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Subject: Front mount coil

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Bob E    Posted 05-10-2017 at 23:50:45 [URL] [DELETE]        [Reply] [Email]  
  • Front mount coil
  • I posted a couple weeks ago about my 1945 2N not running the best, well I did a compression test, new spark plugs, distributor cap, points, condenser, rotor, tested plug wires, cleaned carb and minor kit, cleaned sediment bowl, timed distributor. Problem was still lack of power on acceleration, some back firing, seemed to run better at full throttle then half. I had replaced coil a couple years ago with new one, but after fighting this lack of power for 3 weeks and missing engine, l had a coil from the used distributor assembly I bought at the salvage yard, the guy gave it to me, as a last resort I put it on and it ran the best It has in months. My question is am I alone with this issue on coils? It seems I need coils more often then spark plugs. Both tractors are front mount distributor, 6 volt originals. Thanks Bob E

    kylemorley    Posted 05-16-2017 at 09:32:18 [URL] [DELETE]        [Reply] [Email]  
  • Re: Front mount coil
  • If you do need yet another. coil, consider making or obtaining a round can coil conversion. Hotter spark, much more durable, and cheaper should it ever need replacement again (highly unlikely).

    Bruce (VA)    Posted 05-11-2017 at 08:59:04 [URL] [DELETE]        [Reply] [Email]  
  • Re: Front mount coil
  • Correlation does not imply causation.

    The fact that the tractor wasn't running well with one coil and now it does w/ another coil does not mean the first coil was defective.

    I have a coil on one of my N's that fits the description you gave; it came from a neighbor. He swore it was defective because his new coil got the tractor running. It's been on my tractor now for a few years.

    I've got 3 frontmount 8Ns. In the past 17 years, I've had 2 coil failures; one was stripped threads on an otherwise good coil & the other really was a failure. No spark when hot.

    Coil problems are difficult to diagnose. For starters, round coils are pretty robust & square coils arenít (because of the difference in insulation used), but neither one will hold up to a poorly done 12v conversion that allows too much current to the coil or leaving the key on (see tip # 38). Too much current creates heat which melts the insulation. Insufficient resistance in a 12v conversion will do the same thing. Rarely do coils just ďgo bad.Ē

    There are a few ways to see if a coil is bad, but itís not possible to determine if a coil is good w/o some expensive testing equipment. If you detect a dead short or high resistance in the coil w/ an ohm meter, itís bad. If itís cracked, itís bad. If a sidemount coil w/ battery voltage to the primary will not jump a ľĒ gap from the secondary wire to the block, itís bad. But, here is the hard part: even if you do not detect a short, even if it will produce a spark, even if itís not cracked, that doesnít mean the coil will work when itís hot & under a load. So, itís a process of elimination. If the tractor starts & runs fine for 30 minutes or an hour then cuts off & refuses to re-start, and you checked for spark at the plugs & it had no spark at all, AND you have the correct voltage at the coil thatís a good sign that you have a bad coil. Let it cool off, restart it & if you have a good spark, odds are itís a bad coil. But, even then, you might end up w/ a spare coil on the shelf!

    Bottom line.......coils do go bad, but I'll venture a guess that 75% of new N coils sold today are sold to folks who do not understand how to diagnose a poor spark problem or how a coil works. So, for those who donít know any better, in a no spark situation the first suspect is usually the coilÖÖand, more often than not, it isnít the problem.

    Or as one regular around here humorously suggested: "Well, it is like this...I don't know or really understand what that black thing does & I am suspicious of the unknown, so I think the problem is the black thing."

    " Problem was still lack of power on acceleration, some back firing, seemed to run better at full throttle then half."

    That's not a symptom of a coil problem.

    Put the "defective " coil back on the tractor & see if the problems reappear.

    And, if you are in the habit of leaving the key on, you will have a lot of coil problems.

    Bob E    Posted 05-11-2017 at 23:15:20 [URL] [DELETE]        [Reply] [Email]  
  • Re: Front mount coil
  • Just came from the field, the tractor ran great for the first 30 to 45 minutes, then there was some hesitation followed by lack of power at all RPM's. I was not able to pull the disc any more so headed back to the shop [NOT HAPPY], unhooked the disc and got on my 8N to try to get this job done, the 2N which is the tractor I am having trouble with shuts down and will not restart. I head to the field with the 8N and disc for about 2 hours. Come back to the shop and the 2N starts up with no problem. To recap on the 2N, I tried everything that I thought of and the only thing that made it run nice was when I changed the coil, I have had these tractors for several years and have a few spare parts to switch around. I am not a mechanic but am handy at most things and fix a wide variety of breakdowns. But this tractor has me baffled. Bob E

    Bruce (VA)    Posted 05-12-2017 at 07:34:08 [URL] [DELETE]        [Reply] [Email]  
  • Re: Front mount coil
  • There is a difference between what you said yesterday: " Problem was still lack of power on acceleration, some back firing, seemed to run better at full throttle then half." and what you said today: " the tractor ran great for the first 30 to 45 minutes, then there was some hesitation followed by lack of power at all RPM's"

    Maybe the difference is that I misunderstood you.

    This is what I suggested: " If the tractor starts & runs fine for 30 minutes or an hour then cuts off & refuses to re-start, and you checked for spark at the plugs & it had no spark at all, AND you have the correct voltage at the coil thatís a good sign that you have a bad coil. Let it cool off, restart it & if you have a good spark, odds are itís a bad coil. "

    Did you check for spark as soon as it stopped running?

    Yes, you could have a defective coil......you could also have a defective ignition switch too as steve va pointed out. (see tip # 50)

    Save the "defective coil". Next hot day when you feel like fooling w/ it, put it back on the tractor.


    Bob E    Posted 05-13-2017 at 00:25:49 [URL] [DELETE]        [Reply] [Email]  
  • Re: Front mount coil
  • The tractor acted up on two different times in the field, first time it would cut out and not run well when slowing down RPM's to turn around on the end of the field, cleaned screen sediment bowl, took carb off and cleaned and replaced gaskets etc, checked spark plug wires, points, plugs, cap, rotor and condenser were all replaced prior to this. I did a "restoration" of the tractor in 2010, all wiring was replaced with factory reproduction looms, ignition switch was new at that time. I adjusted the carb as instructed, but it would not rev up without hesitation and some backfiring or gurgling as I would call it. I put the used coil on and the tractor ran better right now, thought problem fixed till about 30-45 minutes of discing and then it hesitated and soon lost all power to perform. That is when I parked it and got the 8N to finish the discing. I work full time so not around the computer. Got home from work (Friday night) and the tractor started right up, went and hooked up the drag and company showed up so I did not get to the field, will give it a go on Saturday morning. Sorry I did not clarify the two separate problems. Bob E

    JMOR    Posted 05-12-2017 at 11:36:33 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Front mount coil
  • Another thing to keep in mind is that copper windings of coil increase resistance as coil/copper heats up, thus reducing current and spark energy as temperature increases. Actually, with no other outside influences, energy can fall to only 60% of cold start value as it reaches fully hot running temperature strictly due to resistance increase if coil windings.. Now, as a "for instance", let us say that various things are marginal in the engine, maybe mixture, compression, points, condenser, plugs, plug wires, state of battery charge, on & on, but spark is just good enough to make it run even with its problems, but as temperature increases, the spark drops from 100% (cold), to 90%, then 75% and finally drops below what it needs to be to keep the engine running fine. Whereas if all engine systems were perfect, it might "run fine" with a spark of 60%. Food for thought.

    steveVa    Posted 05-12-2017 at 02:08:13 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Front mount coil
  • Could be bad ignition switch. Could be diminished fuel flow to carb. Clean all fuel screens. Bypass ignition switch when it acts up. A single wire with allegator clips works good.

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