New 8n Owner - Question about alternator wiring

Hey all, Just bought an 8n and am clueless on a lot of it. My battery kept dying as I was working and my neighbor told me my alternator isn't hooked up. He said I need a Delco pigtail for the alternator. Question is, I know the positive goes to my battery positive, where does my negative go? Thanks.

Sorry guys, here's a picture.

[/img]https://photos.app.goo.gl/kgtUyat9YoScWtb27

Were it new to me I would take that battery and alt to a parts house and have them
tested. Then I would google jmores wiring diagrams and bruces 75 tips. Print them out if
possible, keep them handy. Get the manuals suggested in the tips and welcome to the
world of Ford N addiction!!! Rusty

Those alternators are usually self grounding, usually no need for a ground, but there should be a threaded boss on the rear face of the alternator that a ground can be installed. The Delco plug goes in the small port on the side of the alternator and can be bought at a parts store. If I remember correctly #1 goes to a 12. Volt pos switched source and #2 goes to the battery pos, but most people run it to the power out stud on the back of alternator. The #1 wire will need a diode installed if you run it to the ignition switch, to keep power from back feeding and killing the battery. There are a lot of wiring diagrams available if you google 8n Delco alternator. Good luck.

There should be a 1 and a 2 stamped on the case window where the 2 wire Delco plug is. It may be hard to read, but most I have seen have the numbers stamped.

On those alternators that use a one-wire regulator inside, those two spade lugs need no connection....only the single stud on the rear is used. Measure battery voltage before starting and again at speed to determine if alternator has output. Voltage at speed should be a volt or so higher than before start voltage.

(quoted from post at 15:50:04 10/09/18) On those alternators that use a one-wire regulator inside, those two spade lugs need no connection....only the single stud on the rear is used. Measure battery voltage before starting and again at speed to determine if alternator has output. Voltage at speed should be a volt or so higher than before start voltage.

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Thank you all for your input. I've read the 75 tips. I'll check out the wiring diagrams.

So you're saying the wiring is correct, and that my alternator might be bad? Thanks!

So you're saying the wiring is correct, and that my alternator might be bad? Thanks![/quote]o, I didn't say that. I did say that 'if' it is one of those one-wire alternators, there is no need for connection to those 2 spade terminals. What I didn't say is that 'if' it is NOT a one-wire alternator, then it does need to have those 2 connections. You can't just look at the exterior of the alternator and determine whether it is one-wire type or not. Another thing I did say is that you may determine whether it is charging (as wired) by measuring battery voltage before starting and comparing that to battery voltage when running at speed. I also did not say that 'if' it is NOT a one-wire , but rather a three-wire type, that when running at speed, you can temporarily jumper those 2 spade lugs to the BATT stud and see it begin to charge. If this makes it charge, then you have a good alternator that needs additional wiring.






'

Gotcha-
I thought you could tell it was a one wire by looking at it or the model number. How do you tell if it's a one wire or 3 wire alternator? Will check the voltage before anything else. Thanks again.

(quoted from post at 10:32:52 10/10/18) Gotcha-
I thought you could tell it was a one wire by looking at it or the model number. How do you tell if it's a one wire or 3 wire alternator? Will check the voltage before anything else. Thanks again.

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ny rebuilder or any individual (I have done it) can open up the alternator and re-place a factory 3-wire VR with a one-wire VR and close it up and there will be no visible difference from the outside. Any numbers cast into or stamped onto the alternator are the same ones it had when originally manufactured in the '70's on my now one-wire alternator.......only I know.

STOP before you do damage to you or your new tractor. Realize that 99.98% of all no-starting/non-running issues are due to poor, incorrect wiring jobs whether if 6V or 12V, but most all are due to someone attempting a 12V switch over job who has no clue what they are doing. If you don?t already have the essential manuals, and especially if you are new to Ford Tractors, it is a good idea to get them. You?ll need to know if your tractor has a front mount distributor (used from ?47 thru early ?50) or the angle mount distributor; if the electrical system is still OEM 6V/POS GRN or has been switched over to 12V/NEG GRN, but either way it must be wired correctly in order to start and function correctly. The original 8N Operator?s Manual, the I&T F-04 Manual, and the ?39-?53 MPC (Master Parts Catalogue) are valuable tools to have in your shop, coffee table, and bedside stand. Read them religiously. In addition, go to the other Ford N-Series tractor web site, *N* - *T* - *C* and under the HOW-TO's forum/ELECTRICAL, you'll find "WIRING PICTOGRAMS BY JMOR" for FREE download. JMOR compiled a very good document of all the correct ways to wire these old N's whether 6V or 12V. Your battery isn't charging either because it is old and won't sustain a charge or it is wired all wrong, or both. Going by what someone says is foolish. Get a document to follow so you know for sure what you are doing. Your local starter shop can bench test the battery and the alternator for free, usually. Wiring a 12V switch over job depends on if you have the OEM Front Mount Distributor or the Angle (Side) Mount unit. You may or may not have a faulty alternator, but my money is on the wiring system being all mucked up.

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

Tim *PloughNman* Daley(MI)