Technical 1954 Ford Positve Ground Vs Negative Ground

Funny how old six volt systems were the only thing around in the early days...We drove them and had very few real issues about the same as today... Little hard starting in below zero Ohio winters but it was all we had...Time moves on...

 

ill do whatever i gota to chill the beer !! when i was growing up , we were so poor . no a/c . had to run the heater year round !

 

real life i always run everything neg ground .and if the amp guage is backward .switch 2 wires .ive never noticed any outher difference .im not sure about reversing the coil either . but i switch to 12 vqlt asap and run a 12 volt coil without a resistor . maybe the points burn faster ,but im not sure thats true !

 

I assume you're pulling our collective chain.

If not, then I hope you don't own jumper cables.

 

DC = direct current, no frequency. AC = alternating current, has a frequency, usually in the USA 60 cycles. But I know he was pulling our leg.

 

Hi, just to note if you have 2 batteries connected in parallel, they have to be matched. A new battery and an older one will buck each other at times. The weaker one will pull down the stronger one. Found this out the hard way on a 1980 Chevy pickup with the Olds 350 diesel in it. After having this bandit problem 2 fresh batteries cured the problems. Was told by an electrical engineer batteries can have different resistance there fore one can pull the other one down. May not apply here but as some one said charge them up separately and see if either drain at different rates. Thanks.

 

This was my understanding as well. Had something to do with galvanic response. Ahh, here it is.

"It is partly a matter of convention and standards, and partly because positive earth encourages galvanic corrosion* of the surrounding bodywork - whearas with negative earth is is the much-easier-to-replace electrical contacts that corrode."

 

Grounding has always been a poorly understood aspect of electrical theory and most accumulated knowledge on the subject has been gleaned from observed results with best guesses by the engineers as to why whatever happened. I've seen grounding designs go from being required to illegal when it was discovered that under certain conditions it didn't act the way they predicted. I occasionally had opportunities to pick the brains of engineers on this, and this is my take on it...

It was generally assumed that power flowed from positive to negative. And it is true that all electrical devices are series circuits; power flows in on the positive conductor, voltage is dropped across the device/load, and the remaining voltage returns on the negative. Current in/out of the device remains the same. What goes on inside the device has little bearing on this. For efficiency of the circuit, unwanted voltage drops are reduced as much as possible/practical by using an adequate-sized conductor.

By using a chassis ground, you have most of the vehicle structure as a ground path. While steel is a poorer conductor compared to other metals like copper, it really has more to do with conductor cross-section. A large steel bar can have a lower resistance than a small wire. And electricity will take the path of least resistance. So on the face of it, a positive chassis/body ground should deliver power easily with it's large overall cross-section.

Where this breaks down is the chassis/body ground isn't a single continuous conductor. It's dozens of pieces welded/bolted/riveted together with usually an attempt to make it electrically continuous but there's a ton of factors working against that. Even at best, the engineers were unable to accurately predict just which path would be taken. As @gimpyshotrods notes, with the introduction of electronics, or more specifically solid-state electronics, delivering reasonably accurate input voltage became more important and was easier to attain with a negative-ground system using a defined path for the positive input power.

 

My question was going to be a post at some point along the same lines. Bought an old 1956 Plymouth that should be 12 volt negative ground. It had an earlier Dodge little Red Ram Hemi in it and it looked by the battery terminals it was still a positive ground. Been running the motor like that and my question was or would be does the distributer know the difference which way it's going or I'm I over thinking too much ?

 

He can but they are , red and black leads. Reversed polarity from the todays standard. Ah, you would have to be a rocket scientist or brain surgeon to understand the reasoning. I don't.

 

The distributor doesn't care, but the coil might. Some coils are polarity-sensitive because of how they're built internally. Generally speaking, if it is polarity-sensitive it won't work right when reversed.

 

Agreed, a lot of people don't understand how a coil is wired internally.

 

Disconnect one of the battery cables and put a multimeter in between the cable and battery and measure the current draw (Milli-Amps or Amps) when everything should be off.
With ~zero current draw showing would indicate that the batteries and/or generator are the problem.
If some current draw is seen start disconnecting different circuits individually until the current draw is found.

 

Ignition coils always polarity sensitive, and the weird thing about it, this has absolutely nothing to do with whether the car is positive or negative ground.

The reason it matters is the way a spark is initiated at the plugs. As it happens electrons "like" to jump from a hot surface to cold, meaning in this case from the center electrode to the ground strap. It takes a lot less initial voltage to fire the plug in this arrangement, which is what we want.

If the coil is connected "backwards" it will still work, but the spark output is reduced by about 25%, maybe not an issue under idle conditions but could be a real problem under load.

If you're like me, upon being informed of this, you may find yourself laying in bed at night unable to sleep wondering "Are my ignition coils running at the proper polarity!?", this uncertainty, well that just won't ever do now will it? Of course not.

Dirty dishes might be piling up in the sink, but never mind that let's get our priorities straight, get out there in the garage and check! You can easily test for proper ignition coil polarity without regard to any markings on the coil with nothing more than a pencil or, an old school analog voltmeter. Here's how to do it:

https://mgaguru.com/mgtech/ignition/ig104.htm

 

Yep - I think it's crazy too but the old girl will yard drive and actually starts purrring a little before I have to shut it off.

 

as i understand it the + post of the coil is attached to the ignition switch wire
and the - post is to the points which gets grounded when the points are closed.

the coil terminals are NOT marked in reference to positive or negative ground.

 

Right, they were marked + and - or "Bat" and "Dist", but it might be questionable at least in the mind, when dealing with really old ignition coils and/or converted electrical systems. It's really easy to check and remove any doubt.

 

This is true. We run 4 batteries in the semi trucks, one bad one will pull the other three down overnight.

 

Yes the electrical engineer at work said every battery has internal resistance. They can perform quite well by themselves but if you tie them together and if there is a great difference between them one will pull another down. Just helped out on a Ford dually diesel for a friend with this problem. He mixed a used battery with a fresh battery. He did not believe me explaining they will both charge up just fine but overnight the truck could barley crank over. Kept charging them every day. He thought he had a short somewhere. I had him put another fresh battery in her and guess what no more problems! My 80 Chevy Diesel dual battery pickup had an isolation block in her for the same reason. You never stop learning or at least i do not. This site is a bible of knowledge!!

 

Yeah, people don't seem to grok that a battery is a collection of cells, and you aren't running "2 batteries" or "4 batteries" electrically speaking. It's easier to say it that way, but they really don't seem to understand this and think they can re-charge them both with a $3 wall wart charger after getting smoked. Not a chance. Same thing with the alternator after a jump start, they will never get anything plussed up, and might get damaged trying.

Even the instructions that come with a flashlight say don't mix and match old and new cells. It will work, but the light flickers, and then one of the cells starts leaking, etc.

 

Well it helps to keep + to + and - to - though.

 

True on older ignition systems. The center electrode was always negative so the electrons could jump to the positive ground electrode (electron theory vs. conventional current flow). However, with the advent of electronic ignition and coil packs directly on spark plugs (similar to a Model T) some ignition systems actually fire the plugs the opposite direction. I think it boils down to how much available voltage you have. If it is high enough, you don't care which way the plug fires it's going to make a spark no matter what.

 

jaracer, you are delving into non-HAMB stuff and getting away from the OP's issue, but I had to mention some systems also fire in a loop thru 2 spark plugs, center to ground on one, then ground to center on the other. This is the main reason 'double platinum' and such were made.