essential. If done improperly, you have an OE wiring harness that melts down like the harness in my 86 Ford F250.

 

Once again, aftermarket catalogs are incorrect. Olds did NOT use an SI-style alternator on the 1972 Cutlass line. All of them came with 10DN alternators and external regulators. While the OP's new alternator does not have the correct 1972-only case, it is functionally correct for his application.

 

The alt you removed looks original and pretty cool looking too; why not send it off for a rebuild, or have it rebuilt locally? You can't go wrong wtih original.

 

I'm the messenger not the editor of the PowerMaster web pages. NOTE: Their webpage lists this alternator as a 10DN. I'm unclear why we're discussing an SI-style. Was there a post I missed?

 

The chart you included in Post #3 says that a 1972 uses a 10SI, which is incorrect.

 

Gotchya. I was trying to review all of their alternators last night to determine if his (7102) was an SI. It is not listed as an SI, it is correctly listed as a 10DN. But, I should have paid more careful attention to detail in the lines above which, as you stated is incorrect and lists the 1972 model year as a 10SI. Thanks for pointing that out.

 

Thanks everybody! I was hoping it was possibly old belt/new pulley issues. I'll check that out first and clean up and remove any paint on painted metal contact points. Probably will have to swap old pulley if GM changed belt spec between model years I guess. Good news is my volt meter was basically reading high 12's to 14 volts with just a slight rev increase. I have a solid state voltage regulator installed as well which helped with voltage swings with the old alternator. I saw another thread where that small 3/16" threaded stud (not being used in pic) on the backside of the alternator is an accessory AC feed. Can anybody confirm that? Thanks again guys for the help. This site saves my butt every time. Good to read things like '72 only case'. That stuff is truly important, thanks Joe, I had no idea but now I know why placement of the wire connects wasn't quite the same.

 

That other threaded stud is grounded. It is not a feed for anything.

 

I think the pulley on the 7102 has a 3/8 inch wide groove. That is a pretty narrow belt.

 

I found out Powermaster makes a pulley that better matches the other original pulleys on my '72 and it was available through Summit. It is a 3/8" x 2.33 OD v-groove and stock belt sinks lower into the V. Part is Powermaster 111 v-belt alternator pulley. Easiest fix and it looks pretty good. All squealing noise is gone now. I guess Powermaster supplies with that 3/8" shallow V pulley because it covers more applications but it was a curveball for me. By the way that original case I had spray painted with Eastwoods Alumablast paint and it did look real good when it was done.