6volt gen to 12 volt gen

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dtoots1
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6volt gen to 12 volt gen

Post by dtoots1 » Thu Aug 09, 2018 8:40 am

am working on Farmall H...it had alternator on it that got knocked off and torn up..has coil and resister....12volt gen will get under hood which alt did not...need to check if any way to find coil volt? or replace to known 12 volt w/resistor..and then how wire? and which ground + or - ? course new wiring etc.

thanks,
dtoots1

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Stan Disbrow
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Re: 6volt gen to 12 volt gen

Post by Stan Disbrow » Thu Aug 09, 2018 9:47 am

Hi,

Hmmmm. Every IH Farmall letter series I have been around have been 8 volt positive ground. Yup. Eight volts. They had to have two more volts than their competition. :P But, I am not an expert on things IH. When did they go to 8v from 6v, and, then to 12v? I do know that 8 volt batteries are still available for them. Lots of them still in use...

Stan
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Have: '58 JD 420c 5-roller w/62 inside manual blade
Have: '78 JD350C w/6310 outside manual blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Also Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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Lavoy
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Re: 6volt gen to 12 volt gen

Post by Lavoy » Thu Aug 09, 2018 10:04 am

IH stock was 6 volts, 8 volts was band aid fix someone came up with a long time ago that doesn't really work without some modifications.
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dtoots1
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Re: 6volt gen to 12 volt gen

Post by dtoots1 » Thu Aug 09, 2018 11:56 am

any answers? wire same as 6 volt and use neg ground, need details

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Stan Disbrow
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Re: 6volt gen to 12 volt gen

Post by Stan Disbrow » Thu Aug 09, 2018 12:08 pm

Hi,

That someone was IH themselves. :P There were different part number Delco units for 8v.

If you are using original gen and mechanical regulator, needs to be 8v positive ground, most likely. if you are using some other 12v gen and regulator, they can be either positive or negative ground. But, 12v is really most likely negative ground. The early 12v were positive ground for only a couple years. We had a 1950 Ford truck that was 12v positive ground.

All depends on the make and model of the generator and regulator you have on hand. That would need to be looked up to be sure. There are no hard and fast rules during the decade of 1950. I can say that prior to 1950 you'd have 6v or 8v positive ground and after 1960 you'd have 12v negative ground.

Edit:

What determines the polarity is the regulator. The generator can have its polarization set either way by you.

Stan
There's No Such Thing As A Cheap Crawler!

Have: '58 JD 420c 5-roller w/62 inside manual blade
Have: '78 JD350C w/6310 outside manual blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Also Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

Jim B
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Re: 6volt gen to 12 volt gen

Post by Jim B » Thu Aug 09, 2018 5:41 pm

I would use negative ground unless there was a reason, like restoration to have positive ground (in which case you wouldn't be installing a 12 volt system). If the alternator was working before being knocked off; I would expect the tractor has been converted to negative ground as few alternators were/are positive ground. As Stan mentioned you need to be sure the regulator is the right one for the generator you have. Also as he noted some regulators are ground polarity specific, a generator can be polarized either way. A good parts store should be able to use the generator numbers to get the matching regulator for negative ground. Flash the generator once you get it all wired to set the polarity for certain (the contact points to use to flash the generator are different for Delco and Autolite).

If it was running when the alternator got knocked off, it would seem the coil and resistor must have been working. Is the resistor in the ignition wire ahead of the coil? On the coil is the wire from the resistor hooked to the + terminal and the distributor wire to the - terminal? If so it is set for negative ground. Did the coil and resistor get damaged when the alternator came off and need to be replaced, or are you just planning an upgrade? Some Delco systems used the external ballast resistor with the 12 volt coil, so it may or may not be a 6 volt coil. I would say if you are in doubt about the coil and resistor, get a new 12 volt coil with internal resistance and eliminate the ballast resistor.

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