Ford 8N No Spark

TylerAnd

New User
I have what I believe is a Ford 8N, but it is all gray in color so it could be a 2N. I pulled tractor out of the garage the other day and let it idle to warm up
it?s very cold in our area. Tractor started cutting out after running for awhile, then it died. Tried starting had no spark, I noticed wire from coil to side of
distributor melted a bit on the exhaust manifold. So I replaced that wire and still did not have any spark. Went to tractor supply and bought a side mount
coil with + and - on it that says will work for 6v without a resistor or 12 volts with a resistor on the box. This tractor has a 6 volt system and I believe it
should have positive ground but at the time I?m not 100% sure it was set up that way. With it set up at positive ground, i have the + on the coil going to
the distributor. I tried starting it no spark, if I take the distributor cap off and touch the points with screwdriver I do not get any spark with the key on. I?m
really stumped on this I?m not experienced with 6v positive ground systems I?m thinking I got something simple messed up but I?m also not sure if how
the generator is polarized has something to do with it either? Any help much appreciated. Thank you.
 
Trying to ID a tractor by it's color isn't a good idea. From your description of the coil, it sounds like you have an 8N, mid-1950 or later w the side ( round) coil.

Checking for voltage w/ a screwdriver or a light is not going to tell you much. If you don't have a strong battery w/ 6.35 volts, you will get a weak spark. At 6.00 volts, you get no spark.

Time to get a multimeter and an adjustable gap spark checker.

Generator polarization has nothing to do w/ your problem. The generator is in the charging circuit, not the ignition circuit.


Confirm that you have voltage to the coil. Battery voltage, points open. About half that if the points are closed.

If you do not have at least 6.22 volts, charge the battery.

Do you have battery voltage across the points when they are open? (with the points open, put one probe on one side of the points & the other probe on the opposite side of the points) Verify the gap on the points at .025. Then, dress the points by running a piece of card stock or brown paper bag through them. New points sometimes have an anti-corrosive dielectric coating on them & old points can corrode or pick up grease from a dirty feeler gauge or excessive cam lubricant. (I always spray my feeler gauge blade off w/ contact cleaner.) Make sure you have voltage across the points, as in past the insulator on the side of the distributor. That is a very common failure point on sidemounts, along w/ the attached copper strip. It's hard to find a short there because it is usually an intermittent . So 'wiggle' the insulator & the copper strip a bit when you are doing your checking. If you find the short there, the Master Parts catalog lists everything you need on page 154. You can make the strip and you could also make the insulators as well. But, somethings are just easier & in the long run cheaper to buy. Get the strip, 12209, screw 350032-S, 12233 bushing & 12234 insulator & just replace it all.


If you just replaced the rotor & lost spark, put the old one back in. Insure that the rotor fits firmly on the shaft & that the little clip is there. Make sure the distributor cap is not cracked, doesn?t have gouges in it from the rotor or brass shavings & doesn't have carbon tracks. Check continuity on the secondary coil wire. Make sure it is firmly seated in both the cap & the coil. Next, remove the secondary coil wire from the center of the distributor cap, turn the key on & crank the engine while holding the end of the wire 1/4" from a rust & paint free spot on the engine. You should see & hear a nice blue/white spark. If not, you have a bad coil or condenser. Just put the old condenser back in to eliminate that as a possibility.





Post back w/ results; I'll be interested in what the problem was.
75 Tips
 
First, open the door where the battery is. If it has three caps for water, it is a 6 volt battery. If it has those two covers that cap off 6 wells for water it is a 12 volt battery. Second, If the Positive (+) post is wired to the tractor frame somewhere it is a positive ground system. Otherwise it's a negative ground.
Third, get a volt meter and with the ignition key on, start tracing battery from one side of the switch through it and to one side of the coil. With the points open, you should see battery through the coil and to the terminal on the side of the distributor. With the points closed that battery should be reduced quite a bit. If not, try running a piece of brown paper bag across the point contacts. Let us know the results. By the way, if it is a positive ground then the + side of the coil should be wired to the distributor, but it will run either way.
 
Welcome to the forum! Don't let the 6V + ground worry you.
As others have said, check for power at the coil.
Since it was running and died, you may have lost power there.
The key switch in these tractors are a weak spot and it may be as
simple as the vibration from running caused it to lose contact inside.
We won't know that until you track it down, but it should be pretty
straight forward to find if you follow the voltage from where it's
good until where you lose it. Or vice versa.
 
Thank you for helping, I have 6.23 volts at the battery and the wire going to the - side of coil I?m getting 5.88 volts
 

cvphoto5291.jpg
 
Your battery voltage is fine.

Bump the starter until the points are fully open. Then, measure the voltage across the open points as I suggested. ( and check the gap)

See that red wire inside of the distributor? That's clearly not OEM and is the likely source of your problem as I said in my previous post.
75 Tips
 
So you mentioned that insulator in your previous post. The wire coming down from the positive side of coil to the side of the distributor goes to the screw that has that insulator and also connects to the red wire. I take it that those wires should not be grounded(not touching distributor hence the insulator)? Sorry if that?s a dumb question because then it would be shorting out there if I am correct?
 
Timberland, I apologize for my earlier response about checking to see if you had a 6 or 12 volt battery. I misread your original post and thought you were not only confused about the polarity but the voltage of your tractor. Have you found anything yet?
 
All 9N & 2N's had a 3-SPD trans, front mount distributor, no position control, and painted Ford Dark Grey. The 8N Model used the front mount til mid-1950 then changed to the angle(side) mount, had Position Control, and a 4-spd. trans. However, like Bruce said, never use color as an identifier. Don't guess, get the Essential Manuals. OEM FORD vehicles were all 6V/POS GRN, not just tractors. You need the manuals and JMOR's Wiring Pictograms and 75 Tips by Bruce to learn all you can about your N. Incorrect wiring is main cause of non-running/non-starting. A melted wire suggest you may have a rats nest and it could have shorted. A correct OEM-style wiring harness will never cause a melted wire unless not set properly.

FORD 8N TRACTOR WIRING DIAGRAMS:
PRIOR TO S/N 8N-263844:
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AFTER S/N 8N-263844:
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FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:
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CORRECT FORD 8N ELECTRICAL SYSTEMS - 6V & 12V:
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*PICTOGRAM courtesy of JMOR


Tim Daley(MI)
 
Thank you for your help, It is a 8n and it turned out to be shorting out at the insulator on the side of distributor.
 

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