Tip #1 - Wico Coil Replacement
- Wico Coil Replacement
deteriorated Wico flywheel magneto coils with common Johnson/Evinrude/Bombardier
(referred below as OMC) replacement parts.
made from the early 1950’s to mid 1960’s have close
to a 100% failure rate for the original magneto coils. This is often
due to the plastic insulating the coil being unstable and shrinking
with age. The force of the shrinking plastic, moisture intrusion
or other issues will cause the windings to short and the magneto
will not produce spark. Even if a cracked coil works on the bench,
it will almost certainly fail with use out in the field.
coils for OMC, Repco and Bendix magnetos are readily available but
Wico coils have been difficult to find and cost prohibitive when
they do turn up, (and the value of many old outboards do not warrant
a $60-$80 investment in coils). Inexpensive replacement coils for
OMC magnetos, (O.E. part # 582995 or Sierra# 18-5181), can be used
to repair Wico coils fitting a 7/16” diameter
laminate. (The laminate is the steel "E"
shaped part the winding/coil fit over - the center spindle must
be 7/16" x 7/16" in size.) The repair is quite easy and
both coils can be replaced in about an hour.
by removing the flywheel and stator/magneto plate from your outboard.
The example below (illus #1), is from a ‘53 Firestone 5hp
produced by Scott-Atwater. Note the large chunks of plastic missing
around the coils!
#1 Deteriorated Wico Magneto from a 1953 Firestone
the magneto; take note of how each coil is wired to each set
of points & capacitor and determine which coil fires the
top and which fires the bottom cylinder. (Use of a Sharpie marker
to note these details on the magneto plate is a good way to
avoid any confusion later.)
is also a good time to check the wires, test the capacitors
and clean the points – replace any components that do
not check out. The original Wico coil was matched to X5463 capacitors
rated at .16 to .20 microfarads. Since OMC coils call for capacitors,
(OMC part #580321), rated at .18 to .22 microfarads, there should
not be a problem using the original Wico capacitors with the
OMC coil. (On motors used many hours, check the points for pitting
since this will indicate if the capacitors are a good match.
For hobbyists who only put a few hours on their motors each
season it is unlikely the points will ever become worn due to
the 2 microfarad difference. )
keep things straight, replace one coil at a time. In Illus #2
below note the plug wire for the other cylinder under the coil
being removed – on reassembly it will be re-routed in
back of the new coil for space reasons.
#2 Remove Bad coil – note other
plug wire underneath
#3 Note small tab bent down so coil
can be removed
The original Wico laminate will need to be reused. Remove the
ground wire from the screw into the laminate and gently bend down
the small metal tab that holds the coil on the center laminate.
(see illus #3) Using a press or puller, push the laminate out
of the coil. (See Illus #4) The use of ¼”-20 “farm
nuts” (the square ones) stacked and held together with a
lopped off screw, make a 7/16” spacer to push the laminate
out of the coil. A little penetrating oil here won’t hurt
anything and could make sliding the laminate out easier.
# 4 . Use a small press to push the
#5 . New coil ready to go on old Wico
Once the coil is off, clean any rust or goop off the laminate.
Now do the same steps to remove the OMC coil from its laminate,
taking care not to damage the coil. Don’t forget to bend
down the small tab that holds the OMC coil on – in this
case don’t worry if you break it, you will not be re-using
the OMC laminate. (NOTE: As of 2009 many of the aftermarket OMC coils no longer use the small metal tab. They have 2 or 3 small dimples into the plastic at the end of the center laminate. I use an X-acto knife to remove the dimple next to the laminate, then remove the coil in the regular way.) An OMC coil from a parts motor was used for
this project – it easily slid off the laminate by hand.
FYI, if using re-cycled parts, be sure to test them and ascertain
they are in working condition before installation.
# 6 . Repaired coil ready to mount
#7 . OMC
coil & original Wico laminate in
the magneto plate
Slide the OMC coil onto the Wico laminate; it should go on by
hand without force (see illus #6). Attach the ground wire to the
laminate using the original screw and bend the tab up to hold
the coil onto the laminate. Now simply attach the plug wire and
install the coil/laminate assembly into the magneto plate. Remember
on this side we needed to route the other plug wire (as seen in
Illus #2) in back if the new coil since it will no longer fit
underneath as with the original Wico coil. (see Illus #7 - wire
is just visible on the right of the new coil)
OMC coils have a molded plastic protrusion where the spark plug
wire goes into the coil – this is tight against the side
of the magneto plate but will fit. (For this application the plug
wire needs to make a 90 degree bend to exit bottom of the magneto
plate - even though the original wire was serviceable a new Packard
440 wire core ignition cable was used since it more easily made
the sharp turn.) Lastly hook up the primary lead to the capacitor
and now you are ready to move on to the second coil.
the second coil is the same procedure as the first only without
the worry of re-routing the other plug wire. Once completed, remount
the magneto plate and set the points to the proper specification
(.020 on this motor). Replace the flywheel and check for binding
of the laminate heels on the magnet or counterweight. (Unlike
OMC coils, there is not really any provision for adjustment so
this should not be a problem.) Rope it over to check the spark,
there should be a nice healthy blue flash!
motor with this magneto repair has been run several hours and
performs very well, starting easily and idling nicely. One additional
note; after a few hours of use it was found that the original
spec Champion H-10J plugs appeared to be too hot, H-8J (now called
H8C) have been substituted in an attempt to remedy this.
EDIT 7/12: Here are a few photos of other substitutions done using the OMC Universal magneto coils. The OMC coils have provided fixes for Wico, Phaelon, Eisemann and other coils that are hard to get or NLA:
1956 Elgin 5.5hp used OMC condensers too! (Click on the image for larger size)
|1926 Lockwood 62T opposed twin - 2 coils on one laminate - photo courtesy of Jim M. (Click on the image for larger size)
About this Article
outboard that gave me the idea for this repair was a 1953
Firestone 5hp 10-A-73 (made by Scott-Atwater for Firestone
Tire & Rubber stores). I picked it up as part of a package
deal with 4 other outboards and figured it could be sold or
swapped to another hobbiest. Despite
the Firestone's nice original condition and being 100% complete,
no takers could be found for
$30 (obo) at
any of the AOMCI meets I attended. Frankly,
I never used to be a huge fan of this era Scotts but decided it was a shame
the little motor could not find a loving home. One rainy day,
with all my other chores completed, I decided to tear into
Firestone had excellent compression and the gears functioned,
(a weak spot on this era Scotts). As the tank and fuel system
were in the process of cleaning, I removed the flywheel to find
a mess like the one pictured here. I could not with good conscious
pay the $35 each for new coils for a motor that even $30 was
too high an asking price! I do not lay claim to be the first
to make this swap since I know that outboard tinkerers have
use OMC coils on just about every type of motor there is, however,
on this project, the idea came to me as I worked.
is always a good feeling to bring a motor back from the dead
and in this case the investment (other than my time) is still
consistent with its market value! Now that I have several hours
on the motor, I have to admit that I have come to really like
it. Possibly the lack of a reliable magneto was what previously jaded me to this era Scotts...... Thanks to AOMCI member Kevin S. who gave me 3 other '53
and '54 Scott/Firestone 5's to disassemble and photograph for
this article and to my editor R.C. who made some suggestions
to make things clearer and more readable.
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