REFLECTION

A Brief Word


| August/September 1995



Case Eagle Bank

30/8/2

Richard McMunn

We don't have a large amount of correspondence this month, so this is our opportunity to include some related items that will hopefully be of interest.

Thousands of old engines are equipped with the Wico EK magneto. Technically, it's called a 'reciprocating inductor' magneto, since the armature opens both legs of the magnetic circuit, while the coils and magnets remain stationary. Various kinds of mechanical devices are used to operate the EK; all use a combination of pushrods and springs to provide a quick opening of the armature. The faster the break, the better the spark. Gummy or rusted parts materially retard the breaking action, and this results in poor sparking, and poor running of the engine.

The movable electrode on the Wico EK should open when the armature has moved 3/32 to ? inch from the magnet poles. This adjustment will give the hottest spark. Unless discharged accidentally, the magnets seldom need to be recharged. If this is required, it is not necessary to disassemble the magneto. All that is required is to take off the outer jacket, block the armature away from the magnet poles, and put it on the charger. Of course when recharging, unlike poles are placed adjacent to each other. There is nothing at all to be gained from reversing the polarity of the magnets. A cheap compass is all that's needed to determine the polarity of the magnets.

Wico EK magnetos seem to be prone to several ailments. One is that the original coils have a way of shorting out. Fortunately, replacement coils are available. The same holds true for condensers. The Wico EK uses one right hand and one left hand coil, so it's important to put them in their proper place. The points can also be troublesome, but this is usually caused by corrosion or possibly, oil on the points. Even the natural oil on your fingertips can cause problems. Oftentimes, a decent ohmmeter will show some resistance between the points, but there should be none; the meter should peg out to zero! An ohmmeter is one way of checking when the points open while adjusting the armature gap mentioned above.

Due to normal wear, the peg on the bottom of the Wico EK frame becomes worn, as does the matching hole in the armature. When this happens, the armature will not break both poles simultaneously; in other words, one breaks before the other. Under these circumstances, it's virtually impossible to get a good spark, or at least the best spark available from the EK. We recently proposed the idea of making a lathe fixture whereby the frame could be attached for the purpose of truing up the armature stud. The armature can then be bored out and bushed to fit the modified stud. Several readers have written to tell us that they have done exactly that, so chances are that someone can take care of this problem if you lack the machine shop to do it yourself.

Careful (and sometimes tedious) adjustment of the actuating springs is a necessity for certain trip mechanisms. Although several standard configurations are shown in the old catalog listings, it appears that the engine manufacturer usually built this part of the package. No doubt about it, some designs worked better than others.