EK Magnetos and Magnet Polarities
Portland fever is definitely in the air! Preparations for travel to the annual gathering are underway for engine enthusiasts from Australia, Holland, United Kingdom and of course across the U.S. For those of us on the Stationary Engine Mailing List, hosted by ATIS, the Antique Tractor Internet Service, it is a fantastic chance to meet all the folks we correspond with every day by e-mail.
It's a unique opportunity for List members, because instead of trying to describe problems and solutions with engines, we can show each other! And maybe, as we all look forward to seeing each other, that's why there hasn't been a lot of indepth discussion on the List for the past month. The questions raised have mostly been answered with a single e-mail or two, so there hasn't been much for me to pass on to the readers of GEM. - Helen
In the same way as people around the world tuck items away in the corners of engine sheds just because they look interesting and might be useful some day, I hoard old e-mails. The only query to the List I felt had the basis of a worthwhile subject was about an EK magneto. While the post in itself didn't provide a lot of information, it gave me the idea of searching through older e-mails in a bid to make up a definitive collection of magneto tips.
I have an EK magneto on an engine that appears to have been rebuilt. Everything inside looks new. The problem I have is a very weak spark - I can hardly feel it or see it with a spark tester. If I disconnect the wire and condenser from the inside and give it a few minutes and then reconnect, I get two good sparks and then it goes back to being weak. I have cleaned the points and tried a new condenser, but the results are the same. Any suggestions?
I've only touched on the subject of magnetos once before in these articles, and I assure you I have been most careful to use information only from those whom I consider to be the most knowledgeable in this area so that I can be confident of passing on the most reliable information.
The most suspect part of an original EK is the capacitor. They just don't last this long. If the magneto looks mechanically okay, the capacitor is the first part to consider. It's not possible to conclude a cap is good by testing it under conditions different from those in which it operates. Luckily, they're cheap enough so you can just put in a new one.
Here's a little tip that was passed on to me by Bill Young (an engine collector living in Japan). A weak area of the EK design is the movable point. It is grounded primarily through the bore in which it travels. If the bore becomes sloppy through wear, if dirt accumulates or if you become overly enthusiastic with the oilcan, resistance will be added to that part of the circuit. Minimal voltage loss in a magneto that is otherwise marginal can result in substantial degradation of the spark. The fix is to add a shunt wire from the point adjustment screw to the body of the magneto. The next question concerns broken magnets inside the magneto.
I finally got my upright Maytag running and discovered that the magnet is broken in half. She still wants to run. Can a guy weld and recharge those magnetos, or I am better off to find a replacement?
NO, NO, NO, NO! Don't weld your magnet! It will be ruined, and for several reasons.
First, the heat of welding will alter the properties and create a 'dead spot' in your magnet. Second, welding will spread apart the two halves of your magnet leaving an air gap inside.
Leave your magnet as it is and keep your eyes open for a replacement (I doubt you will find one). Check the magnets on later Johnson Utilimotors, they might be the same. FW magnetos for uprights were made by Quick-Action Magneto Co. At some point, they switched to Bosch. They look similar; you might get lucky.
Actually, unless the magnet is trying to fall off, it is probably best to leave it as it is. Two pieces of a broken magnet will be as good as a whole as long as they are in contact with each other and the core and are 'saturated.'
If one or both pieces are in danger of coming off, then it is best to only tack weld them on each side. Keep in mind that heat is the greatest killer of magnets. In order for a steel based magnet to be a magnet it must be very hard. Welding will destroy the temper in the steel and weaken the magnet. If appearance is your number-one consideration, then a replacement would be best.
Polarity should always be checked with a compass; do not depend on any markings, they can be - and many times are -wrong.
Use your compass only for comparison. Compasses that live close to magneto chargers can and do get reversed. Check your charger first, then the magnet to make sure they are opposites.
The note about polarity of the magnets is a crucial one, as is not relying on any markings found on the magnets.
I can't even begin to guess how many times people have asked why the 'NE' marking on the magnets isn't north (or northeast?). I think it is actually the logo of the magnet maker, 'Northern Electric.'
Don't trust the markings, and be sure to check your compass before charging your magnets. Mine gets repolarized about once a year if I am not careful. I never use my hiking compass to charge magnetos. I might get really lost someday!
On another note, chargers will reverse if you change the way they are connected to the power source. I don't recommend marking the poles of a charger, either; check with a compass every time.
North and south are not really important, opposite is what counts.
Okay, here's a question that gnaws at my guts - I've searched the Web, asked around, and nobody has been able to answer this in black-and-white.
Given: Magnets are marked N and S for the north and south poles. The compass is marked N and S for the north and south poles. The map is marked N and S for the north and south poles.
Observation: When I stand in the yard with my compass, the N points north.
Problem: Every elementary school student knows that magnets align themselves along opposite poles; north-south, but never north-north or south-south. Thus, my third grade education leads me to believe one of the following: The N on the compass is the South Pole, or when I'm facing north, I'm facing the magnetic South Pole of the Earth.
Question: Which is it? Is the N on the compass the South Pole, or was Peary really the first to reach the SOUTH Pole?
You've got it! Here's the way to remember: The needle on the compass is a 'North-Seeking' needle. That means the north point on the needle is actually charged south! This also leads in to why some magnets have marked poles yet are charged opposite the marks. Sometimes that means that the person who put the initial charge in was not paying attention. Other times it may have been an instruction to the assembly tech to 'put this pole on the north of the charger.'
As has been said before, a compass is used as a comparative instrument, not an absolute one. After all, which way is up, anyway?
Now that we've established the difference between north and south, there's the question of recharging magnets.
That is a capacitive discharge type of charger. That is how rare earth magnets are charged. In fact, you don't need such thick wire. You can use very thin wire, much smaller than is rated for such a large current. The capacitor dumps a huge slug of current through the windings for an instant. If you make your calculations right, then the wire won't melt. Kind of scary thinking that you could dump 200 amps through 18-gauge wire (or whatever the numbers come out to be), but that is how it is done.
I see how you can recharge horseshoe type magnets, but what happens if they are in a flywheel, like with Maytag or Briggs & Stratton engines? Do you have to remove them from the flywheel, or is it possible to charge the magnets in place? Also, how do you keep a keeper on the magnets while installing them?
Flywheel magnetos are usually charged with magnets in the flywheel, and it generally requires a set of specialized 'poll pieces' to make the connection to the charger.
Horseshoe magnets require a flat bar keeper, while flat bar magnets require a horseshoe shaped keeper. In either case you leave the keeper on the magnet until the magnet comes into contact with the core of the assembled magneto. Magnetos of any type can be charged as assembled units, or the magnets can be charged separately and moved to the magneto with a keeper. Most magneto guys use both methods of charging. Many of the old repair manuals give charging the magnetos as the last step before returning the magneto to service.
I hope this has clarified some of the mysteries of magnetos. If you can make it to the Portland show, then be sure to stop by the ATIS Stationary Engine List area to say hello. We have a big banner identifying us, lots of national and state flags, and plenty of unusual accents!
Engine enthusiast Helen French lives in Leicester, England.
Contact her via e-mail at: Helen@insulate.co.uk You can join the Stationary Engine List on the Internet at: www.atis.net