8N Wiring

I was given a 1949 8N to use if I could get it running. It had
a 12v conversion done. The wiring was a rat nest. I ordered
the 12v conversion wiring harness from here. I expected the
wires to be labeled. I was wrong. Anyone have a good
diagram?

Google pictograms by jmor

Thanks

(quoted from post at 21:13:02 06/01/23) Thanks

Click to expand...

be sure to get the correct version, as there are two different styles of 8N - front mount distributor, which features a strange distributor/square coil monster, or side mount, which looks like an normal old automotive setup.

the front mount diagrams are the ones with the words "resistor block" and "before sn 263844" on them.

a 49 would be a front mount, but years are often misidentified.

This post was edited by HFJ on 06/01/2023 at 06:18 pm.

Welcome aboard the wonderful world of FORD Tractors. Do you have any prior experience with tractors, in particular FORD TRACTORS? Be certain you have an 8N first - 9N and 2N's use different setups. Main differences: 9N/2N = 3-SPD Transmission & Draft Control only. 8N has a 4-SPD Transmission and addition of POSITION CONTROL. 9N/2N used a 1-Wire/3-Brush GENERATOR with the Roundcan Cutout. They also used a 1-Wire Starter Motor with NO Relay (Solenoid). The 8N Model introduced the 3-Wire/3-Brush ( later 2-Brush) GENERATOR and square Voltage Regulator. The 8N also introduced the 3-Wire Starter Motor WITH a RELAY (Solenoid). ALL N's with the front mount distributor used the Ballast Resistor and you need to use it whether using 6V or 12V. The later 8N with Angle Mount distributor never used the Ballast Resistor. It and all models after used a passive Junction Block Terminal Connector. In addition, any reason why you insist on using 12V? Both systems will work fine, and it's your tractor so do whatever you want, just be sure you know why. Many fellas can't figure our the 6V system, have non-starting issues due to incorrect wiring, the front mount distributor is a unique setup in itself, so they think a 12V setup will 'fix' that problem. As our late Sparkie Meister Dell used to say, ...if it won't start on 6V what makes you think it will on 12V...? FACT #1 is that 99.98% of all non-starting issues are due to incorrect wiring regardless if 6V or 12V. Before you do anything else, the biggest favor you can now do for yourself is to purchase copies of the ESSENTIAL MANAULS for your tractor. Forget serial numbers; they mean relatively nothing. As H mentioned, there are TWO styles of the 8N. The early 8N, 47-50 used the Front Mount Distributor, til s/n 263843 but as said, don't go by s/n's. The later 8N, 50-52, s/n 263844 and after, used the Angle (Side) Mount Distributor. ALL FORDS used the 6-VOLT, POSITIVE GROUND Electrical System til the diesel models came out in '58/'59. Ya hasta know how the OEM system worked B4 ya start switching around to 12V and if'N ya wanna be a FORD TRACTOR Owner. Gotta know how OEM systems work and how to repair yourself - the manuals have all that. A proper 12V conversion requires many changes to the original wiring. The GENERATOR and the VOLTAGE REGULATOR get removed from the circuit altogether and in their place a 12V ALTERNATOR is installed. The DELCO-REMY 10SI, 1-WIRE Unit is a proven reliable choice. Whether 6V or 12V, doesn't matter which, you must have a GEN or an ALT Fan Belt Tensioning Arm attached. Without proper fan belt tension, you will never charge the battery, and, the water pump will not function correctly which you could cause damage to the cooling system as well with overheating. Avoid the temptation to just start yanking off original parts willy nilly cuz they look old and buying new ones to replace with. True root cause problem solving is the most logical, correct to troubleshoot problems and fix. Test parts first. The wiring harness you bought must first be verified if it is correct for whichever dist you are using - Front or Side. First up is to take your battery to a local GEN/ALT shop and have it tested on their machine. The battery mist surain a full charge under load and if it tests bad, invest in a good brand like INTERSTATE, DEKA, EXIDE, or DURACELL for some. Bargain house brands like from tsc, wally-world, k-mart, et al, most always have poor life spans so open your wallet to the better brands. You won't be let down. Then with the battery disconnected, verify the entire wiring system and wire new harness correctly. You can't go by color codes, mainly because there was NEVER a 12V wiring diagram ever by FORD. Besides, Colors don't conduct electrons. Use you VOM set to CONTINUITY and never an idiot Test Light. A Test Light requires power and you don't want any power in the circuit when testing. Don't guess. Don't take shortcuts. One thing to consider with a 12V Conversion is which coil you are going to use. If you plan on using the original 6-VOLT Coil, you will need to buy and install an external, 1-OHM Resistor in the coil circuit to match the system. If you switch to 12V and invest in a verified 12V coil, you do not add the extra resistor. Also, lighting kits were always optional dealer options. Many were wired incorrectly if done by the owners. Disconnect lights when verifying wiring. Once you double and triple check wiring setup, and system is running properly, you can add your lights later. FWIW & FYI: Industry Standard part numbers for lights are: 6V Sealed Beam Headlights = 4019; 12V Sealed Beam headlights are p/n 4419. 6V Taillight Bulb is #63; 12V Taillight Bulb is #67. If you are switching over to 12V, be sure you swap out your lamps as if you leave the 6V lamps in, the second you apply 12V power you let out all the smoke and render it junk. SEE PICTOGRAMS by JMOR below.


WIRING PICTOGRAMS by JMOR & RELATED DOCUMENTS:


OEM 6V/POS GRN WIRING SKETCHES, FRONT MOUNT & SIDE MOUNT SHOWN.


12V WIRING SKETCHES - 6V & 12V SHOWN:

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



Tim Daley (MI)

I bought a 51 a year and a half ago that the seller had tried to install a conversion harness on and had made a huge mess of it. The JMOR diagrams made it a piece of cake to correct the mess.