Twelve volt regulator on a 6 volt generator of 1941 Cadillac

[Don Wilson]

I want to put a 12 volt generator on my 1941 Cadillac engine. Available 12 volt generators or alternators are not readily mountable on my 1941 engine. I have found elsewhere on the internet the suggestion that a 12 volt regulator is all that is needed to make a 6 volt generator safely produce 12 to 15 volts and keep the amperage at a safe level also. I also read, in a response to this claim, that such a setup will eventually burn out the field coils of the generator. I certainly am not an expert on such things, but it seems reasonable to me that the 12 volt regulator would also limit the amperage to a safe level despite current demands put on the system. In other words, if current demands were greater than the system could safely produce, it would simply begin to discharge the battery. My Cadillac 6 volt system is limited to about 34 amps; what would the amperage limit be if it were producing 12 volts? Anyone out there have any thoughts about this whole idea, other than say I should keep the car as originally built?

An alternative solution is to obtain a 1953 Cadillac 12 volt generator and exchange the front plate on it with the 1941 generator front plate so it would fit the 1941 generator adjustable mount. Are these generator front pates interchangeable?

I believe that either of the above solutions would be much easier and better looking than trying to fit an alternator to the engine.
Don Wilson

[35-709]

Perhaps this is what you need ---
http://www.gener-nator.com/    or
http://www.powermastermotorsports.com/alternators.html

Don't forget you have positive ground.

[Steve Passmore]

This has been covered many many times on this forum. The front mounting plates are not interchangeable with a standard Generator and there is no alternator that will fit them either.  Bobby B was looking into getting alternators converted to fit and there are Alternators that look like Dynamos, this may be the best way to go.  I did a conversion to the front plate years ago.It took a lot of engineering which eventually finished off the dynamo.

[Bobby B]

Bobby B was looking into getting alternators converted to fit....

Steve,
Yes....In the process. Thanks for reminding me to call the machinist. Been crazy busy at work..
                                                                                                                             Bobby

[bcroe]

I want to put a 12 volt generator on my 1941 Cadillac engine. Available 12 volt generators or alternators are not readily mountable on my 1941 engine. I have found elsewhere on the internet the suggestion that a 12 volt regulator is all that is needed to make a 6 volt generator safely produce 12 to 15 volts and keep the amperage at a safe level also. I also read, in a response to this claim, that such a setup will eventually burn out the field coils of the generator. I certainly am not an expert on such things, but it seems reasonable to me that the 12 volt regulator would also limit the amperage to a safe level despite current demands put on the system. In other words, if current demands were greater than the system could safely produce, it would simply begin to discharge the battery. My Cadillac 6 volt system is limited to about 34 amps; what would the amperage limit be if it were producing 12 volts? Anyone out there have any thoughts about this whole idea, other than say I should keep the car as originally built?

An alternative solution is to obtain a 1953 Cadillac 12 volt generator and exchange the front plate on it with the 1941 generator front plate so it would fit the 1941 generator adjustable mount. Are these generator front pates interchangeable?

I believe that either of the above solutions would be much easier and better looking than trying to fit an alternator to the engine.   Don Wilson 

My first questions would be, why do you want 12V, and do you plan to change to
negative ground? 

At the least your generator would need to be remagnetized to change polarity. 
Certainly a different reg would be needed, I think they are all designed for
neg ground.  The current limiting on the reg is for the main output, NOT for
the field coil, which was wound for a 6V input.  If you try to get the same current
out at 12V, you may experience a slipping belt at twice the torque, and probably
put more strain on the field winding. 

If you need the power, an alt is the way to get it.  But practically all the accessories
would need to be reworked or replaced, starting with a ballast resistor and reversed
coil for the ignition.  Some gauges are polarity sensitive, starting with the ammeter. 

I never tried any of this, a very simple conversion from gen to an internally regulated
alt was done on my 62.  My opinion, the mechanical issues of mounting a cheap,
lightweight 70s alt would be way less than the electrical problems created.  Bruce Roe

[Don Wilson]

G. Newcombe,
I visited the two web sites that you suggested.Either one would be a good solution, particularly the GENER-NATOR one. I wasn't looking for all the amperage that the POWERMASTERMOTORSPORTS alternators would provide, and fitting them to my mount would be more difficult than the one already in the Cadi generator case. No, I didn't forget about the positive ground.

Steve Passmore,
Thanks for answering the call for help again. I was hoping that swapping out the front plate on a later model 12v might be an easy solution, but thanks to your advice I won't get caught up in that fruitless endeavor. I think that I've come up with a solution on my own this morning. Back to that later, here.

Bruce Roe,
Thanks for your input, too. It sounds like trying to up the voltage of my 6v generator by using a 12v regulator would likely lead me to grief, too. That's why I go to you guys with this kind of question; you have more experience than I do. The answers to your first question are : I have wondered several times over the past 8 years if the 6v was not going to quite do the job. Having made too many short trips and long idles, finally about 2 weeks ago I had to get a hand push; luckily, I was at a service station lot where that could be done safely. I changed ground to negative many years ago, reversed the wiring of the ammeter, and made necessary changes to the radio, etc. A forum member had told me how easy it is to polarize the generator when changing the ground. Incidentally, only the ammeter gauge is polar sensitive.

Now, the good news:
Other than that maddening 6v slow grind of the starter, I am pretty satisfied with the 6v operation. I use the right size battery cables, rewired so the lights are all bright enough and a fire behind the upholstery is unlikely. For many years I have used an ORPIN battery switch for starting my 1951 Frazer, but now the 6v/12v version is no longer being manufactured. This morning , during my coffee and donuts, I thought of an alternative to the ORPIN battery switch. It requires one 6v starter relay, such as used for 6v Fords (3 pole, normally open) and that is all if you don't mind doing a few manual things every so often to recharge the second battery as required. If you want fully automatic switching from parallel connections for charging to series connection for 12v starting, two "normally closed" 3 pole relays are also required. I was apparently WRONG IN SAYING THAT ALL OF THESE RELAYS ARE AVAILABLE NEW; ONLY THE 6V, 3 POLE, NORMALLY OPEN RELAY is available new. CAUTION: I haven't actually tried the above solutions yet on my Cadi, but I believe most of you will be able to see the feasibility of the solutions. Incorporating the switching from automatic series mode for starting to switching to parallel mode for charging both batteries is, naturally, most susceptible to failure which may cause unexpected loss of battery charge, or even electrical fire. Try this cautiously and at your own risk.
Don Wilson

[bcroe]

I believe the alternator does better for a lot of idling; a modification of the
pulleys might spin the old gen a little faster to help.  My alt conversion needed
way less maintenance, put out a lot more power, and didn't generate any radio
noise. 

I'm surprised your radio needed modification for a polarity change, unless it
was already changed to solid state. 
good luck,
Bruce Roe