(800) 853-2651
SHOP NOW

350U LP - How do I tell if it has been con to neg grd?

A

AlanAtwood

Member
Well, I've had the tractor a week, and only had time to start it once. I got the owner's manual in and saw that it was originally a positive ground system. The old battery sitting on it when I picked it up was set up Neg ground, so that's the way I wired my spare truck battery in.

It appears to have the original 12v generator, and the coil was wired w/o a resistor. The + side of coil went to bat, and the neg side was wired to distributor.

Thanks,

Alan
 
I don"t understand your question. If it was 12V from the factory it certainly was negative ground, and you"ve told us that it still is.
 
All 350's came from factory with positive ground. The farmalls switched to 12 volt in mid stream but still positive ground. Diesels were 12 volt positive ground. I am not sure weather a factory LP gas was 12 volt or not but they were still positive ground. The 4 and 560's were the time frame for negative ground systems.
 
If I'm not mistaken, the - side of the coil should go to the distributor if the tractor is negative ground. Since yours does that, I would say it has been converted, which was your original question.
 
350"s and 450"s did not come negative ground from the factory, they were all positive ground, whether 6 volt or 12 volt. A lot of people converted them to negative ground, and they will start and run either way. But problems come in with charging systems and other stuff like instrumentation. His question about his "new" tractor is a valid one.
 
Hook up the battery as it was when you purchaced it.If the ampmeter reads to discharge(engine running),and you are sure it is charging,swap cables.The electricty can go either way,it doesnt care...If it still reads discharge,Then you have a chargeing problem to figure out.Another way to determine correct polarity is to turn on the lights.Simply see what the amp gauge says.That can be remedyed by simply reverseing the wires on the amp gauge.As was said,it was 6v pos ground when new.However,alot can be changed after 50+ years....
 
I stand corrected. I didn"t think even IH was silly enough to ship a positive-ground 12V nachine.

In any case he has the coil right way around for negative ground so if his generator is correctly polarized (which it is if it charges) he"s good to go.
 
The manual says 350LP and 350D were 12, and all others 6, at least in the IH variety.

We did have an old Ford Dexta deisel that was 12v pos grnd at least til we sold it sometime in the 80"s.
 
"Converting" a generator/regulator system from positive to negative ground is rather simple:

1. Swap the wires on the ammeter.
2. Swap the wires on the battery.
3. Swap the small wires on the coil.
4. Polarize the generator.

Everything is electromechanical. There are no solid state electronic components that will fizzle and burn if you hook them up backwards.

There are two possibilities here. Either the previous owner converted it to negative ground, or the previous owner was clueless and hooked up the battery negative ground.

Either way, you need to check the charging system out and make sure it's working. You can't just guess at what ground it is and hope it works afterward.
 
Thank you. I notice when it was running the ammeter was bouncing in the charge side of the dial but didn't seem to be doing much.

The old battery was dead dead dead, and since the tractor hadn't been started in years, I figure the generator needs polarizing. I had forgotten that part. Everything else seems to be in order for neg ground operation. 8)
 
Hopefully it's as simple as a repolarization. Next easiest will be to blindly replace the regulator.

There is a generator troubleshooting procedure written up by forum member "John T" that's really helpful in diagnosing these issues. I keep a copy of it in my I&T manual for the letter series tractors.
 
Lots of early 12v systems were pos gnd in that ear nothing silly about that only thing "silly" is those who didnt know about early stuff and how we got here.
 
You must log in or register to reply here.

Similar threads

K
changing from pos to neg
2
Replies
31
Views
731
kenbob
K
B
Farmall 656 Gas no spark, has power to coil
Replies
7
Views
435
wore out
wore out
D
12 volt Conversion WITH Magneto Farmall A HELP
2
Replies
21
Views
987
Jim Becker
J
W
Ferguson TE20 - converted to 12V with a generator?
Replies
9
Views
961
Jim.ME
J
G
convert 770 from pos ground to neg grd
Replies
4
Views
1K
Greg Raser
G
Tractor Parts Tractor Manuals

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.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top