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electrical question

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JimTVC

05-02-2007 15:10:12

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Maybe its obvious but I want to be sure. I have an 8N,converted to 12 volts but I still use a 6 volt coil with a resistor. Front mount distributor. The black negative terminal on the 12 volt battery grounds to the tractor. Is this considered a 12Volt negative ground system? When I look at electronic ignitions they refer to various categories such as 12V negative ground or 12 V positive ground, or 6 volt negative ground etc... That's why I want to be sure what mine is. Thanks

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Dell (WA)

05-02-2007 15:34:18

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Re: electrical question in reply to JimTVC, 05-02-2007 15:10:12

Jim..... ...amazingly enuff, electrons don't care what color the wire is, but black is typically electronics ground, but in house-wiring, white is cold (ground) and back is hot. Modern automotive wiring, ground is brown.

And even more amazing, resistors don't care positive or negative ground. Amp-meter don't care either but you do. Amp-meter always indicate (+) for charge, whether positive or negative ground. PLUS (+) for CHARGE. Iff'n it don't indicate plus, just swap the amp-meter 2-wires around. Simple, eh?

NOR does the battery care, positive (+) or negative (-) ground; ...BUT... the 12-volt alternator DEMANDS NEGATIVE GROUND. Sumptin' to do with the solid-state guttz of the built in voltage regulator and the DIODE trio. Incorrect grounded alternator lets the smoke out. Therefore it is to your best interest to NEGATIVE (-) GROUND yer 12-volt battery.

tip: molded into the top of the battery is a PLUS (+) for positive post; and a MINUS (-) for negative post. Wanna guess which battery post you should connect to rusty old ground??? ..... ..respectfully, Dell

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Peter, Covington, LA

05-02-2007 15:16:37

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Re: electrical question in reply to JimTVC, 05-02-2007 15:10:12

You've got it right - that's a 12 volt negative ground system. The only reason it's important is that 12 volt alternators only come in negative ground - the old generator used on 6 volts could be polarized either way.

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Peter, Covington, LA

05-02-2007 15:20:43

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P.S. in reply to Peter, Covington, LA, 05-02-2007 15:16:37

Other than the alternator, nothing on a tractor cares which way it's polarized. Certainly light bulbs don't, and the ignition coil wouldn't care either. The starter runs the correct way with either polarity. It's possible the points will burn more quickly one way than the other, and if that's so I'm sure others will correct me. But, negative ground is the "right" way regardless.

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Jerry/MT

05-02-2007 19:00:22

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Re: P.S. in reply to Peter, Covington, LA, 05-02-2007 15:20:43

Not true about the ignition coil. The wire from the coil to the distributor must be connected to the coil terminal with the same sign as the battery ground or the spark energy is reduced by about 50%.

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Phil (NJ,Az,SasK)

05-03-2007 15:23:47

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Re: P.S. in reply to Jerry/MT, 05-02-2007 19:00:22

Jerry, If you, or anyone, have a legitimate source for that statement. A trade publication, IEEE paper etc, please quote the source. I am never to old to learn a "NEW" body of theory

All Waste spark systems, on today�s cars, fire the pair of plugs with both -ve & +ve hi voltage.

Some 1930-1940's cars had a switch to deliberately reverse the current through the points & coil primary. This practice was discontinued when points & plug material was changed/updated such that the One-Way material transfer was not an issue.

Old Wives Tales make some PPL smile but they don't fix "real" problems.

JMHO

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Jerry/MT

05-03-2007 20:31:39

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Re: P.S. in reply to Phil (NJ,Az,SasK), 05-03-2007 15:23:47

I don't know much about old wives tales and my engineering degrees are not in EE but here's a reference:Motor Auto Engines and Electrical Systems Library Of Congress catalog number 77-88818 ISBN 0-910992-87-8 p.586 "Importance of Correct Coil Polarity" I hardly think this is new theory as these type of ignition systems date back to at least the 1940's.

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JimTVC

05-02-2007 15:29:01

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Re: P.S. in reply to Peter, Covington, LA, 05-02-2007 15:20:43

Thanks Peter. That was sure quick. I thought it was but wasn't ready to invest any $$$$ in anything until I was sure. I'm debating the electronic ignition changeover to do away with the points etc. I'm wore out over time struggling with the ignition issues. It always seems to be something and it always seems to happen on the sunny day when I need it to run.

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