Tower Hobbies .40 ENGINE Instructions For

INSTRUCTIONS FOR
®
.40 ENGINE
Please read and follow this instruction manual before operating your engine.
Thank you for purchasing this high quality Tower .40 engine. Your engine was
produced to exacting tolerances with state-of-the-art computerized machine
equipment using the finest materials and should provide consistent, reliable
service for many years. The new safety needle valve design feature of this
engine is a step forward in engine technology, offering safer operation than
conventional needle valve locations. The ABC construction and schnuerle porting
will provide you with performance to meet your sport flying needs, along with
easy starting and reliability. Like all model airplane engines, care must be taken
in operation as severe injury can result from improper or careless use. Please
read and understand the safety precautions and warnings in this manual before
operating this engine.
Glow Plug
Pressure Fitting
Muffler

Parts of the Engine:

Crankshaft: The crankshaft transforms the reciprocating motion of the piston into
rotational motion. The propeller is mounted on the portion of the crankshaft protruding
from the crankcase.
Propeller Nut: The propeller nut secures the propeller to the crankshaft.
Propeller Washer: The propeller washer provides a larger, stronger surface area to
apply pressure to the propeller.
Drive Washer: The drive washer is keyed to the crankshaft and is knurled on one face
to provide a good contact surface for the propeller.
Carburetor: The carburetor meters the amount of fuel and air that enters the engine.
Crankcase: The crankcase houses the internal parts.
Cylinder Head: The cylinder head is mounted on top of the crankcase. It provides a
seal at the top of the cylinder. The fins on the cylinder head provide a cooling surface.
The cylinder head also holds the glow plug.
Glow Plug: The glow plug provides the heat needed to ignite the fuel in the cylinder.
Muffler: The muffler quiets the exhaust exiting the cylinder.
Pressure Fitting: A tube is connected from the pressure fitting to the fuel tank. When
the engine is running, pressure from the muffler is used to pressurize the fuel tank.
Important:
© Copyright, 1998
Cylinder Head
Crankcase
Carburetor
Drive Washer
Propeller
Washer
Propeller Nut Crankshaft
Needle Valve: The needle valve controls the
fuel/air mixture entering the carburetor.
Air Bleed Screw: The air bleed screw controls
the amount of fuel/air mixture entering the
®
carburetor while the engine is idling.
Idle Stop Screw: The idle stop screw controls
how far the throttle closes. We suggest that it
be set to allow the throttle to close completely
to stop the engine using the throttle trim on the transmitter.
Throttle Arm: The throttle arm is connected to the carburetor barrel and is operated by
the throttle servo. By moving the throttle arm,
the barrel can be opened and closed. This
adjusts the speed of the engine.
By loosening the nut next to the carburetor
body, the safety needle valve can be rotated.
By loosening the nut below the fuel inlet, the
inlet can be rotated. An optional straight
needle valve adapter (TOWG5260) is available
if the engine will be enclosed in a cowl.
The aluminum piston and chrome-plated brass cylinder are designed to have the proper
fit at normal operating temperature. As the engine warms up, each part expands,
producing the proper fit. If the fuel mixture entering the engine is wrong, the parts do not
expand properly. The engine will not run correctly and in some cases can be damaged.
The reason the fuel mixture is so important is that the fuel is a blend of oil (synthetic oil
and/or castor oil), nitromethane and alcohol; plus anti-wear and anti-foaming agents and
corrosion inhibitors. The Tower .40 engine will run best on fuel with a 5% to 15%
nitromethane content and a mixture containing castor oil or a castor-synthetic blend. The
nitromethane helps the alcohol burn better. The oil lubricates and cools the engine. So, if
the fuel mixture is not correct, the engine can overheat or will not get hot enough for the
cylinder to expand properly and provide maximum power.
The beams the engine is to be mounted on must be rigid, parallel with each other and
the top surfaces in the same plane.
Beams are parallel
Beams are not parallel

Parts of the Carburetor:

Loosen this
nut to rotate
the needle
valve.

How the Tower .40 Engine Operates:

Installation:

CORRECT
INCORRECT
Top surfaces are not in
the same plane
Idle Stop
Screw
Needle
Valve
Air Bleed
Screw
Throttle Arm
Loosen
this nut to
rotate the
fuel inlet.
Top surfaces
of beams are
in the same
plane
Top surfaces
of beams are
not parallel