The fuel system of the early gas engine is generally simple but
can cause its share of problems. The carburetor is likely to be one such problem area.
The engine piston on its intake stroke creates a vacuum in the
cylinder. Outside air, under atmospheric pressure, will try to push
into the cylinder. If we provide a small passageway through which
this air may enter and add a fuel jet, we have a simple carburetor
(I’ll abbreviate it to carb)–a device to vaporize liquid fuel
and mix it with air in correct ratio for combustion. Better
economy, variable speeds, acceleration, and power demands may
require added parts, but the basic carburetor remains essentially the
same. With that understanding, let’s do a little carburetor troubleshooting.
Edgar Johnson of Flemington, N.J. has a
1 1/2 HP Fairbanks-Morse Z engine with Bosch Hi-tension oscillator
ignition. The compressor is good and he has checked the spark plug,
timing, and carb. The engine runs OK under load but misses or stops
with no-load. His question: Could the mag be at fault? Or if not,
what is wrong?
I believe the trouble is in the fuel system, Ed. To check the
mag, remove the wire from the spark plug and place the end about
3/8 inch from the engine. Trip the mag lever. If the spark will
jump to the engine the mag should be OK. The fact that it fires the
engine under load when voltage demands are higher, indicates it is
OK.
To the above basic carb, FM has added the following: 1) A
restriction (venturi) in the carb throat for better mixing and fuel
suction; 2) A governer-operated throttle valve to control fuel-air
flow into the engine; 3) An automatic auxilliary air valve at the
air entrance to the carb, to improve fuel air ratio throughout the
load range of the engine; 4) A gasoline reservoir at the carb for
starting and 5) A fuel tank under the engine for running (with
kerosene if desired); 6) An extra jet for the tank fuel and a
hand-operated needle valve for each jet to adjust the fuel feed; 7)
A ball-check valve at the bottom of the fuel supply tube in the
fuel tank to hold the fuel level in the tube at or near the level
of the carb jet.
Since items 1, 2, 3, cause severe impedance to air flow, air
will try to enter the engine where it is not supposed to. Cheek for
leaking gaskets or loose connections between the carb, throttle
valve assembly, and engine. Check for a weak exhaust valve spring
or too strong a spring on the intake valve. Be sure the ball-check
valve (7) is there and that it is free. Clean and check the gauze
filter screen on the same valve. Be sure the pressed in jet and
needle valve assemblies (6) haven’t worked loose. (A good
present day fix for this is epoxy glue.)
A good idea whether the engine is running good or bad is to
check the speed occasionally. With our every-day association with
high speed many-cylinder engines that idle at speeds in excess of
the operating speeds of many of the old-timers, it’s easy to
over speed the old ones. A simple direct reading tachometer can be
purchased at most farm supply stores for a few bucks and can be a
good investment. Poor carburetion, excessive vibration, and
lubrication failures can often be traced to excessive speed. Most
engines have their operating speed stamped on them.
Albert Erbele of Lehr, N. Dak. has a
1 1/2 hp John Deere that will run only with
the choke half closed. He has checked most of things I have
mentioned. The carb on this engine is basic with only a slightly
more elaborate jet with hand-operated needle valve, a ball-check
valve in the fuel tank, and a hand choke. The fuel tank is partly
the engine base and partly a pan fastened to the base.
Remember
that the air is flowing into the carb because the pressure is less
inside the carb. The fuel flows for the same reason, being pushed
by outside air pressure. On the John Deere the fuel tank is
practically air tight. To allow the air to get in to “push”
the fuel a small hole is drilled in the engine base just below the
fuel filler plug and toward the cranking and ignition side. Be sure
rust, dirt, or paint hasn’t plugged this hole. If you can’t
find it drill an 1/8 inch hole in the filler plug.
If the exhaust is emitting black smoke, indicating an over-rich
fuel-air mix, and the engine will not run without this rich mix
check for weak ignition. This might be poor igniter ground, bad
wire or connection, weak mag, or mag out of time.
One of the venerable engine and equipment companies that has
passed from the scene is Emerson-Brantingham of Rockford, III. Spencer Lee of Proctor, Minn. would like
any information he can get on this company and its gas engines,
since he has a 1 1/2 hp model No. 11,670.
My notes indicate this company was founded in 1852, and the Gas
Review for Sept. 1912 mentioned E-B had increased their stock
issue to $50 million and purchased non-competetive lines including
LaCrosse Hay Tool Co., Chicago Heights, III.; Gas Traction Co.,
Minneapolis, Minn.; The Geiser Co., Waynesboro, Pa.; and Reeves
Co., Columbus, Ind.
I do not know which one of these companies brought stationary
and portable gas engines to E-B, but would guess it to be Geiser,
the only one of the companies mentioned that were listed as a gas
engine builder in 1906.
Emerson engines were probably built under the E-B name until E-B
was acquired by Case in 1928. Maybe someone can furnish us with
more information on this.