The Stovebolt Site Forums The Shop Area The Electrical Bay Starting 6V pos ground GMC w/ 12V batt

O.K. heres is my "new" thread........
I have a 49 GMC pos. ground. not to sound stupid (more "new") when using a 12V to start a 6V system, I know not to turn anything on(lights, switches etc.)And I assume hook up the 12V pos. ground also.
Then does it matter how long you run it while attached to 12V. ? Will it hurt any igntion parts (coil) or relays or anything if left to run awhile?

Here is a reply from cletis......
Are you jumping off a 6V battery or using a 12V in place of a battery? Definitely use neg to neg and pos to pos if using the 6V battery. I would be reluctant to leave 12V hooked to a 6V battery for long.

If you just want to start and run the engine for a few minutes, I would disconnect the battery cable from the starter and attach the jumper to the terminal and run a hot wire to the coil. This will prevent 12V from getting to your gauges.

Extended use of 12V without a resistor for your coil will result in premature points failure.

My 6V is dead and since I have to back burner this 49 till a couple other projects are further along. i dont want to buy a new 6V just to let it sit.
So to answer cletis question. I would not jump from 12 to 6 but temporarily replace 6 with 12.

If your charging system is working properly there isn't much risk in jumping it with 12v. I assume you have tried to recharge the battery you have and failed.

Yep it was put into service in 2000. I dont know how many, if any, years it was in service or just sat ?
Time is not on its side. but I tried to charge it anyway. No luck.

why is it pos - ground.I remember gm 6 volt as neg to ground and ford 6v as pos to ground.
you should be fine in starting it(with jumpers) with 12v but just disconnect upon starting. as long as your charging system is working, it will carry the dead 6v until you have to start it again
ron

GMC is differant from Chevy Why ? no clue

http://wiki.answers.com/Q/Why_are_all_American_automotive_electrical_systems_negative_ground

?????

Tim,

I'm not an electrical engineer but that article you linked sounds pretty suspicious to me. The author makes several statements that don't sound at all accurate. I wonder what his credentials are?

Stuart

He has a computer and can type. sometimes Wiki "facts" should be deleted.

Stuart,

That's why I put ????? under the link.

Here is an authoritative discussion on the topic. And, another? ?????

Tim

Tim,

I saw the question marks after I posted and thought maybe you had doubts on the credibility of the article too. I should have deleted my post....sorry.

Stuart

Stuart,

No offense taken - leave your post here.

I probably should not have posted a questionable link (or, two).

Tim

.
perhaps someone modified yours to positve to ground, but General Motors was pretty consistent across the line as being neg to ground
ron

6v GMCs (USA) were all positive ground (standard up to 1955 and optional maybe into 56). I do not know if that was the case for Canadian GMCs.

we are not such extremists up here.I have never seen a positve to ground GMC. I can remember fords as being that way as well as chrysler products
I can remember my 32 chev sedan as being neg to ground
ron

Just to add more confusion: I have an old Ford tractor that is 6v. positive ground. When I rebuilt it, I had asked the same question as to why positive ground. The Ford dealership told me that when Ford decided on positive ground, it was because it was felt that the electrodes on the spark plugs would last longer, something to do with electron transfer from the electrode to the head if negative ground were used instead. They also told me that the coil was made for positive ground, and to change to negaive ground would cause some percentage in loss of spark. Is this folklore, don't know.

I have heard that there is more body corrosion with negative ground systems, but there is an uncited claim on Wikipedia that indicates the opposite. Anybody know?

That first article has some pretty ridiculous statements in it, as noted. As for the differences between Canadian and American made GMCs, the Canadian GMCs were almost completely Chev chassis, with the exception of the bigger rigs which had real GMC motors.