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Subject: 8N won't start

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ron labbe    Posted 07-31-2017 at 17:18:25 [URL] [DELETE]        [Reply] [Email]  
  • 8N won't start
  • No spark with 8N (front mounted distributor)with new plugs. Gap points are OK.
    Automotive electrician suggested new condenser and checking fuse. Is there a fuse on 8Ns? Perhaps new coil needed.

    Bruce (VA)    Posted 07-31-2017 at 20:07:54 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N won't start
  • There is no fuse in the ignition circuit. And yes, it could be the condenser. It could also be a few other parts as well. But rather than guess at what part is bad, You'd be better served by systematically troubleshooting the problem.

    Assuming that the bushings & advance weights are ok (*see below), & that you have correct voltage to the coil (battery voltage with the points open and about half that with the points closed), the most common electrical failure (no spark, weak spark) points on the front mount are below. Check each one carefully. Even if you find a problem, check all 10:

    1. The insulator under the brass concave head screw & where the copper strip attaches. (it's fiber & will wear out; poke & prod w/ your meter leads to make sure it still works) If you need to replace the insulator, use a
    .250 x 3/8 nylon square nylon anchor nut available at most big box home stores.

    2. The pigtail at the bottom of the coil not making contact w/ the concave head brass screw inside the distributor. (With the coil on, the pigtail must firmly contact the brass screw. No contact = no spark) Check for continuity between the top of the coil and the pig tail; a 6 volt coil will be around 1 ohm & a 12 volt coil should be 2 to 3 ohms.

    3. The copper strip is broken or grounded to the plate. (look very carefully for cracks & breaks).

    4. The condenser wire grounding to the plate or side of the distributor.

    5. The tab on the bottom of the coil not making contact w/ the brass button on the cap. (With the cap on, the tab must firmly contact the brass button. No contact = no spark.) Check for continuity between the top of the coil and the tab; you should see about 6k ohms.

    6. Incorrect positioning of the spring clip on the plate causing the pigtail to ground. (the open part of the clip goes between 7 & 9 o'clock on the plate. That puts the straight part of the clip opposite of the timing screw at 3 o'clock)

    7. Incorrect seating of the coil on the distributor due to a loose bail or no gasket.(the coil must not move at all; if it does, replace the gasket or bail. Or stick some cardboard under the bail).

    8. Water/moisture inside the cap due to gasket failure or the absence of a gasket. (the cap AND coil have gaskets)

    9. Dirty/corroded/burned/incorrectly gapped or misaligned points. I use only Wells, Blue Streak or Echlin brand points (* *see below). If you are using quality points and cannot get the gap to open to .015, chances are you need to replace the bushings. If the shaft has any sideways movement AT ALL, the bushings must be replaced. (*** see below) If the tractor has been sitting unused for a few points, itís highly likely that the points are glazed. Dress them with brown paper or card stock. With the points closed, you should have continuity between them; high resistance means they are glazed.

    10. Burned rotor, cracked/carbon tracked cap.

    After find the problem & re-check the point gap, do a continuity check before you put the distributor back on the tractor. Before you start, make sure your meter/light works.

    With the distributor still off the tractor, follow these steps:

    1. Coil off, cap off, points open. One probe on the brass screw & the other on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere because the points are grounded.

    2. Coil off, cap off, points open. One probe on the brass screw & the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor....as the points open & close, you have continuity (closed) and lose it when they open.

    3. Put the coil on the distributor, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!

    4. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have no continuity!

    At this point, I just put the distributor, coil & cap all back on the tractor as a unit. The reason I do this is because it is real easy to get the cap or coil misaligned trying to put it back together, one piece at a time. The result is something gets broken or you get a 'no spark' problem.

    It's possible to put it back on wrong & break it. Look at the slot on the end of the cam shaft. Whatever angle it happens to be, turn the distributor tang to match it. Make sure you can tell the wide side from the narrow side on both the cam & distributor! (close counts). Place the distributor on the front of the engine, gently push it in place & slowly turn the distributor body until you feel the tang slip into the slot. Rotate the distributor body until the bolt holes line up. Hand tighten the two bolts until the distributor body is flush with the timing gear cover.

    * Unscrew the plate hold down screw & remove the C clip to get the plate out. Remove the shaft & weights. The weights should freely move.

    ** NAPA part numbers:

    . Points: FD-6769X or ECH CS35

    . Condenser: FD-71 or ECH FA200

    . Rotor: FD-104 or ECH FA 300

    . Cap: FD-126 or ECH FA 350

    ** Yesterday's Tractor kit:

    Premium Blue Streak points (A0NN12107ABS), rotor, condenser, and gauge Part
    No: APN12000ABSR

    ** Just8N's kit:

    Heavy-Duty Point Set, Condenser, Heavy-Duty Rotor, Heat Range Matched Spark Plugs. Packed 6 to Master Carton. Contains: 1-9N12107 Point Set, 1-AONN12300A Condenser, 1-9N12200 Rotor,1-9N12104 Gasket Kit,4-AL437 Spark
    Plug,1-015 Gauge, 1-025 Gauge.

    ** Distributor cam lube, Mac's Auto Parts:


    ** Distributor cam lube NAPA:


    *** There are three ways to replace the bushings in a front distributor:

    1. Buy new bushings (part numbers 9N12120 front & 18-12132 rear). Press out the old ones, press in the new ones and ream to fit. CAUTION: do not try this unless you have a press & know how to use it. If you break the base, a new one costs $130. If you bend the tower which holds the front bushing, a new plate will cost you $30. Resist the temptation to buy a new plate; most are pot metal and the threads will wallow out about the third time you change the points.

    2. Take the new bushings and distributor to your local machine shop.

    3. Send the distributor out for bushing replacement if you do not have a local machine shop

    Ron    Posted 08-01-2017 at 16:22:42 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N won't start
  • Thanks Bruce:

    It was number 3 - the copper strip was touching the retaining clip, probably as a result of my trying to get a 0.015" gap (the maximum with these points it seems). Also put the distributor, coil and cap back as a unit which I usually don't do; very tricky trying to get the right bolt on and the assembled unit passed the fan belt - next time I'll start with the left bolt. No wonder Ford went with a side- mounted distributor.

    Thanks to you and this forum

    Bruce (VA)    Posted 08-01-2017 at 19:33:03 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N won't start
  • You're welcome. Glad to help.

    Rustyal    Posted 08-01-2017 at 17:24:14 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N won't start
  • If you can only get .015 the cam block on the points is wore out.

    Rustyal    Posted 07-31-2017 at 19:41:02 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N won't start
  • You can check the insulator. In the distributor. And make sure your coil is not short to ground.

    Jack - Iowa    Posted 07-31-2017 at 17:35:11 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N won't start
  • Ron,

    Do you have a test light or a meter? If not, may be time to get one. You need to check the voltage at the terminal on the top of the coil.

    Is there voltage there? Is it the same as the full battery voltage? You can compare brilliance on a test light to determine this.

    If the voltage is there, does it move up and down as you turn the starter?

    If your ammeter is working, does it show discharge when you turn the key on? Does it swing up and back as you turn the starter?

    With this much information one can give you a much better idea of where to look.


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