Page 47 - Aeronca 11AC Interactive Service Manual

Aluminum alloy sheet is used in the fabrication of these parts. Air, upon entering the upper front of the
nose cowling, is forced around the cylinder fins of the engine assembly. Air from the upper cowling and
baffle chamber is passed through flexible aluminum tubing to muffs at the junction of the exhaust stack
“Y” on each side of the engine. The air is heated upon contact with the exhaust stacks, the left muff and
stack assembly providing heated air for cabin heater, the right muff and stack assembly providing heated
air for the carburetor heater assembly.

INTER-CYLINDER BAFFLES

Two baffles are incorporated below and between the cylinder heads and barrels on each side of the engine.
Supported with a spring and rod assembly these units complete the baffle system for the engine cylinders.
It is very important that these inter-cylinder baffles are in place at all times to prevent leakage of pressure
in the upper baffle system resulting in improper cooling.

CRANKCASE BAFFLES

These baffles are provided to force cool air around the crankcase of the engine. Outside air enters through
the lower front nose cowling building up pressure at the front of the crankcase.

HEAT CONTROL
Flow of the heated air to the carburetor heater and cabin heater is controlled from the engine control panel.

Caution: Leather binding around the upper cylinder baffles must always extend inward toward the engine
and forward. This insures a snug cowling and baffle fit when air pressure is exerted against the leather
binding in flight.

CARBURETOR HEATER
This assembly controls the flow of heated air from the baffle system to the carburetor venturi. A butterfly
valve connected to the carburetor heater control cable directs the airflow to the carburetor, when heat is
desired, or through the outlet at the bottom of the air scoop assembly when not in use.

Caution: Proper functioning of the heater butterfly valve may be determined as follows:

Set throttle at cruising RPM (2150 to 2200 RPM). Pull heater control on, RPMs should drop not less than
75 RPM, not more than 200 RPM.

If no change is noted check butterfly valve for proper seating.

Engine overhaul procedure, specifications and instructions are contained in the Continental Instruction
Manual.

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