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Subject: Charging system 51 8N 6V +Gnd

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Clarke    Posted 01-12-2020 at 12:48:59 [URL] [DELETE]        [Reply] [Email]  
  • Charging system 51 8N 6V +Gnd
  • What behavior (ammeter) do you expect if the field and ground wires from the generator to the regulator were connected backwards?

    Tim Daley(MI)    Posted 01-13-2020 at 08:24:55 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Charging system 51 8N 6V +Gnd
  • Ditto to what TOH said. Verify the wiring is all correct. Take your battery, generator, ammeter, switch, voltage regulator to a trusty, local shop -I'd use someone who knows old Fords - and he can test and/or rebuild if needed. Don't assume because you have a 6V battery it is wired correctly. Your '51 Generator should be the 3-Wire/2-Brush 20 AMP unit, B-Circuit design, with the angle (side) mount distributor, generator mounted on LH side, and NO Ballast Resistor. If you are burning up VR's, that is a big clue the wiring is all mucked up, not due to a bad VR.


    *PICTOGRAM courtesy of JMOR


    Tim Daley(MI)

    Clarke    Posted 01-15-2020 at 20:40:22 [URL] [DELETE]        [Reply] [Email]  
  • Re: Charging system 51 8N 6V +Gnd
  • Tim and Bob,

    I'm confused about the A-circuit/B-circuit distinction. I have just now gained access to the VR and its cover says "A-Circuit". It looks like the ones in Timís ďreplacement regĒ pics. The generator puts out enough to boil the battery over. And it looks like the ones I've seen illustrated as proper for the later 8Nís.

    If Iíve got a B-circuit generator with an A-circuit regulator, would that not explain the systemís inability to charge properly? But if I do have an A-circuit generator and regulator and the regulator has been adjusted improperly by the Alternator shop guy, maybe someone on here could tell me how to adjust

    I don't think I'm competent to follow the intricacies of the circuits and how they are supposed to function in principle. I would love to have a charging system that charges properly. I think I could bend the points closer or further and tighten-loosen the springs if I knew how to do this. (Being near 80 with Rheumatoid Arthritis, it is impossible for me to work inside the VR with the hood on.)

    Thanks for any further help.


    Clarke    Posted 01-13-2020 at 15:28:01 [URL] [DELETE]        [Reply] [Email]  
  • Re: Charging system 51 8N 6V +Gnd
  • Thanks much, Tim. Twenty or so years ago there was around here what you referred to as a trusty, local shop Ė someone who knows old Fords. Since then Iíve searched for such a knowledgeable person/shop without success. Iíve had to do everything myself, with the help of you guys.

    The wiring harness is fairly new and in good condition, which is very helpful in wiring correctly. My system is, as you said it should be: '51 Generator, the 3-Wire/2-Brush 20 AMP unit, B-Circuit design, with the angle (side) mount distributor, generator mounted on LH side, and NO Ballast Resistor. I donít think I have been burning up VRís, nor do I have evidence that the VR is bad, but the latest one (several years ago now) was purchased for me and then adjusted upon his machine by a fellow much younger than I whose shop title is ďStarters, ALTERNATORS, etc.Ē

    The period of a year or two when it charged as it should, long ago, was after I had done all the work on it myself, including replacing the brushes and bushings, cleaning the commutator, and buying and installing a new regulator. Whenever I have taken it to any local shop, no matter how highly recommended, it has come back unable to charge. My biggest problem is finding, in the archives, procedures and pictures that match the innards of my VR.

    Bob in Ks    Posted 01-13-2020 at 17:09:02 [URL] [DELETE]        [Reply] [Email]  
  • Re: Charging system 51 8N 6V +Gnd
  • "My system is, as you said it should be: '51 Generator, the 3-Wire/2-Brush 20 AMP unit, B-Circuit design"

    Isn't the 8N an A circuit generator/regulator? Jubilee and later were B circuit

    Clarke    Posted 01-14-2020 at 10:07:52 [URL] [DELETE]        [Reply] [Email]  
  • Re: Charging system 51 8N 6V +Gnd
  • Now I'm not so sure. I think I got this from the FO-4 manual: p.48 says that after 263843 the gen is 8N10001 and p.50 says "generators 8N10000B and 8N10001". I take these to say that 8N10001 would be a B. No?

    The How To's seem only to photocopy the polarization instructions you get with a regulator. Any help with adjusting the regulator to give a decent current when the battery goes down would be most appreciated.

    Bob in Ks    Posted 01-14-2020 at 11:58:30 [URL] [DELETE]        [Reply] [Email]  
  • Re: Charging system 51 8N 6V +Gnd
  • The B at the end of the part number indicates a revision in design or construction of the part.

    In an A circuit charging system the regulating resistor is between the output end of the field coil and ground. It grounds in the regulator case.

    In a B circuit charging system the regulating resistor is on input side of field coil and output side of coil is grounded to generator case.

    Dean    Posted 01-12-2020 at 12:59:14 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Charging system 51 8N 6V +Gnd
  • Such situation (not uncommon) would result in a "full field" condition.

    This would result in maximium output from a properly functioning generator regardless of battery condition or charge condition.

    The electrolyte would quickly boil away and the battery life would be significantly shortened even if water was periodically added to the battery.


    Clarke    Posted 01-12-2020 at 13:21:15 [URL] [DELETE]        [Reply] [Email]  
  • Re: Charging system 51 8N 6V +Gnd
  • Thanks much!

    I had taken it to a nearby tractor repair garage for engine and hydraulics overhaul. The guys who did this claimed they hadn't done anything to the charging system. In addition to the charging being completely unregulated, I saw some greenish-grey powder all over the glove box and down on the trans housing. (Iron sulfate?) At first I thought I was pleased, since the regulator had been adjusted by some other guys a while back, but had never shown any charging on the ammeter. I thought the battery was just very low and real old.

    I may ask for some help with my regulator, which actually regulated properly only for one period of time long ago. It's been a constant irritation.

    TheOldHokie    Posted 01-12-2020 at 18:57:32 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Charging system 51 8N 6V +Gnd
  • I'd check the wiring to make sure before I did anything I might regret.


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