Small generator sets first became popular in
the mid-1930s. These first generators were primarily used to
recharge 6-volt wet-cell batteries to operate lights and a radio
for evening entertainment on farms without electricity. Later, they
would be used for many different purposes including powering
independent lighting by direct connection. The gas engine washing
machine was very popular in rural America by this time.
Consequently, in 1937 the Briggs and Stratton Co. came up with the
idea to combine a washing machine engine with a generator to do
both jobs at once. At that time, their washing machine engine was
known as the Model WM, so this new unit became the Model WMG and
was called the “Start-Charger washer motor.” Not many of these
units still exist, possibly because of their location under a
washing machine, although records show that 9,242 were made.
Being an avid Briggs and Stratton collector, I had been looking
for generator units made by the company to add to my collection. By
February 2002, I had collected a PC 100 and a PC 304 generator set
when I came upon an ad on the Antique Small Engine Collectors Club
website (www.asecc.com). The ad was for a small WMG engine and
generator. The seller said the generator was probably not
restorable, but the engine was loose and the tag on the shroud
indicated Type 20651 and serial no. 1064. He said the generator was
very rusty but I made an offer for both.
I had previously found a rare copy of the operating instructions
for a Start-Charger washer motor at an engine show in New York.
Having studied this manual carefully, I was very excited when the
box finally arrived in the mail. Unfortunately, since the generator
and engine were shipped in the same box without packing, they
banged together, breaking the carburetor. The shroud was badly
dented, and the engine/generator base was so bent they would not
align when put together.
After this initial disappointment, I went to work stripping the
generator, as it seemed to be the biggest challenge. The generator
casing was missing and so was the top of the circuit breaker. As a
result of these missing covers, the generator’s insides were very
corroded, either from sitting under a washing machine for many
years or perhaps being out in the elements. I checked out the
armature and field coil, and as I expected both were shorted out
and would need rewinding.
The original casing would have had an inside diameter of 5-1/4
inches with a 1/8-inch wall thickness. I could only find 6-inch
tubing to fabricate the new casing, so I cut a section out of the
side; but when I welded it back together it formed a teardrop
shape. By squeezing the casing in a vice to an oval shape then
welding a bead up the inside, I was able to bring it back to a
proper circle that fit the field coil core perfectly. Next, I made
an endplate by turning down a 1/4-inch steel plate on the lathe,
then drilling cooling holes and a center hole for the bearing. An
automotive frost plug was pressed backwards into this hole, then
filled with two felt washers and pierced with an oil cap to make a
bearing cup.
New mounting studs were made from threaded rod, and a new
insulated brush mounting plate was made from a type of plastic
cardboard to replace the deformed original. The brushes were in
good enough shape to reuse with new springs attached. The generator
went back together after some persuasion.
The motor coupling was the next challenge. The coupling consists
of six studs attached to the outer facing of the engine pulley that
mated with a steel disc on the armature shaft of the generator. The
six holes in the disc were each lined with rubber that had badly
dried out and would need to be replaced. After much thought, I came
up with the idea of using rubber fuel line.
I trimmed the rubber hosing neatly to the correct length by
pushing a length of hose on a steel rod and turning it in a lathe
while using a sharp blade to do the cutting. The restored coupling
fit together very well, even though one of the pins had previously
been broken off.
Now it was time to work on the engine. It was missing the
muffler, gas tank and air shield. I bought a reproduction muffler
from Charles Camara of CPC Reproductions, Tiverton, R.I., and a gas
tank from eBay. A parts engine provided an air shield. I went to
work glass-beading all the parts of the stripped engine, lightly
honing the cylinder and lapping the valves smooth again.
Before the beading started on the shroud, I hammered it back
into shape. I re-aligned the engine base, which had to be straight
as it was also the mounting plate for the generator. A new ignition
wire, spark plug, set of piston rings and gasket set came from my
own stock of parts. After I cleaned up the flywheel, I gave the
magnets a zap on my magneto charger to give the engine a good hot
spark. Once all the parts had a smooth coat of black paint, the
engine went back together again with good compression, but it still
needed a carburetor. Once again, eBay provided the part, and after
a good cleaning it was mounted to the engine. The assembly was now
ready to mate with the generator. This marriage went smoothly and
my next step was to complete a mounting board.
My mounting boards are all made from laminated beech wood with
three or four coats of marine varnish to help protect against oil
and gas spills. I bored holes for mounting bolts and a large one
for draining the oil. This hole was lined with a piece of copper
drainpipe to prevent oil from contaminating the wood of the base. I
then mounted the engine and generator together on the board. All
that remained now was to complete the exterior wiring before
starting the unit up. This is where I ran into another snag.
Sitting on top of the generator is a circuit breaker, which is a
type of solenoid switch that prevents the battery being charged
from draining back into the generator should the engine run out of
gas. As with everything on this generator, it was also in sad
shape, and since the cover was missing the coil required rewinding.
I built a jig to rewind the coil and was all set to start when I
happened to mention what I was doing to a friend, Ross Walker, who
knows all about Model A Fords. He asked me why I was bothering to
rewind the coil. He told me they were notorious for not working
well and I should consider using a 6-volt diode instead, as they
worked well for the Fords he restored. This seemed like an easier
solution, so using his contact, I purchased some diodes and built
one into a heat sink that would fit on the original circuit breaker
base.
At this stage of the restoration in July 2005, I was attending
the Niagara Antique Power Assn. Show in Sherkston, Ontario. By now,
I had been working on this generator set since 2002, and I had been
promising to bring it to the next show and then the next, so I
finally decided to take it to this show. The problem was, I did not
have the time to start it in advance. As all restorers know this is
usually a bad idea, and for me this time was no exception.
Everything was wired properly and the only part missing was the
cover for the diode, but as you can guess, the engine would not
start. It seemed to be an ignition problem. I swallowed my pride,
and after the show was over I took the unit home and changed the
condenser. This seemed to help but the problem turned out to be a
weak coil.
So on July 16, 2005, with a new coil from the local B and S
dealer installed, the 6-volt battery hooked up and using the
generator as a starter motor, the engine started right up and ran
smoothly. The last hurdle was the cover for the circuit breaker. I
carved a wooden form and tried to create a cover with epoxy with no
success. Using fiberglass cloth was also not successful, so I
resorted to thin sheets of Plexiglas, which turned out very
well.
I took the completed generator to the Steam-Era at Milton,
Ontario, and to my surprise my “little gen set” won a prize as
“Best Restored Engine Under 3-1/2 HP.” The engine in this unit is
rated at 2/3 HP.
Contact engine enthusiast John Cox at:
2224 Wyandotte Drive,
Oakville,
ONT Canada L6L 2T5;
jcox109@cogeco.com
For more information on Briggs and Stratton engines, visit:
www.oldengine.org
