Mid 9, Upgrading Alternators, Regulator compatibility?

[74cookiecutter]

Calling all Electrical specialist!
I have a 55amp Marchal Alternator that is currently not working but the matching external regulator is. The replacement Alt I received (long story) is the 70amp model SEV Marchal.
The 70amp is about a 1/4" deeper which will work well with my belt and pulley setup but I'm concerned that the original stock Regulator will not work properly.

Anyone had this situation and know if the 70amp Alt is compatible with my current Regulator?

Here is my stock Alt. and Reg.

[Early_S_Man]

Yes, that regulator with the 03 85 date code should work just fine with the 70 Amp alternator.

The fan housing is supposed to be machined 9.3 mm deeper for the 980 Watt 70 Amp alternator ... per the factory service manual.

[74cookiecutter]

Thanks for the data. What is the significance of the 03-85 date? when were the 70a Marchals adopted?
As for the 9.3mm depth. I purchased the Fan, Housing and Alt from the same person and he said they came from the same car. When I put the original model 55amp Marchal on the "newly purchased" fan set up i noticed the belt was angled back slightly and almost touching the fan housing down near the TDC mark.

[Early_S_Man]

The housing you acquired already has been machined the required 9.3 mm ... that is why the 55 A alt went so far back in the housing.

There is no significance to that particular date code. It is late enough production to have all updates and revisions.

The 980 Watt 70 Amp Marchal alternator were introduced late in 1975 model production. All 1975 fan housings were machined for the deeper alternator. The interim/transition alternators were 840 Watt in the same size housing as the 770 Watt 55 Amp Marchals, and were shipped with a 9.3 mm thick spacer. Last of the 980 Watt Marchals were fitted to 1981 models.

[74cookiecutter]

Once again, you come through!
Thanks!


Robert

[74cookiecutter]

Oh I just thought of something you might know.
Are any of the parts from the 50amp reusable on the 70a.
Should I keep the 50a for parts if the 70a fails?

[Early_S_Man]

Robert,

Yes, I would suggest keeping the 55 Amp Marchal ... and having it rebuilt. Never know when it it could come in handy!

AS far as parts commonality goes, the brush holder assembly is the only item I can think of ... a very spendy, piece, too! You can replace the individual brushes.