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Engine: Lycoming O-340

The Lycoming O-340 is no different than either of its O-320 or O-360 brothers. The same goes for the care and maintenance. The difference is in some of the unique parts used. The 340 is a modified 320 with longer cylinder barrels and a crankshaft with a longer stroke to increase displacement and different piston connecting rods. This increases the compression to 8.5:1 and boosted power output to 170 hp (127 kW) over the O-320’s 150 hp. It is paired with a constant speed prop.

Important items of note: Do not keep prop at max rpm (2700) fore more than 2 minutes. Reduce manifold pressure to 25″ and lower prop to 2500RPM after initial climb-out to around 500-600 AGL.

Some of the parts/modifications unique to the O-340 are:

  • Larger center and rear crankshaft bearings
  • Larger bearing chambers in the crankcase, making it a -30 case.
  • A unique crankshaft
  • Shortened connecting rods
  • Shorter connecting rod bolts (can be cut down from longer bolts)
  • Unique air intake pipes, caused by the step down between cylinder and crankcase.
  • Longer push-rods and push-rod tubes
  • Carburetor limited to prevent full throttle.