I have been trying to determine whether I should proceed on the production and marketing of the Tach Driver we have developed that allows the use of readily available 12 volt negative ground tachs on 6 volt positive ground systems. Being a Ford guy, I assumed that all 6 volt systems are positive ground. I quickly found out that Chevrolet 6 volt systems are negative ground; who knew? Can you guys that know post which systems are which ground? e.g Mopars? other 6 volt GM cars? Kaiser-Fraser? O/T foreign makes? Thanks, Tubman
funny story. 1970 I had just bought a really cheap (25$? 50$?) wornout 1950 Stude bulletnose because I thought it looked so very weird, and a h.s. buddy drove me over in his 52 Chevy to give the Stude a jumper and make sure I made it home. After a whole lot of cranking and fiddling with the carb, I got the Stude running and idling ok, but left the jumpers hooked in case it died again. My buddy opened the door on his 52 Chevy to get out, letting his car door touch the Studie bumper. He really freaked out when he saw the sparks and flashes as the two cars tried to weld together. It was so funny. We draped a coat over my bumper so it wouldn't happen again. why be ordinary?
The 52 Chevy was 6v neg ground, and the Studie was 6v pos ground. When the door touched BOTH cars had a dead short across their battery terminals. why be ordinary?
Until the change over to 12v which occurred between 1953-1956, most cars were positive ground, including: Mopar, Ford/Mercury/Lincoln, Cadillac, LaSalle, GMC, Packard, Hudson, Nash, Pierce Arrow and Studebaker, were all positive ground Model T Fords were negative ground and Ford changed over to positive ground with the Model A's. Also negative ground were Buick, Chevrolet & Oldsmobile I believe most imported cars of that period were positive ground, too.
If I'm not mistaken, many old british cars are positive ground. Lucas electrical systems, most famous for being unreliable.
My/The 1951 Henry J is supposed to be POSITIVE ground, it was/ has been NEGATIVE ground, for the last 35 years that i've owned it. I did NOT make the switch/turnaround, OBVIOUSLY it CAN be done. .
You might try this site with a lot of basic specifications for a lot of different vehicles. It shows vehicle voltage and ground requirements. http://www.carnut.com/specs/specs.html For example, these 1940's vintage Oldsmobiles. http://www.carnut.com/specs/gen/olds40.html
6 volt positive ground just never looked right to me, all my 55 Chrysler. had damaged relays, I assume as a result of being jumped with a 12 volt negative ground. Years ago I bought a 1950 Ford Woodie with the battery hooked up positive ground, to correct this I turned on the headlights until the battery was completely dead, then reversed the terminals.
I can understand the change to 12 volts - engine compression ratios were on the rise for one thing, and new accessories hogging lots of juice. But why the wholesale change to negative ground? What was the reason offered at the time?
"Claymart", thanks for the link. There's a lot of interesting information there. "Truck64", I think I read somewhere that positive ground is a little more efficient and you need everything you can get with only 6 volts. I know there is an explanation, but I don't remember where I saw it. Don't worry, on this site, someone will come up with it. Thanks to everyone who answered. I have the information I need now. I really never considered the existence of 6 volt negative ground.
Here's a five (5) page discussion on the "why" negative ground, though it seemed to mostly revolve around which way electrons flow. So I'm not sure any definitive reason was given. https://www.jalopyjournal.com/forum/posts/5487771/ And this was kind of a big deal at the time, I'd expect, just considering the fact virtually every manufacturer decided to drive on the other side of the road, so to speak. I don't get it. Flouride in the water? Commies stealing our precious bodily fluids?? Elvis didn't join the Army till '58, so that's not it.
Technically, Lucas didn't invent darkness. But I do believe they perfected it and hold a lot of the patents for it.
The switch from pos ground to neg ground had to do with the use of more and more electrics in cars. Transistors and other devices prefer the neg ground. For basic car functions it really doesn't make any difference as long as the few components that it matters to are adjusted for it, coils, generators, etc.
Just join the neg. ground crowd ,it's been the convention for more than 50 years now. .......... Jack
Model J Duesenbergs are positive ground. They don't need a tach upgrade though, all came with cable-drive rev counters off the back of the right cam (yes, 2 cams).
Positive and negative are simply words. Exchange the word defination and nothing changes, the electrons are just as happy.. Absolutely no performance outcome has been proven better one way or the other, regardless of ill-founded theory, whether transistors or motors or coils or generators. Same identical performance results are had either way. A few welding circumstances aside boways. But some folk are neverteless bothered by the concept of 'positive grounds', I think it has to do with something in their infancty that their mothers fed them as later in adultery, they choke on the thought. For me, a 'negative ground' sounds dastardly ill founded while 'positive ground' has the ring of sweetness.
Chev cars were negative ground, trucks were positive. Go figure! Boats are positive ground, has something to do with reaction to salt water and electrolysis.