The output is determined by the adjustable third brush. It is however not regulated but rather the output can be preset by changing the third brush position. Also the rpm of the engine will affect the charge rate . Too low an rpm or heavy draw at low rpm will cause the cut-out to open (cut out) . Raising the rpm and lower draw will cause the cut-out to close and output to increase with increased rpm but only to the max limited by the third brush position. The type of driving you do needs to be considered when setting the third brush. The 935V is correct for a Master model- the standard uses a 946 but the operation is the same. 

When I drive to town, I'm usually driving at 35-45 mph and the only draw is the engine itself.  What/where is this third brush?  Is it something I can do and how do I know which way or how to adjust it?

Ken

The information you need to adjust the third brush of the generator can be found in the shop manual. There are many vendors that carry reprints and you'll also find them on ebay.

Another source of info is to search the old forums using the Advance Search Function at https://vccachat.org/ubbthreads.php/search.html

I searched the 1933-1936 forum using +adjust +third +brush as the search criteria and found a number of thread that discuss this topic.

FYI, here's some tips on how to use the old Search Function: https://vccachat.org/ubbthreads.php/topics/366696/search-function-tips.html#Post366696

Cheers, Dean 

Reading some old posts, they say that the generator on the 36 Master goes through a resistor on the headlight switch.  Could that be the problem? 

@bowtiefan 

Hi Ken

Yes that could be a contributing factor.

The field current runs to the light switch and through a resister to ground when the lights are off.

When the lights are on, the resister is bypassed and the the circuit goes direct to ground.

If the switch doesn't break that direct to ground circuit with the lights off, the charge rate will of course be too high.

Try disconnecting the field wire that runs to the light switch.

The charge rate should drop to zero.

Have you figured out the third brush and how to set it yet?

I think I have figured out how, I just haven't had a chance to get into it yet.

Ken

I 'found' the third brush and it was about 1 1/2 bars from the nearest brush.  I moved it to about 2 bars.  Now it shows about half charging instead of a full charge, so should I move it more?  It doesn't seem to move as the rpm increases, which makes me suspect the resistor on the headlight switch.  My headlight switch only works sometimes, so I know I have replace it or clean it, in either case I need to remove it.  Can the resistor be checked or should I just replace it or?

Ken

@bowtiefan 

I posted this a while back on another thread:

PPS

Actually, I just stumbled on Chevrolet's own recommendation.

With the engine running at what would correspond to 25 mph, turn on the lights and set the third brush until you see a maximum charging rate of 3 amps.

This should give the recommended average charging rate of about 12 amps (which seems somewhat high to me).

Hope that helps. 

@ole-olson I think that recommendation was fine for the times when made however today with older drivers and vehicles and the not so great headlamps most  will not drive at night . My thoughts are that three to five amps w/o headlights would be more than sufficient unless you are doing short trips only with multiple off and on starts.

@steve-d 

Hi Steve

Agreed, which is why I noted it seemed somewhat high to me.

However...

Some of our old vehicles don't run many long trips.

Lots of short trips to the ice cream shop etc.  🙂

And, often they are cranked long enough to refill the carburetor with gas when starting.

For those I'd probably stick to at least 5 amps.

As you point out, and I should have mentioned, it all depends on the type of driving the vehicle sees.