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6 volt negative ground?

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jpf

01-21-2001 14:35:24




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I looked at a 2n today it had a 6v batt. with a negative ground. I have seen this tractor running before is this possible? are their some questions I should ask owner before I buy? seems like if it was pos. ground to start with starter would turn backwards now! thanks for any info to this newbie on the board.




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Claus

01-21-2001 14:51:12




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 Re: 6 volt negative ground? in reply to jpf, 01-21-2001 14:35:24  
People do this who cannot make the paradigm shift of having a negative ground. There is no advantage to switching ground. Actually, there is some degradation of spark current since one cannot easily change the polarity of the coil.(front mount) Spark current is optimal if the center spark plug electrode is negative in respect to the chassis. This is because the center electrode gets hotter and will give off more electrons. That is why they put plus and minus on coils...Since the current is also reversed through the field then the starter motor will turn over in the correct direction regardless of polarity. The generator will also work provided it has been properly polarized. Happy Motoring
Claus

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jpf

01-21-2001 15:19:16




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 Re: Re: 6 volt negative ground? in reply to Claus, 01-21-2001 14:51:12  
thanks claus, do you recomend changing back to pos. grnd. if so how would I re-polarize the generator?



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Claus

01-21-2001 15:49:23




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 Re: Re: Re: 6 volt negative ground? in reply to jpf, 01-21-2001 15:19:16  
You would momemtarily touch the battery negative terminal to the field coil. On the N tractors the high side of the field is accessible through the output teminal (The only connection on the 2N/9N) on the 8N, the terminal on the end plate (marked Arm or Gen) for about 2 seconds. The easy way to do it is on 9N/2N is to connect a jumper wire from one side of the cutout relay to the other. On the 8N, it is done by jumping Bat terminal of the regulator to the Arm terminal of the regulator. Be careful not to touch the field terminal on the regulator with bat voltage. I would not run out in the cold to do it but would wait until it got a little warmer. If you have a side mount distributor ensure that the plus side of the coil goes to the distributor. The leads on the ammeter would also have to be reversed. Happy Motoring
Claus

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jpf

01-21-2001 16:15:32




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 Re: Re: Re: Re: 6 volt negative ground? in reply to Claus, 01-21-2001 15:49:23  
thanks much claus for the info and in such a speedy manner. I hope I can be of some help to you in the future. jpf



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Don Johnson

01-21-2001 18:23:40




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 Re: Re: Re: Re: Re: 6 volt negative ground? in reply to jpf, 01-21-2001 16:15:32  
My 1944 2N was also neg ground when I bought it 3 years ago and it runs and starts great. It starts just as fast at -30 as it does at + 80 and it does get -30 here in the upper penninsula of Mich. I would leave it alone. Just my 2 cents worth.



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Claus

01-22-2001 07:04:56




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 Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Don Johnson, 01-21-2001 18:23:40  
When the plug is cold, coil polarity has no effect, so one does not see a difference in starting. Once the plug gets hot, you will get slightly better combustion with the correct coil polarity. One may not notice this small difference. On the other hand, when engines get wear on them and the compression drops by 10 psi, you may not notice that either. A loss of a HP or so is not noticable to most people. But the loss is still there and if the timing is off a a couple of degrees, you may not notice that either. Again, you will not get optimum performance. If you put all of these conditions together, one may notice the difference. That is why some tractors run better than others and do not pull that plow as well as when the tractor was new. Things Usually deteriorate one straw at a time..
Happy Motoring
Claus

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Salmoneye-Claus Has It Right :-)

01-22-2001 05:45:17




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 Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Don Johnson, 01-21-2001 18:23:40  
Henry Ford knew well about the Edison Effect, and that is why early vehicles (including N's) were all positive ground.
This has to do with the proclivity of the electrode of the spark plug wanting to be negative and wanting to 'ground' to a positive block.
With ground being negative, you are actually losing some spark potential with a 6-Volt system.
With todays higher voltages (12-Volt), this is not as much of a problem.

If you are starting fine below zero with negative ground, more power too you!
However, sometimes on a marginal system, it could mean the difference between starting or not.

Just my two cents worth...

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Nolan

01-22-2001 18:04:28




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 Re: Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Salmoneye-Claus Has It Right :-), 01-22-2001 05:45:17  
Not by a long shot were early cars all positive ground. It was split about 50/50 between negative and positive grounds from the very begining.



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Phil (AZ)

01-22-2001 13:38:49




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 Re: Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Salmoneye-Claus Has It Right :-), 01-22-2001 05:45:17  
YES "Henry Ford knew well about the Edison Effect" but he (Edison) knew Nothing about "Super Conductivity" and the movement of electrons in solids

I would think the fact that the Coil has the Secondary and Primary connected together (on one side) and its this side that should be connected to the Dist Points, is much more important

IF you have a coil designed for + ground, connect the + marking on the Coil to the DIST points, regardless of the polarity of your battery.

JMHO

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Claus

01-22-2001 06:52:28




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 Re: Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Salmoneye-Claus Has It Right :-), 01-22-2001 05:45:17  
Thanks for your comment. Actually, the coil primary has nothing to do with whether one has a positive or negative ground. If the tractor in question has a side mounted distributor, then when one changes the polarity of the ground to negative, and changes the polarity of the coil as well, (negative of coil towards the points) then the net effect is zero. My comment concerns the front mount tractor coil. With this coil, it is extremely difficult to change primary polarity since only one terminal is accessible. What we are looking for is a voltage that is negative in respect to ground and the polarity of the ground is of no concern since the low side of the coil is connected to the frame through the points. (When the points are closed and the polarity of the coil is correct.) Even if you look at 12 volt coils used on automobiles, you will see polarity markings on them. The operative statement is in "respect to ground" I hope I cleared up this point.
Happy Motoring
Claus

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Claus

01-22-2001 06:51:54




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 Re: Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Salmoneye-Claus Has It Right :-), 01-22-2001 05:45:17  
Thanks for your comment. Actually, the coil primary has nothing to do with whether one has a positive or negative ground. If the tractor in question has a side mounted distributor, then when one changes the polarity of the ground to negative, and changes the polarity of the coil as well, (negative of coil towards the points) then the net effect is zero. My comment concerns the front mount tractor coil. With this coil, it is extremely difficult to change primary polarity since only one terminal is accessible. What we are looking for is a voltage that is negative in respect to ground and the polarity of the ground is of no concern since the low side of the coil is connected to the frame through the points. (When the points are closed and the polarity of the coil is correct.) Even if you look at 12 volt coils used on automobiles, you will see polarity markings on them. The operative statement is in "respect to ground" I hope I cleared up this point.
Happy Motoring
Claus

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Salmoneye

01-22-2001 14:40:27




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 Re: Re: Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Claus, 01-22-2001 06:51:54  
Hi Claus,

I was not speaking of the primary, but the secondary.
It is my understanding that the induced secondary 'wants' to go to a positive ground.
It was my understanding that this 'proclivity' is what is refered to as 'The Edison Effect'.
Not only does it have to do with the life of the spark plugs, but the potential 'heat' of the spark itself.
There are discussions on this in the archives where it has been stated that the difference may be as great as 25% loss of potential spark when the block is negatively grounded.

Please correct me if I am wrong, as I am only trying to understand.

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Claus

01-22-2001 15:29:05




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 Re: Re: Re: Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Salmoneye, 01-22-2001 14:40:27  
When you have 15,000 volts it matters little to the ground side whether the ground is positive or negative a couple of volts the potential difference is still there. The point that I am trying to make is that the high voltage pulse, should be negative in respect to ground. The center electrode since it gets hotter will more readily give up electrons like in a vacuum tube. The electron flow is from cathode to anode. The cathode is heated to facilitate the emission of electrons. When we talk about spark ignition, it is the current that does the job. Naturally, one needs lots of voltage to be able to jump the gap,
The amount needed depends on the gap size and the dialectric strenght of the gasses between the electrodes. As gases are compressed, the dilectric strenght increases so therefore the spark has to be higher in voltage. That is why you may see spark when you test the plug outside of the combustion chamber and the spark is weak, you will see spark, but it may not work in the combustion chamber when under pressure. Under the Ping Pong Theory of combustion, the striking of molecules by electrons will cause the start of combustion process. Happy Motoring
Claus

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Brad

01-22-2001 19:54:06




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 Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Claus, 01-22-2001 15:29:05  
Have you ever seen an old Champion spark plug tester that tested the plug in a chamber pressurized with shop air?

On newer cars with DIS they run two plugs off of one coil, one is negative and one is positive. You can see the KV difference between power and waste spark on a scope. About the only other difference between positive and negative is that one plug wears from the center electrode ( not much) and the other wears from the side.

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Salmoneye-Thanks Claus!!!

01-22-2001 15:51:08




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 Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: 6 volt negative ground? in reply to Claus, 01-22-2001 15:29:05  
Appreciate the clarification!!!



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