Fuel System; Repair Of Fuel Leaks; Carburetor Inlet Screen Assembly; Fuel Grades And Limitations - Lycoming O-290 Operator's Manual

SECTION 5
MAINTENANCE PROCEDURES
Some timing lights operate in the reverse manner as described above, the light comes on
when the breaker points open. Check your timing light instructions.
(4) After both magnetos have been timed, check, as described below, to ascertain that both magnetos
are set to fire simultaneously.
(5) Back off the crankshaft a few degrees, the timing lights should go out. Bring the crankshaft slowly
back in direction of normal rotation until the timing mark and the hole in the starter housing are in
alignment. At this point, both lights should go on simultaneously. Tighten nuts to specified torque
(150 in.-lbs.).
c. Generator or Alternator Output – The generator or alternator (whichever is applicable) should be
checked to determine that the specified voltage and current are being obtained.

2. FUEL SYSTEM.

a. Repair of Fuel Leaks – In the event a line or fitting in the fuel system is replaced; only a fuel soluble
lubricant, such as clean engine oil or Loctite Hydraulic Sealant, may be used on the threads. Any other
thread lubricant or compound must not be used.
b. Carburetor Inlet Screen Assembly – Remove and check the screen for distortion or openings in the
strainer. Replace for either of these conditions. Clean assembly in solvent and dry with compressed
air. To install the screen assembly, place the gasket on the assembly and install in the throttle body,
then tighten to 35 – 40 in.-lbs. torque.
c. Fuel Grades and Limitations – The recommended aviation grade for subject engines is listed in the
Engine Flight Chart on page 3-6 of this manual. In the event that the specified fuel is not available at
some locations, it is permissible to use higher octane fuel. Fuel of a lower octane than specified is not
to be used. Under no circumstances should automotive fuel be used (regardless of octane rating).
These engines are equipped with solid stem valves and should use higher octane fuel only for
limited operation. It is recommended that personnel be familiar with the latest revision of
Service Instruction No. 1070 regarding specified fuel for Lycoming engines.
d. Air Intake Ducts and Filter – Check all air intake ducts for dirt or restrictions. Inspect and service air
filters as instructed in the airframe manufacturer's handbook.
e. Idle Speed and Mixture Adjustment –
(1) Start the engine and warm up in the usual manner until oil and cylinder head temperatures are
normal.
(2) Check magnetos. If the "mag-drop" is normal, proceed with idle adjustment.
5-4
LYCOMING OPERATOR'S MANUAL
NOTE
NOTE
O-235 AND O-290 SERIES