6v positive ground question

[Afuente]

I bought a 47 Special Deluxe with a flat 6 which starts up and drives good.  After I started looking through the service manual and understanding the 6v system I see the battery is actually setup as Neg ground. 

 

I had to jumper the back of the light switch to get the lights to work but I am trying to understand if this will hurt the car and should I change it back to Pos ground?

 

What damage could this setup have caused if any?

[navyboy]

being switched over to negative ground should not be a problem as long other items that would need to be reversed have been done otherwise someone at some point may have thrown the battery in backwards? check the wiring at the coil and check to see if its positive or negative going to the coil to the distributor to see if other items have been switched to be negative ground.

[Lumpy]

I'm thinking that if it runs good, been driving it, someone must have changed it over. I'm not sure what happens when you hook a battery up backwards, but it can't be good. Would the starter work? I don't understand electrics all that well, but I don't see any reason to change it back. ?

 

ken.

[greg g]

When running, what does the amp gauge show? Discharge or charge?

[TodFitch]

The generator and starter will both work on either positive or negative ground. Your ignition system may not be quite as strong unless you change the polarity of the coil but that should be minor. Your lights will all work properly. The ammeter will read backwards unless the wires on it have been swapped.

 

No clue about the old tube type radios but they might work. Any more modern electronics that might have been added that have solid state (transistor) components in them will be fried.

[blucarsdn]

Actually, if the polarity of the electrical system is reversed, negative to ground in lieu poitive to ground, the engine is running backwards, therefore mileage is subtracted from the odometer.. If the radio has not been reprogramed, it will have a tendency to speak jibberish.. Of course modern mucic sounds the same no matter how it's played.... Bill

[Cpt.Fred]

tube radios work both ways as long as they still have the mechanical vibrator.

if it was swapped against an electronic unit along the way you will notice,

because it will go up in smoke (or at least the cable will that carries the current)... been there done that

[Afuente]

I did switch it to positive ground and it all started and ran good. The ammeter showed negative and the lights did not work. They had an electric fuel pump that was negative grounded to the fender and positive wire run to the positive post on the battery. The radio doesn't work.

I put it back as it was to have the lights. The fuel pump went bad so I am looking at an NOS pump to get it back to original.

Would the motor really run backwards?

[Dave72dt]

Would the motor really run backwards?

  Really?   I hope you're not serious.  You'd have to put the car in reverse to go forward and would have several gear choices to back up.

[TodFitch]

  Really?   I hope you're not serious.  You'd have to put the car in reverse to go forward and would have several gear choices to back up.

Didn't notice the smiley on that post?

[_shel_ny]

The lights not working makes no sense. Bulb filaments do not care which way the electrons flow.

[Lumpy]

I think you need a backwards cam shaft to run the engine backwards. Some dual engined boats are set up that way, so that the screws turn in different directions and the boat will go straight. Or I guess you could put the carb on the end of the exhaust pipe.

 

Three speeds and 65mph in reverse...that sounds interesting. You'll need a windshield wiper on the rear window.

 

Wouldn't switching the grounds back and forth be hard on the Voltage Regulator? Seems like I hooked an electric fuel pump backwards once, and it ran backwards. I'm not too sure that's good for them.

 

k.

Edited April 15, 2014 by Lumpy

[Afuente]

To funny, I rewired the fuel pump when I switched to positive ground. I was joking about the motor running backwards someone made a comment about it in an earlier post.

So everything should work with a negative ground but it would not be optimal. I plan to switch it back to positive ground, verify the coil and generator are wired correctly so the battery will not have reverse polarity feeding back into it. I plan to go back to the mechanical fuel pump. Is there anything else I need to do that you can think of?

[_shel_ny]

So everything should work with a negative ground but it would not be optimal. I plan to switch it back to positive ground, verify the coil and generator are wired correctly so the battery will not have reverse polarity feeding back into it. I plan to go back to the mechanical fuel pump. Is there anything else I need to do that you can think of?

I don;t think there is any need to switch back to Pos ground. If everything is wired correctly for Neg ground there will be no difference in performance of any system.

[derek_m]

my car is wired 6v positive ground. cranks over nice, lights are bright. everything seems to be fine. only thing that doesnt work is radio, not sure why. i got the car this way but if you need to see how anything is wired i could take some photos as needed.

[Ulu]

According to my 1957 Motor's manual, negative ground is now used because it generally gives a hotter spark.

 

The accumulation of electrons charging the entire car negatively gives current easier into a mere wire than charging that mere wire negative and expecting it to go the other way.

 

Remember that electrons come out the negative pole. If the whole car is hooked to the negative pole, you only have the same 6 volt potential, but available current given into any wire goes up. 

[Lumpy]

Seems like a simple matter to do that, if one desired. On radios, I once connected a CB up backwards, not a tube radio, and that thing fried it's self, made big smoke. Not so with a tube radio?

 

ken.

[Ulu]

I did that in my '64 MG Midget, with a 12v cassette player. That was 12v pos ground car & I just wired it backwards and used insulators to mount it so the chassis wouldn't touch the car chassis.

 

Well one day I shorted it clumsily and PFFFFT!!!!

 

Fortunately it only fried a choke coil right on the + in wire, which was a radio noise suppression device or maybe voltage regulation.

 

The burned coil evidently acted like a fuse, and when it performed that ultimate regulation, it protected the rest of the electronics.

 

I jumped past that coil and my chrome plated tape deck worked again. 

 

But when I cooked it, the burnt lacquer from that one small cooked coil smelled like the entire dash was on fire. LOL

Edited April 18, 2014 by Ulu

[Tom Skinner]

Ok you guys can go Negative - but I'm staying Positive - LOL

Happy Easter!

[Lumpy]

Now I forget, but how does it go when you jump start a negative ground car with a positive ground car...or visa versa? I used to know that. It's still positive to positive, negative to negative, right? Or...visa-versa?

 

I never checked that CB, figured it was toast.

 

ken.

[jeffsunzeri]

According to my 1957 Motor's manual, negative ground is now used because it generally gives a hotter spark.

 

The accumulation of electrons charging the entire car negatively gives current easier into a mere wire than charging that mere wire negative and expecting it to go the other way.

 

Remember that electrons come out the negative pole. If the whole car is hooked to the negative pole, you only have the same 6 volt potential, but available current given into any wire goes up. 

 

I wonder what they mean about "hotter spark". It's a term tossed about pretty loosely without much substantiation. At the normal 15 - 20 kv found at the spark plug, the difference between ground method is not even approaching neglibible.

 

When going to a negative ground DC system on a car you should take the extra step of making sure all the chassis components are electrically bonded more than in a positive ground system

 

Changing from a manufacturer's positive ground system to negative ground is not such a good idea IMHO.

[BobT-47P15]

Yes.....pos to pos..........neg to neg if jumping.     There are instructions in the manual i think for polarizing the 

voltage regulator and perhaps the generator.  

[BobT-47P15]

Did your headlights resume working when positive ground was returned.?

[Ulu]

I wonder what they mean about "hotter spark". It's a term tossed about pretty loosely without much substantiation. At the normal 15 - 20 kv found at the spark plug, the difference between ground method is not even approaching neglibible.

 

When going to a negative ground DC system on a car you should take the extra step of making sure all the chassis components are electrically bonded more than in a positive ground system

 

Changing from a manufacturer's positive ground system to negative ground is not such a good idea IMHO.

I do not believe it has anything to do with the actual voltage that can be obtained, but with the speed at which those electrons can be delivered.

 

If you charge the whole car, and spit electrons into it from a wire, it happens faster than charging a wire and expecting it to spit electrons out into a whole car.

 

But I'm working from an increasingly faulty memory, so I'm going to go back and refresh my memory about all this.

 

Every manufacturer eventually changed over to negative ground, so there was a very good reason.

 

Might even have to do with electrolysis of the body under wet conditions.

[Plymouthy Adams]

on a street machine and normal driving you will most likely only view that the transfer of metal on the contact point swap position with coil polarity...the other is so insignificant a matter is really only exists on paper..