8N Electrical System Determination

8NNoobie

New User
First off Hello! I am new to both this forum and Ford tractors in general. I just bought an 8N yesterday from the daughter of the previous owner. I was told that it had been running somewhat recently but she did not know much about it. Motor turns freely by hand.
I first want to get it turning over with the starter so I can check for spark. There is an alternator installed and some non-factory wiring. I took this as an indication that it most likely has been converted to 12V negative ground. When I went to hook up a battery I found that the lead running to the starter has the small negative ground terminal and the ground strap has the larger positive terminal. At this point I decided that I needed some help. I am assuming that the presence of the alternator means I have a 12V conversion, is there a way to tell? I pulled the coil but there is no voltage marking on it. Is there a way to tell if the alternator is a positive or negative ground?
Thanks in advance for any help.
 
You stand a about a 99% chance it is negative ground since positive ground alternators are not common. Know the brand of the alternator will tell use which it is
 
There are no markings on the alternator that I can find. Based on past automotive experience Im guessing that its a common GM one wire alternator.
 
(quoted from post at 21:36:07 08/29/22) First off Hello! I am new to both this forum and Ford tractors in general. I just bought an 8N yesterday from the daughter of the previous owner. I was told that it had been running somewhat recently but she did not know much about it. Motor turns freely by hand.
I first want to get it turning over with the starter so I can check for spark. There is an alternator installed and some non-factory wiring. I took this as an indication that it most likely has been converted to 12V negative ground. When I went to hook up a battery I found that the lead running to the starter has the small negative ground terminal and the ground strap has the larger positive terminal. At this point I decided that I needed some help. I am assuming that the presence of the alternator means I have a 12V conversion, is there a way to tell? I pulled the coil but there is no voltage marking on it. Is there a way to tell if the alternator is a positive or negative ground?
Thanks in advance for any help.
asy way to tell. 12v battery and a 12v bulb, such as tail or parking lamp. Connect one bulb connection to battery pos and other to alt output stud. Connect Neg batt terminal to alt housing. NO light means Neg gnd alt. If it lights, means POS gnd alt. Easyb pesey.
 
''Based on past automotive experience Im guessing that its a common GM one wire alternator.''

There's no such thing.

Outside of a few oddball applications GM didn't make a small frame (10SI or 12SI) ''one wire'' alternator.


The ''one wire alternators'' are aftermarket bastardizations of the GM design/chassis.

Unless there's an I.D. tag on yours as to exactly what is is, there's quite a range of what it could be.

The aftermarket sells them in your choice of (-) or (+)ground in a range of voltages from 6 to 12 to 24 to 36 and even 48 Volts.

As to yours, (unless the smoke has been previously let out) if the connections at the battery don't match the ''ground'' of the alternator there will be a huge spark if you try to connect the battery with reverse polarity of the alternator.
 
Was this meant to confuse the guy?
Both Noob and Old are correct.
If it looks like a [i:654c4848f0]'common GM one wire
alternator'[/i:654c4848f0] it probably is and [i:654c4848f0]'You
stand a about a 99% chance it is negative
ground since positive ground alternators
are not common.'[/i:654c4848f0]
 
Welcome To The Camp, Noobie-
Fist thing you need to do, if not already, is get copies of all The ESSENTIAL MANUALS for your 8N and read religiously B4 trying to start, run, or replace any parts
with new. You need to know if your tractor is indeed an 8N Model so don't base it on whatever the PO told you. Assume nothing. Read, listen, learn. The 9N & 2N had a
3-SPD trans and DRAFT CONTROL only -two of the biggest identifiers. The 8N had a 4-SPD Trans and also had POSITION CONTROL added. Is there a little lever under the RH
seat? That is the DRAFT and POSITION Control Lever. Also, does your tractor have the front mount distributor? Later 8N's switched to the side mount distributor. Know
the difference. Having a 12V battery, or a 6V battery for that matter, does NOT mean that the system is wired correctly for that setup. FACT TO REMEMBER: 99.98% of all
non-starting issues are due to incorrect wiring regardless if 6V or 12V. An 8N 6V/POS GRN system uses a 3-Wire/3 or 2 Brush GENERATOR, and a Voltage Regulator. 8N
Starter Motor is a 3-Wire unit and uses a SOLENOID. 9N/2N Models used a 1-Wire/3-Brush GEN and a Roundcan Cutout and a 1-Wire Starter Motor with NO Solenoid. ALL
12V/NEG GRN switch out jobs use a 1 or 3 wire Alternator, NO Cutout or VR, and both must have belt tensioner device attached. You can start with the manuals, read
posts and archives here, and listen to the guys here with experience. Then we will direct you to the correct wiring diagrams --- no N-Series tractor manual has a 12V
setup -they were never made 12V by FORD.


FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:
qI9P22kl.jpg


Tim Daley(MI)
 
Ultradog is right. Get a 12volt battery, negative ground and crank it over to see if you have spark. You will likely need to gain a good understanding of how the wiring should be. We will need to know if you have a front mount or sidemount distributor. Once that is known an accurate wiring diagram will be located. If it has not ran for a while get in fresh gas and turn it over to see if you have spark. It may fire right up.
 
Attached is an example of wiring diagram for 12volt negative ground front mount. You do need to determine what you have.
mvphoto96644.jpg
 
(quoted from post at 19:12:18 08/29/22)
asy way to tell. 12v battery and a 12v bulb, such as tail or parking lamp. Connect one bulb connection to battery pos and other to alt output stud. Connect Neg batt terminal to alt housing. NO light means Neg gnd alt. If it lights, means POS gnd alt. Easyb pesey.[/quote]

I like that tip JMOR.

Determines which way diode in alternator is pointing. Will remember that. Will work for other electrical stuff too.
 
(quoted from post at 12:23:16 08/30/22)
(quoted from post at 19:12:18 08/29/22)
asy way to tell. 12v battery and a 12v bulb, such as tail or parking lamp. Connect one bulb connection to battery pos and other to alt output stud. Connect Neg batt terminal to alt housing. NO light means Neg gnd alt. If it lights, means POS gnd alt. Easyb pesey.

I like that tip JMOR.

Determines which way diode in alternator is pointing. Will remember that. Will work for other electrical stuff too.[/quote]hank you! Looks like I am the only person to answer the question that the man asked, too.
 
If its 12 volt positive ground then its simply WRONG. Positive ground went they way of corn cobs and dinosaurs
 
(quoted from post at 19:39:37 08/30/22) If its 12 volt positive ground then its simply WRONG. Positive ground went they way of corn cobs and dinosaurs
allow your opinion, but it is not "wrong". It actually makes no difference, we could skip positive & negative and call it dynamo & earth. It is just a convention!
 
(quoted from post at 19:12:18 08/29/22) Easy way to tell. 12v battery and a 12v bulb, such as tail or parking lamp. Connect one bulb connection to battery pos and other to alt output stud. Connect Neg batt terminal to alt housing. NO light means Neg gnd alt. If it lights, means POS gnd alt. Easyb pesey.

Thank you this is exactly what I was looking for. I didn't think to check the diode direction. Turned out that it is negative ground. Ended up with no spark (to be expected) so next the distributor will come out for cleaning/points adjustment.

Also, thanks to everyone for the additional advice. I do have 4 manuals/books that I am going through. I haven't pulled the oil filter yet to find the serial number but I know I have a 8N (both brake pedals on right side)with a front mount distributor.
 
(quoted from post at 22:31:34 08/30/22)
(quoted from post at 19:12:18 08/29/22) Easy way to tell. 12v battery and a 12v bulb, such as tail or parking lamp. Connect one bulb connection to battery pos and other to alt output stud. Connect Neg batt terminal to alt housing. NO light means Neg gnd alt. If it lights, means POS gnd alt. Easyb pesey.

Thank you this is exactly what I was looking for. I didn't think to check the diode direction. Turned out that it is negative ground. Ended up with no spark (to be expected) so next the distributor will come out for cleaning/points adjustment.

Also, thanks to everyone for the additional advice. I do have 4 manuals/books that I am going through. I haven't pulled the oil filter yet to find the serial number but I know I have a 8N (both brake pedals on right side)with a front mount distributor.
ou are very welcome. Sorry you had to wade thru the chaff to get to your answer.
 
(quoted from post at 19:31:34 08/30/22)
(quoted from post at 19:12:18 08/29/22) Easy way to tell. 12v battery and a 12v bulb, such as tail or parking lamp. Connect one bulb connection to battery pos and other to alt output stud. Connect Neg batt terminal to alt housing. NO light means Neg gnd alt. If it lights, means POS gnd alt. Easyb pesey.

Thank you this is exactly what I was looking for. I didn't think to check the diode direction. Turned out that it is negative ground. Ended up with no spark (to be expected) so next the distributor will come out for cleaning/points adjustment.

Also, thanks to everyone for the additional advice. I do have 4 manuals/books that I am going through. I haven't pulled the oil filter yet to find the serial number but I know I have a 8N (both brake pedals on right side)with a front mount distributor.


8nNoobie
Glade you found out what voltage it is, when and if you rewire it be sure to check JMOR's wiring diagrams. But just because it has both brakes on the right side, it can still be an 9n or 2n, they made a conversion for the brakes. I have a 47 2n with both brakes on the right. Do you have a 3 speed trans or 4 speed? What does the bolt patterns on the front and rear wheels look like:

That said, a front mount 8n, 2n and 9n dist will use the same
distributor and parts and the point gap will be the same.

Trouttman
 
It has a 4 speed transmission it also has the smaller bolt pattern on the wheels.

There is with an auxiliary transmission. I haven t research the auxiliary yet but based on the detents believe it to be an under drive and overdrive model.
 
(quoted from post at 16:39:37 08/30/22) If its 12 volt positive ground then its simply WRONG. Positive ground went they way of corn cobs and dinosaurs

My 82 year old TyranaFordus Rex still has the electrons flow to the (+) ground.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top