Ford 8n

roserick1@aol.com · Nov 6, 2022

My 1951 8n has an alternator but a 6 volt battery, side mount distributor. Is it a 6 volt or 12 volt system, trying to install new headlights and don't know what to buy. It also has a negative ground.

This post was edited by [email protected] on 11/06/2022 at 01:34 pm.

old · Nov 6, 2022

They do make 6 volt alternators but there not common. I'd look it over real good and see if there is a tag or other marking which should tell you what it is

MN valley man · Nov 6, 2022

They do make 6 volt alternators for older vehicles such as my model A Ford, but they are rare. If you have
one of these they will be positive ground, so polarization is important to watch.

roserick1@aol.com · Nov 6, 2022

(quoted from post at 01:54:25 11/07/22) They do make 6 volt alternators for older vehicles such as my model A Ford, but they are rare. If you have
one of these they will be positive ground, so polarization is important to watch.

I have a negative ground. Will a 6 volt battery work in a 12 volt system?

roserick1@aol.com · Nov 6, 2022

Cant find any tags, Im stumped...

old · Nov 6, 2022

If it is a 12 volt alternator the battery will over charge and could even explode if you ran it very long that way. Best way to be sure is start it up and see what the voltage is across the battery terminal when it is running. If around 7 volts it is a 6 volt alternator if around 13-14 volts it is a 12 volt alternator

Welding man · Nov 6, 2022

We build them all the time, I have 3 in use on my tractors now. There is no way to tell them from a 12 volt unless you break out the voltmeter.

old · Nov 6, 2022

It is as simple as starting it up and using a volt meter to see how many volt are measured across the battery terminals can't get any easier then that

tractorguy2 · Nov 6, 2022

I put a six volt negative ground alternator on a 51 8n several years back.

J Hamilton · Nov 6, 2022

6 volt alternators can be either pos or neg ground depending how they are set up. Some of my tractors have pos ground and some are neg ground all 6 volt with alternators

wore out · Nov 6, 2022

(quoted from post at 14:54:25 11/06/22) They do make 6 volt alternators for older vehicles such as my model A Ford, but they are rare. If you have
one of these they will be positive ground, so polarization is important to watch.

6 Volt alternators are readily available in EITHER ground polarity, your generalized statement does not always hold true.

This post was edited by wore out on 11/06/2022 at 05:00 pm.

old · Nov 6, 2022

I believe what I told him is the easiest way to know for sure if it is 6 or 12 volts

hd6gtom · Nov 6, 2022

If you don't have a volt meter or unsure how to read it, pull it
off and take it to a place that tests alternators. They will be
able to tell anything you need to know.

used red MN · Nov 6, 2022

How long you had the tractor? Has it started an ran
more than a couple weeks and not required an
additional charge to the battery because it will not
start? If it did and the battery had 3 caps it is a 6 volt.
Basically a 12 volt alternator connected to a 6 volt
battery will possibly cause the battery to explode. The
alternator will likely over heat as well. As said a
voltmeter is the final word. If you have not had the
tractor long it is possible it is a 12 volt alternator
mounted on the tractor but not connected properly to
charge. If this is the case the alternator just spins
along doing nothing.

Ford 8n

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