Probably a dumb question

[Alan_Hepburn]

Thanks for the help, guys - I talked to my son and he says he wants to update the electrical to a 12V negative ground system with an alternator instead of a generator. I've never done that before - I know that we'll have to get an alternator, coil, and regulator. Do we need to specify a particular model of each, or do we just select them at random? Should we swap out the starter or is it safe to spin it with 12V instead of 6V, and what are the implications of +12V vs. -6V? Does the starter want to spin backwards?

This is all new to me, so the questions are probably funny to many of you!

[FourDoor]

If ,as you say, the system was actually postive ground then the generator will have been destroyed along with the 3 regulator relay point sets. It would have badly burned the armature segments and brushes in the gen. and fried the points on the cut-out relay and the voltage and current control relays in the reg. The reason is that the generator has to be re-magnetized in the negative direction if the system is to be run with negative ground after being run in the positive direction. Otherwise the generator would appear as a short across the battery and the regulator as soon as the engine is run. The re-magnetizing procedure is called 'polarizing'. Plus if the gen. and regulator were 6 volt units and they were run on 12 volts then the question of polarizing is redundant. A 6 volt starter motor can be run on 12 volts because the run time is so short-usually. If the coil was a 6 volt unit then it too would now be fried. Even if the terminals show a resistance on an ohm meter the internal shellac will have melted and windings will be shorting together and it won't produce a spark now. The ignition condenser is rated in hundreds of volts to take the backlash from the coil so it won't have been harmed running on 12 volts. If the radio is of the old vibrator/vacuum tube type then it will run on either polarity but the 12 volts would open the tube filaments and fry the vibrator of a 6 volt unit.
? ?I would start by disconnecting the armature and field terminal connections both at the gen. and the regulator. These are marked 'A' and 'F'. Also disconnect the battery terminal at the reg. ,this is marked 'B'. Tape up the 'B' lead to keep it from shorting to ground. This will isolate the charging system which you don't need to start and run the engine. A fresh coil is a necessity. One that you KNOW will put out a spark. Although the coil will work in both polarities, it will work best in the polarity it was designed for. I'd use a 6 volt positive ground? unit and put in a 6 volt battery in that direction. When you turn the key to the run position you should see a small deflection on the ammeter indicating the current flowing through the coil. There is one caveat to this and that's if the points happen to be open at the point the dead engine is sitting then the ammeter won't move. If you then crank the engine over , the ammeter should show a small wavering deflection as the points open and close as the distributor turns round. Pour a LITTLE raw gasoline down the carb throat and ,with the choke on full, the engine should catch and run for a few seconds. If it does then you're home free and it should be obvious what's broken and what new parts you need.
? ? Remember the 'polarization' thing when you start hooking up the gen. and regulator. Just before you run the engine with the charging system hooked up again, jump the 'B' terminal , with a thick wire, over to the 'F' terminal on the regulator. Just do it for a second and there will be a small spark when you do. This will polarize the internals of the generator to the polarity of the battery direction. CAUTION; If you're unsuccessful in polarizing for some reason, the very first indication when the engine is run is the ammeter needle pinned in the discharge corner 'down hill'. You will also hear an ungodly whine from the area of the generator. If you leave the inspection/adjustment cover band off the aft part of the gen. while doing your first start-up,you will also see a ring of blue/yellow flame as wide as the brushes completely covering and flowing around with the armature segments.? ?SHUT OFF THE ENGINE.? ? This is THE indication the? polarizing is opposite to the battery direction and the battery is discharging completely to ground through the gen. armature.? But I don't suspect you will have any problem as the above procedure for polarizing is fairly bullet proof. Good luck.? :D? ? ? ? ? ?

[Go Fleiter]

No dumb Question at all, Alan!

plus or minus ground makes a difference with the Radio and the Regulator. There is a regulator changing procedure description somewhere in this (or P15 D 24 forum?).

Maybe the Ignition Coil has gone after a long 12 V mistreatment. Spark plugs, distributor, starter Motor, starter solenoid  etc. will survive. Maybe the regulato  is shot, generator should stand 12 V , at least for a short time. Lamps, Radio, wiper and heating motors may go broke only after a while with 12 .

Only during the seconds of starting procedure, I give 12 V to Ign Coil and  Starter Motor with no problems since a couple of Years (needs second 6 V Batt plus relais for coil change 6/12 V plus batt charging device at home because charging by generator needs very strong relais and is not really necessary for a 3 weeks holiday.)

Good Luck! Go.

[Alan_Hepburn]

Hello, all - I'm new here so please be gentle! My son recently bought a 1950 Plymouth that he is trying to get running. It's been somewhat modified by the previous owner - lowered, chopped, suicide doors, etc. It's still got the original 6 cylinder engine and 3 speed tranny, and we're trying to get it running. When he bought it, the previous owner dropped a battery into it and drove it part way to our house, but it quit running and had to be towed the rest of the way. Today I was helping him put a new ignition switch in because the old one came apart, and I noticed that the generator is marked as a 6 volt unit, so I assume it still has the original 6V positive ground system.

My questions:

1. Has any damage been done to anything by connecting a 12V battery into the system with negative ground? It was running for a while, but has the generator, starter, or anything been damaged?

2. Would it be better to keep it as a 6V system, or should we convert to 12V negative greound? If so, what needs to be changed at a minimum?

I'm sure I'll come up with more questions as we dig into this thing - thanks in advance for any help that might be forthcoming!