12V positive or 12V negative?

Anonymous-0 · Jan 5, 2011

I have a IH 240 u and have done the 12V conversion on it that i copied of of this forum and it works perfect! But i'm not sure if i made to 12V pos or 12V neg conversion? I'm new at this and it is probably something real easy to figure out for you guys that have been in the tractor Buisness awhile, Reason for asking is I'm thinking about installing an electronic ignition and high voltage coil,and want to purchase the correct one the first time.

Bud W · Jan 5, 2011

Hi Tim
Where are you located in Texas. I'm close to McKinney. Just pull your battery box lid and see which pole of the battery is grounded.Oh I'm no mechanic by any means .Bud

Bob Evans · Jan 5, 2011

I have a 48" Farmall HV Hi-Crop that I changed from 6 to 12 volts.While at the Red Power Roundup I bought a 12 volt positive ground voltage regulator and left the pos.ground on the 12 v battery in the tractor.I also left the 6 v generator on and used a reducer at the dist.Only changed the lights to 12 V.This was 3 or 4 years ago and have not had any problems yet.If you use neg. ground and the system charges you should be ok.If not change to pos. gr.

Theman · Jan 5, 2011

I have made both the pos ground and neg ground conversions. The negative ground conversion would most likely be easier for you as it is closer to standard automotive practice of placing the coil between the battery and the points. The positive ground system puts the points between the coil and battery and is a bit more tricky to troubleshoot.

Rumplestiltskin · Jan 5, 2011

Bud's right, Tim. Just follow the ground strap from the chassis up to the battery terminal. The terminal should be clearly marked + or - (or maybe POS or NEG). If not, post again.

Mark W. in MI

Anonymous-0 · Jan 5, 2011

Hey, Bud I'm Located in Giddings, Texas Between Houston and Austin, its mostley cattle and Oil Patch Country, Thanks for the Help i knew it would be something simple!

mkirsch · Jan 5, 2011

If you installed an automotive alternator, and it is still working, then you did a NEGATIVE ground conversion, without a doubt.

Common auto parts store alternators are negative ground. Hook it up positive ground will cause the magic smoke to come out of the alternator, and it will no longer work.

rvirgil_KS · Jan 5, 2011

The points are the grounding switch in both postive and negative ground. With both polarities the wiring goes from battery "hot post" to ignition switch, to coil, to distributor where the points are located.

If using a 6 volt coil with 12 volt system a resister is installed between switch and coil to limit current.

With negative ground the negative post on coil goes to distributor. With positive ground the positive post on coil goes to ground.

Trouble shooting procedures would be the same for either polarity.

old · Jan 5, 2011

If it was done with an alternator you stand a 99% chance you have a - ground system. There are very very few alternators made that are + ground. Now if it was done with a generator then it will probably be + ground to stay with the original look

Wayne in MN · Jan 5, 2011

Sorry to say but 6 volt points are wired just the same as 12 volts. The difference is the need for resistance to cut 12 volts down to approximately 6 volts to protect the points from premature wear. Resistance is placed either before or built into the coil.
Look at a wiring diagram to confirm.

Anonymous-0 · Jan 5, 2011

Thanks for all the help!! when i got into fixing up this 240 my dad who has about 14-15 tractors told me this was the best site to get info and he was right as usual. thanks again!

LarryT · Jan 6, 2011

If it's working you have it right. I have only seen one negative ground alternator and it was a 6volt alternator that was offered on the 1952 Buick with the inline 8 engine and it had duel batteries so that you could crank the thing. Grandpa decided to convert it to 12 volt negative ground. He changed out the bulbs to 12 volt bought a new 12volt alternator and voltage regulator, and ONE 12 volt battery and about 6 months later the factory started offering the 12 volt system as a standard feature. They also came out with a kit you could buy and have an authorized shop install it. Their kit cost I think Pop said about $75.00 and another $150 to put it in. It took him 2 hours and $30 in parts, and that includes the battery, alternator, regulator, and bulbs. The kit changed the whole engine to dash harness. We never did figure out the reasoning for that. So I learned from a young age, If it ain't broke, don't fix it. LOL LarryT

Theman · Jan 6, 2011

Tim is asking about a conversion to electronic ignition, not merely going to 12-volt with points.
The electronic system uses a magnetic sensor to open the circuit and they are different internally for positive and negative ground systems.

12V positive or 12V negative?

Anonymous-0

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Bud W

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Bob Evans

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Theman

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Rumplestiltskin

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Anonymous-0

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mkirsch

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rvirgil_KS

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old

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Wayne in MN

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Anonymous-0

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LarryT

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Theman

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