20601 Old State Road Haybstadt, IN 47639
The question comes up quite frequently about WICO EK magneto
systems. The following discussion will be as it applies to small
size Hercules built engines. There are several things to consider.
While this is not a detailed account of the magneto itself, there
are a few basic things to keep in mind. The armature bushing should
not be loose on the shaft. When it brakes, both sides should pull
away from the magneto contacts at the same time. The points needs
to be clean and free from oil. The magnets need to have a strong
charge making it difficult to pull the armature away by hand.
Even though the magneto is in good shape, that does not
necessarily mean that it will operate well on the engine. There is
the matter of adjustment, wear and sluggishness of the tripping
mechanism. The screw and bushing in the armature should be tight
without any play. The slot in the tripping rocker arm should not be
worn excessively. It is important to have the proper springs in the
tripping mechanism. Any sloppiness of the side rod or the trip
finger mounting needs to be corrected.
The following information is taken from the operators manual
that will explain the whole adjustment process.
The numbers on Figures 15 and 16 will be used in the
instructions on adjusting Wico magnetos. Figure 15 is a cut of a
type P.R. showing the position of the trip finger No. 407 and
armature No. 100, just before the contact between armature No. 100
and the face of the cores No. 107 has been broken. Figure 16 is cut
of type E.K. showing position of the trip finger No. 407 and
armature No. 100 after the contact between armature No. 100 and the
face of the cores No. 107 has been broken, also at the point where
trip finger No. 407 trips off of rocker arm No. 412 causing
armature No. 100 to return to its original position.
Note–Type P.R. and type E.K. magnetos are alike except in size
and the location of spring No. 97. Therefore the instructions on
Wico magnetos will apply to both types.
Latch-off of Trip Finger
(See Figure 16)
The rocker arm (412) is provided with a screw (419) and locknut
for adjusting the ‘latch-off’ of the trip finger. This
screw must be set so that the latch (407) will slip off the lip of
the rocker arm just after the breaker points have been opened by
the downward movement of the armature.
If the screw is screwed OUT too far the breaker points will not
open and the magneto will not spark.
If the screw is screwed IN too far the trip finger will drive
the armature down too far and possibly break the return spring or
the parts that hold it.
This adjustment will be made originally by the engine builder
and should not require attention thereafter. It has nothing
whatever to do with the time of the spark.
If necessary, the adjustment can be made as follows:
Trip the armature (100) from its contact with the cores (107)
and insert a strip of metal 7/64‘ thick
between the armature and the face of the cores. Move the push rod
slowly until the latch of the trip finger reaches the rocker arm.
The edge of the latch should then just engage the edge of the lip
of the rocker arm, and the adjusting screw (419) should be bearing
on the top side of the latch (see Figure 16) so that the least
further movement of the push rod will cause the latch to slip off
the edge of the rocker arm.
If the latch does not engage the lip of the rocker arm when
armature is set as above, the adjusting screw should be screwed in
until the latch just engages. If the latch engages the lip of the
rocker arm too much (more than 1/32‘),
unscrew the adjusting screw to give the proper engagement.
Loosen the locknut on the adjusting screw (419) before
attempting to change adjustment and be sure to set it up tight
after the adjustment has been made. Remove the metal strip before
attempting to start the engine.
Adjustment of Breaker Points (See Figure
The breaker point contacts are perfectly adjusted at the
factory, and no readjustment will be required except when
installing new contacts, at which time proceed as follows:
The breaker point contacts (301) and (223) should just touch
when the armature (100) is 7/64‘ from the
cores (107). To adjust, trip the armature from its contact with the
cores, and insert a strip of metal 7/64‘
thick between the armature (100) and the face of the cores. Loosen
the nuts (302) on the breaker point stem (see Figure 18), and turn
the upper nut until the contact (223) just touches the contact
(301). Then set up the lower nut tight against the upper nut. As
soon as adjustment has been made, be sure to remove the strip that
you placed between armature and cores.
Latch and Latch Block Edges (See Figures 15 and
If the edge of the latch (407) becomes worn where it engages
latch block (5), a fresh edge can be obtained by clamping the latch
in a vise and pulling it out of the trip finger and giving it a
quarter turn before replacing it.
A fresh edge on the latch block (5) may be obtained by loosening
the latch block crew and giving the latch block a quarter turn
before replacing it. The screw is headed over at its outer end and
the heading should be filed off before attempting to loosen the
screw. Be sure to replace the lock washer and set screw up tight.
The latch-off screw (419) should be removed to get at the latch
block screw. After the latch block is replaced, the latch-off
adjustment should be made as described under