magneto conversion

Discussion in 'Shop Talk' started by Runners, Jan 28, 2005.

  1. Runners

    Runners A real Quack!

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    I have a 1976 10kw generator with a Wisconsin engine (model THD, 16hp, twin cylinder, <100hrs total run time.)

    It has a weak set of magnets on the magneto, and rebuilding + remagnatizing the magneto is about $75 plus shipping.

    Does anyone know of a conversion to a CD or electronic ignition system? or some kit or plans I could just build myself? Both plugs fire together, on each stroke, no distributer is necessary, just a consistent, hot spark.
     
  2. JustinThyme

    JustinThyme Active Member

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    How is the gap ? Just a few thou will make a diffrence .
     

  3. ex mek

    ex mek Member

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    Most MAG type ignition has points AND a Condenser just like the pre electronic cars, points gap is critical so check it and condensers are cheap try a new one first , I have never heard of magnets dying , so i would discount that , and if the mag's windings have gone down there would be no spark at all.
    Mags dont like geting damp that will short them out , ( shove it in a LOW oven for ten minuites to dry it out ) and make sure the cam the points run on aint rusty , it grinds away the heel on the points and so closes the gap,
    As I say If its got a Condenser I would jump for that first .
     
  4. agmantoo

    agmantoo agmantoo Supporter

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  5. Runners

    Runners A real Quack!

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    Thanks for the suggestions, but I think I got them covered already..

    I have the option of having it rebuilt (all it needs is magnet recharging), but what a waste of money. For anyone that wants to persue rebuilding:

    http://www.mainelymagnetos.com/magnetos.html

    I believe the problem is weaken magnets, the condenser is not charging enough to produce enough reverse current through the coil... The points are set to .016. (probably should have mentioned it). Years ago, when magnetos were common, and rebuilt, the magnets were also recharged - the devices used a tube rectifier (Tungar Bulb) and a couple of big coils.

    An electronic, or CD ignition system would be my choice over a magneto w/points, condenser & coil. This might be beyond the scope of this forum, but if someone out there has done it, this is my preference - electronics for reliable starting & fuel effeciency via a hotter spark.

    I'm not adverse to grinding down the cam on the magneto or welding on a tab to work with a pickup sensor for a breakerless ignition - but, before I start to destroy this thing (and learn the hard way), does anyone know of a conversion kit from magneto to electronic / CD ignition?

    Bill
     
  6. daeve

    daeve Well-Known Member

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    If you are planning on going to electronic ignition anyway why not just add a coil (you already got the points and condenser) and battery. I believe you said the plugs both fire at the same time so one coil should get you going again. I've used the new style (transformer type) automotive electronic ignition coils to do this before with good results.

    As for the existing problem I have seen a few magnets go bad before. Sometimes you can recharge them a bit with another magnet just by putting it to the face of one to be recharged and leaving it a while. A neodebendium (sp?) or other high gauss rare earth type would be the type to try. Other than that a soft iron bar with a bunch of windings of copper wire hooked to a battery may also be used to recharge one a bit.

    Have you changed the condenser? I have seen a LOT more of them go bad than magnets. Sometimes even one that tests good (capacitance wise) will have enough leakage to cause the spark to be underpowered or nonexistent.

    Another thing to check is rust on both the iron around the magnet structure as well as on the magneto side. It tends to short out the magnet lines of force that make it all work and can cause the magnets to seem too weak to do the job.

    As a last shot... Replace the magnets. If nothing else drill a hole in the center of the existing magnet and insert a small cylindrical rare earth magnet with a bit of super glue to affix it. Should give you the same or greater output than a recharge ever would. Another possibility is remove the entire existing magnet and replace with one from a old hard drive head assembly. Dremel tool work for sure...

    Just sticking my 2 cents in. Keep us posted on your progress. Good luck!
     
  7. Runners

    Runners A real Quack!

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    Thanks daeve, short of shipping the thing out, I hadn't thought of the rare-earth magnet idea, that might work.

    This is the 3rd condenser and set of points - again, the 30 yr old engine has less than 100 hrs on it. When I had an inductive timing light on it, I could both see and hear every miss - really disgusting and frustrating! From what I can easily see, it's REAL clean, the coil is nice bright red, no rust anywhere internally and very little external surface rust (a patch here or there where the paint got nicked or scraped off).

    Just this darn ignition problem.
    Bill
     
  8. daeve

    daeve Well-Known Member

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    When you say this is the 3rd condenser and set of points, do you mean since this problem begin or that you have put in this engine in the last 30 years? :)

    Reason I am harping on this is that if the condenser is new old stock it could be bad out of the box. The electrolyte in them goes bad/dries out/leaks out after a few years and they loose capacitance. You can check them on a standard capacitance meter if you can find one. However if you have tried 3 and it is doing the same with all of them then I would certainly suspect another problem.

    If the magnet has enough stuff to pull the magneto (or other metal objects) to it firmly it should give you good spark providing all the other components are good.

    Have you checked the gap between flywheel and magneto?

    Quick and dirty way to adjust the gap: Turn the flywheel so the magnet is even with the center pole of the magneto, put a standard weight non-embossed business card between the flywheel and the magneto, loosen the screws on the magneto slightly and get it to snug up to the flywheel against the card, tighten the screws and turn the flywheel to remove the card. Rotate the flywheel slowly by hand to make sure everything clears then put it all back together and try it.

    May not be the proper way but seems to work on most small engines. Or the older ones anyway.

    Another thought just hit me. Are the points on this engine opened by riding directly on the lobe on the crank or is there a short metal plunger (?) riding in a hole in the crankcase that pushes the points? I had an engine one time that gave me fits running rough. Had a dry plunger (push rod, crank follower rod?) and it was binding in the hole enough that the spring on the points wasn't enough to overcome the friction. Shot of the old standby WD-40 to loosen and then white lube and no more problems.

    Good luck.
     
  9. John Hill

    John Hill Grand Master

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    I assume this is a flywheel type magneto? The magnets are mounted on a non-magnetic ring that is pressed into the rim of the flywheel?

    I had a Swedish outboard with a mag like that and the spark was very weak, someone finally noticed the ring had moved its position inside the flywheel so that the magnets were no longer passing the coil at the optimum time for the points to open.

    Just a thought.
     
  10. Runners

    Runners A real Quack!

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    Sorry to keep adding information, I guess I just assumed too much..

    Ok, this is a magneto like what was commonly found on older tractors. It is a gear driven unit, bolted near the flywheel. There is a gear between the flywheel and the magneto that drives the magneto. It looks sort of like a distributer with 2 spark plug leads. It has a "kill" switch on the side of it (just shorts it out), and a lead wire back to a "stop" switch (just shorts to ground).

    This is the 3rd set of points and condenser, all purchased NEW last summer, each becoming useless in just a few hours of use.

    The magneto has a built in "retard" system, commonly heard as a "klink-klink-klink" sound as the engine is being started. The retard is to aid in easier starts.

    These engines were commonly used on hay balers, cement mixers, generators - they are a 2 cylinder cast iron with an AL head. These were the work-horses for a lot of uses, and by no means "old junk" - even with minimal care, they will run a very long time. They incorporate a large oil sump for extended run times. I just got -LUCKY- ;) and found one as a 10kw genset with a transfer switch to boot! Even nicer is the unit was factory fitted for propane - a homesteader's dream. Even better, they had a second one - got and sold that one a couple of years ago (it had 47hrs on it, mine had 11 hrs on it).

    ... when I got the OK to remove it, I gladly hauled it - as fast as I could!

    Sooooo..... I got weak magnets - maybe I'll pull it apart this weekend if the weather is too miserable to work outside. That rare earth magnet idea sounds interesting.
     
  11. HermitJohn

    HermitJohn Well-Known Member

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    Look at this article: http://64.233.161.104/search?q=cach...+for+electronic+ignition&hl=en&client=firefox

    This is the html version, there is a downloadable pdf version (look for link at top of above page) which might have better version of diagram.

    Anyway although this says for one lung engine, since your engine has bolt on type magneto it should work. It uses the points as a switch and very small current actually passes them so they last forever without cleaning or regapping. Says he used the condenser but he also says it had no effect when he removed it. You would just use a normal automotive 12V ignition coil and circuit like previous poster showed you.

    There used to be kits for this type ignition back in the early seventies before car manufactures went to electronic ignition. If you look you might still find such a kit. These kits actually worked pretty good and points lasted indefinitely when ignition set up this way. With regular old point system, points had to be adjusted every 1500 to 2000 miles for optimum performance.
     
  12. Runners

    Runners A real Quack!

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    HermitJohn - I knew I saw that somewhere! (long time subscriber to HP)

    That oughta work, if it doesn't with both plugs, then I'll add a second coil...?

    I talked to RP last year over some battery issues - pretty smart fella, he's really got alot of experience on solar and batteries. Not that junk science stuff, but real documented, hard facts on this stuff.

    Anyone that's into alternative energy and not a subscriber to HomePower magazine is either trying to re-invent the wheel or can't stand the politics. (still tolerating..)

    Thanks,
    Bill
     
  13. HermitJohn

    HermitJohn Well-Known Member

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    Yes thinking about old tractor magnetos, yes you probably would need two coils since a magneto cap doesnt have the center tower for wire from coil. I also didnt describe this setup very well. It uses the points as a "sensor circuit" and then a transistor actual triggers the coil, thus not pitting/burning the points contact surfaces like in a regular point setup. The optical and magnetic systems the car companies came up with are little slicker but this system is very simular and works about as well in real world. Make sure the cam that open and close points is lubed or little fiber block thingy (or whatever is used in this instance to open/close points) will wear too fast and change point gap. Since this system doesnt need the condensor, remove it so magneto cant fire and pit the points. You just need the magneto to act as a "simple" point type distributor and open/close the points at proper time.
     
  14. HermitJohn

    HermitJohn Well-Known Member

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    Hmm, google search is turning up parts for an Autolite ignition distributor for a Wisconsin THD. Dont know if its interchangable with the magneto. I know my Allis WD has a distributor from later model. That way when I bought it. In manual shows it should have a magneto. So they are interchangable.

    Also might check this board concerning old stationary engines:

    http://www.ytmag.com/station/wwwboard1.html

    I did a search and quite a few posts concerning THD engines. Didnt go reading through them though. So you sure could post questions if you didnt find answer already posted.
     
  15. ex mek

    ex mek Member

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    When you say its used up 3 sets of points in a year , I would say the mag coils are short cirkiting and burning out the points ( dead internal winding insulation )
    the only answer is the electronc way or to fit a outside coil like someone mentioned allready .
     
  16. Runners

    Runners A real Quack!

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    An update on the magneto question...
    A generator repair guy (quickly becoming a friend), has convinced me the age of the unit and difficulty in finding parts is a bigger liability than I realized.

    After much agonizing - I'm replacing the 10kw generator with a 7-8 year old Generac 15kw unit. It's a 4 cylinder, 38 actual hours, has all the "bells and whistles" - but really rusty from being near the ocean. I'll have to rebuild the frame and engine mounts, clean it up quite a bit.

    The real plus is it's water cooled and an 1800 rpm unit. It has an outlet I can tap for a heat exchanger to recover some of the heated coolant to heat water - so I can take our water heater out of the Emergency Generator's Sub-panel.

    Unfortunately, the cleanup will take time (which I don't have, and this is ice storm season for Virginia), I'm busy with outside pond, underground piping/drainage work and poultry incubator construction, and it's time to find a helper or two.
    So, like someone suggested, I think I'll pull the old magnets off and replace them with some rare earth magnets to get it going again.

    I sure like the way those old units were built, strong and reliable... that Wisconsin engine was pretty noisy until I made a muffler out of an old refridgeration cylinder.
    Just hate to part with a unit with under 100 run hours because of it's age.

    Bill
     
  17. HermitJohn

    HermitJohn Well-Known Member

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    Alas I am finally learning about trouble of keeping old stuff going also. My 1957 MH444 tractor spun a bearing last fall. I have three options: spend more to rebuild engine than it will ever be worth without restoring it (assuming I can even find parts), or sell it as parts to collector for about what I have in it, or butcher it by replacing engine with automotive engine/transmission combination. It has other limitations/repairs needed and dry rotted 38inch rear tires so best just to remove loader and let it go as parts to a collector. Nice tractor for its time and served me well, but only around 6000 of them made so parts are a bitc_.
     
  18. Runners

    Runners A real Quack!

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    I'm realizing this is stuff for the farm exibition power/equipment shows, not something you should depend on to keep your business going. It's a disaster for us to lose electricity and our incubators get cold.

    We have them on 2 Ferrus UPSes, each backed up by over 700 amp hrs of battery banks - enough to smooth out the power bumps and minor outages.

    The really aggrivating thing is to just junk it and then a couple of years later, hear of some guy selling your "junk" on Ebay for a $1000. Like those old Dynaco tube stuff I had.... egads, I just threw it away when we moved and come to find out, the stuff is worth 3x the price of the best solid state stuff! :waa:

    My brother-in-law has an identicle unit sitting in his barn, less than 100 run time hours, transfer switch and all, never hooked it up. Probably has a weak magneto as well. Last time I needed points and condensers, I had to special order them - a week later, I had 3 spare sets of each. Just can't wait that long for parts when the chips are down.

    Alas.... the agony of a tinkerer and junk collector! Throwing away perfectly good junk!