Teledyne Continental Motors, Inc.
TM
Engine
Description
IOF-550 Permold Series Engine Maintenance Manual
2-9
1 April 2007
2-2.3. Cylinders
The IOF-550 Permold Series engines have six, horizontally-opposed, air cooled
cylinders, three on the left side and three on the right side of the engine. The cylinders,
pistons and valve drive train provide the momentum to sustain crankshaft movement.
Aviation fuel and air are drawn into a cylinder during the intake stroke, compressed by
the piston during the compression stroke and then ignited by a high intensity spark from
each spark plug (two per cylinder). As the mixture is ignited, the expanding gases force
the piston to move inward toward the crankshaft during the power stroke.
The head and barrel assembly consists of externally finned aluminum alloy head casting
and a steel, nitrided cylinder barrel for wear resistance. Helical coil thread inserts are
installed in upper and lower spark plugs holes. A rotocoil assembly retains two concentric
springs surrounding the exhaust valve and is locked to the stem by tapered, semi-circular
keys which engage grooves around the valve stems. An outer retainer holds two
concentric springs which surround the intake valve which is locked to the stem by
tapered, semi-circular keys which engage grooves on the stem.
The IOF-550-B and C engine cylinder head design has intake and exhaust ports located
on the bottom of the cylinder as installed on the engine. This design is referred to as an
“updraft configuration.” (Figure 2-6) The valve rocker cover is one piece made of painted
die-cast aluminum.
The IOF-550-N, P, and R series engines use a cross flow (Figure 2-7) cylinder head
design. The intake ports are located on top of the cylinder head while the exhaust ports
are located below. There are separate intake and exhaust valve rocker covers made from
zinc-plated stamped sheet steel. This cylinder design is used in conjunction with a
Balanced Induction System mounted above the engine.
All of the IOF-550 Permold series engines employ an inclined valve design. The inclined
valve design permits the creation of a hemispherical dome in the top of the combustion
chamber which improves airflow efficiency through the cylinder head. The intake valve
seat is a Venturi style seat permitting improved airflow into the cylinder combustion
chamber. The exhaust valve is a solid design and transfers the heat generated during
combustion directly into the exhaust valve seat where it is radiated into the cylinder head.