Textron LYCOMING O-320 Series User manual

Operator’s Manual
Lycoming
O-320 Series
Approved by FAA
3rd Edition Part No. 60297-30
652 Oliver Street
Williamsport, PA. 17701 U.S.A.
570/323-6181
October 2006

O-320 Series Operator’s Manual
Lycoming Part Number: 60297-30
©2006 by Lycoming. All rights reserved.
Lycoming and “Powered by Lycoming” are trademarks or registered trademarks of
Lycoming.
All brand and product names referenced in this publication are trademarks or registered
trademarks of their respective companies.
For additional information:
Mailing address:
Lycoming Engines
652 Oliver Street
Williamsport, PA 17701 U.S.A.
Phone:
Factory: 570-323-6181
Sales Department: 570-327-7268
Fax: [phone]
Lycoming’s regular business hours are Monday through Friday from 8:00 AM
through 5:00 PM Eastern Time (-5 GMT)
Visit us on the World Wide Web at:
http://www.lycoming.textron.com

LYCOMING OPERATOR’S MANUAL
ATTENTION
OWNERS, OPERATORS, AND MAINTENANCE PERSONNEL
This operator’s manual contains a description of the engine, its specifications, and detailed information on
how to operate and maintain it. Such maintenance procedures that may be required in conjunction with
periodic inspections are also included. This manual is intended for use by owners, pilots and maintenance
personnel responsible for care of Lycoming powered aircraft. Modifications and repair procedures are
contained in Lycoming overhaul manuals; maintenance personnel should refer to these for such procedures.
SAFETY WARNING
Neglecting to follow the operating instructions and to carry out periodic maintenance procedures can result
in poor engine performance and power loss. Also, if power and speed limitations specified in this manual
are exceeded, for any reason, damage to the engine and personal injury can happen. Consult your local
FAA approved maintenance facility.
SERVICE BULLETINS, INSTRUCTIONS, AND LETTERS
Although the information contained in this manual is up-to-date at time of publication, users are urged to
keep abreast of later information through Lycoming Service Bulletins, Instructions and Service Letters
which are available from all Lycoming distributors or from the factory by subscription. Consult the latest
revision of Service Letter No. L114 for subscription information.
NOTE
The illustrations, pictures and drawings shown in this publication are typical of the subject matter they
portray; in no instance are they to be interpreted as examples of any specific engine, equipment or part
thereof.
iii

LYCOMING OPERATOR’S MANUAL
IMPORTANT SAFETY NOTICE
Proper service and repair is essential to increase the safe, reliable operation of all aircraft engines. The
service procedures recommended by Lycoming are effective methods for performing service operations.
Some of these operations require the use of tools specially designed for the task. These special tools must be
used when and as recommended.
It is important to note that most Lycoming publications contain various Warnings and Cautions which
must be carefully read in order to minimize the risk of personal injury or the use of improper service
methods that may damage the engine or render it unsafe.
It is also important to understand that these Warnings and Cautions are not all inclusive. Lycoming could
not possibly know, evaluate or advise the service trade of all conceivable ways in which service might be
done or of the possible hazardous consequences that may be involved. Accordingly, anyone who uses a
service procedure must first satisfy themselves thoroughly that neither their safety nor aircraft safety will be
jeopardized by the service procedure they select.
iv

WARRANTY
NEW AND REBUILT ENGINES
(1) WARRANTY AND REMEDY: Lycoming Engines, a division of Avco Corporation (hereinafter “Lycoming”)
warrants each new Lycoming reciprocating engine to be free from defect in material or workmanship under normal
use and service. Lycoming’s sole obligation under this warranty is limited to replacement or repair of parts which
are determined by Lycoming to have been defective within a period of twenty-four (24) months after new aircraft
delivery to the original retail purchaser or first user, or twenty-four (24) months from the date of first operation. The
warranty period of twenty-four (24) months commences on the earlier of the date of first operation after new aircraft
delivery to the original retail purchaser or first user, or twenty-four (24) months from the date of shipment from
Lycoming. Lycoming will, in connection with the foregoing warranty, cover reimbursement of reasonable freight
charges with respect to any such warranty replacement or repair.
(2) Within the warranty period, Lycoming will reimburse the Purchaser for labor charges associated with warranty
related issues. Lycoming will only reimburse the cost of such labor charges in connection with repair or
replacement of parts as provided in Lycoming’s then current Removal and Installation Labor and Allowance
Guidebook. Spare parts installed as warranty replacement on engines which are covered by this New Engine
Warranty will be warranted for the balance of the original warranty period or for the spare part warranty, whichever
is the greater. Replacement of parts may be with either new or reconditioned parts, at Lycoming’s election. A claim
for warranty on any part claimed to be defective must be reported in writing to Lycoming’s Warranty
Administration within 60 days of being found to require repair or replacement by the purchaser or service facility.
Warranty adjustment is contingent upon the Purchaser complying with the Lycoming’s Warranty Administration
disposition instructions for defective parts. Failure to comply with all of the terms of this paragraph may, at
Lycoming’s sole option, void this warranty.
(3) THIS WARRANTY IS GIVEN AND ACCEPTED IN PLACE OF (i) ALL OTHER WARRANTIES OR
CONDITIONS, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES
OR CONDITION OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AND (ii) ANY
OBLIGATION, LIABILITY, RIGHT, CLAIM OR REMEDY IN CONTRACT OR IN TORT (DELICT),
INCLUDING PRODUCT LIABILITIES BASED UPON STRICT LIABILITY, NEGLIGENCE, OR IMPLIED
WARRANTY IN LAW AND PURCHASER HEREBY WAIVES SUCH RIGHTS AND CLAIMS.
(4) THIS WARRANTY IS THE ONLY WARRANTY MADE BY LYCOMING. THE PURCHASER’S SOLE
REMEDY FOR A BREACH OF THIS WARRANTY OR ANY DEFECT IN A PART IS THE REPAIR OR
REPLACEMENT OF ENGINE PARTS AND REIMBURSEMENT OF REASONABLE FREIGHT CHARGES AS
PROVIDED HEREIN. LYCOMING EXCLUDES LIABILITY, WHETHER AS A RESULT OF A BREACH OF
CONSEQUENTIAL DAMAGES, INCLUDING, BUT NOT LIMITED TO, DAMAGE TO THE ENGINE OR
OTHER PROPERTY (INCLUDING THE AIRCRAFT IN WHICH THE ENGINE IS INSTALLED), COSTS AND
EXPENSES RESULTING FROM REQUIRED CHANGES OR MODIFICATIONS TO ENGINE COMPONENTS
AND ASSEMBLIES, CHANGES IN RETIREMENT LIVES AND OVERHAUL PERIODS, LOCAL CUSTOMS
FEES AND TAXES, AND COSTS OR EXPENSES FOR COMMERCIAL LOSSES OR LOST PROFITS DUE TO
LOSS OF USE OR GROUNDING OF THE AIRCRAFT IN WHICH THE ENGINE IS INSTALLED OR
OTHERWISE. LYCOMING’S TOTAL LIABILITY FOR ANY AND ALL CLAIMS RELATED TO ANY
ENGINE SHALL IN NO CASE EXCEED THE ORIGINAL SALES PRICE OF THE ENGINE. SELLER MAKES
NO WARRANTY AND DISCLAIMS ALL LIABILITY WITH RESPECT TO COMPONENTS OR PARTS
DAMAGED BY, OR WORN DUE TO, CORROSION.

(5) This warranty shall not apply to any engine or part thereof which has been repaired or altered outside
Lycoming’s factory in any way so as, in Lycoming’s sole judgment, to affect its durability, safety or reliability, or
which has been subject to misuse, negligence or accident. Repairs and alterations which use or incorporate parts and
components other than genuine Lycoming parts or parts approved by Lycoming for direct acquisition from sources
other than Lycoming itself are not warranted by Lycoming, and this warranty shall be void to the extent that such
repairs and alterations, in Lycoming’s sole judgment, affect the durability, safety or reliability of the engine or any
part thereof, or damage genuine Lycoming or Lycoming-approved parts. No person, corporation or organization,
including Distributors of Lycoming engines, is authorized by Lycoming to assume for it any other liability in
connection with the sale of its engines or parts, nor to make any warranties beyond the foregoing warranty nor to
change any of the terms hereof. NO STATEMENT, WHETHER WRITTEN OR ORAL, MADE BY ANY
PERSON, CORPORATION OR ORGANIZATION, INCLUDING DISTRIBUTORS OF LYCOMING ENGINES
MAY BE TAKEN AS A WARRANTY NOR WILL IT BIND LYCOMING. NO AGREEMENT VARYING THE
TERMS OF THIS WARRANTY OR LYCOMING’S OBLIGATIONS UNDER IT IS BINDING UPON
LYCOMING UNLESS IN WRITING AND SIGNED BY A DULY AUTHORIZED REPRESENTATIVE OF
LYCOMING.
(6) All legal actions based upon claims or disputes pertaining to or involving this warranty including, but not limited
to, Lycoming’s denial of any claim or portion thereof under this warranty, must be filed in the courts of general
jurisdiction of Lycoming County, Commonwealth of Pennsylvania or in the United States District Court for the
Middle District of Pennsylvania located in Williamsport, Pennsylvania. In the event that Purchaser files such an
action in either of the court systems identified above, and a final judgment in Lycoming’s favor is rendered by such
court, then Purchaser shall indemnify Lycoming for all costs, expenses and attorneys’ fee incurred by Lycoming in
defense of such claims. In the event Purchaser files such a legal action in a court other than those specified, and
Lycoming successfully obtains dismissal of that action or transfer thereof to the above described court systems, then
Purchaser shall indemnify Lycoming for all costs, expenses and attorneys’ fees incurred by Lycoming in obtaining
such dismissal or transfer.
(7) Any invalidity of a provision of this Warranty shall not affect any other provision, and in the event of a judicial
finding of such invalidity, this Agreement shall remain in force in all other respects.
Effective September 2006 Revision “M”
Lycoming Engines
652 Oliver Street
Williamsport, Pennsylvania
17701
[phone]
www.lycoming.textron.com

LYCOMING OPERATOR’S MANUAL
TABLE OF CONTENTS
Page
SECTION1 DESCRIPTION 1-1
SECTION2 SPECIFICATIONS 2-1
SECTION 3 OPERATING INSTRUCTIONS 3-1
SECTION 4 PERIODIC INSPECTIONS 4-1
SECTION 5 MAINTENANCE PROCEDURES 5-1
SECTION6 TROUBLE-SHOOTING 6-1
SECTION 7 INSTALLATION AND STORAGE 7-1
SECTION8 TABLES 8-1
v

LYCOMING OPERATOR’S MANUAL
¾ Right Front View – Typical O-320 Series
¾ Left Rear View – Typical O-320 Series
vi

LYCOMING OPERATOR’S MANUAL
SECTION 1
DESCRIPTION
Page
General..........................................................................................................................................................1-1
Cylinders.......................................................................................................................................................1-1
Valve Operating Mechanism ......................................................................................................................1-1
Crankcase.....................................................................................................................................................1-1
Crankshaft....................................................................................................................................................1-1
Connecting Rods ..........................................................................................................................................1-1
Pistons...........................................................................................................................................................1-1
Accessory Housing.......................................................................................................................................1-1
Oil Sump.......................................................................................................................................................1-1
Cooling System.............................................................................................................................................1-2
Induction System..........................................................................................................................................1-2
Lubrication System......................................................................................................................................1-2
Priming System ............................................................................................................................................1-2
Ignition System.............................................................................................................................................1-2
Model Application Table.............................................................................................................................1-3

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LYCOMING OPERATOR’S MANUAL SECTION 1
O-320 SERIES DESCRIPTION
SECTION 1
DESCRIPTION
The O-320 series are four cylinder, direct drive and, horizontally opposed, air cooled engines.
In referring to the location of the various engine components, the parts are described in their relationship
to the engine as installed in the airframe. Thus, the power take-off end is considered the front and the
accessory drive end the rear. The sump section is considered the bottom and the opposite side of the engine
where the shroud tubes are located the top. Reference to the left and right side is made with the observer
facing the rear of the engine. The cylinders are numbered from front to rear, odd numbers on the right, even
numbers on the left. The direction of rotation for accessory drives is determined with the observer facing the
drive pad. The direction of rotation of the crankshaft, viewed from the rear, is clockwise.
Cylinders – The cylinders are of conventional air cooled construction with the two major parts, head and
barrel, screwed and shrunk together. The heads are made from an aluminum alloy casting with a fully
machined combustion chamber. Rocker shaft bearing supports are cast integral with the head along with
housings to form the rocker boxes for both valve rockers. The cylinder barrels, which are machined from
chrome nickel molybdenum steel forgings, have deep integral cooling fins and the inside of the barrels are
ground and honed to a specified finish.
Valve Operating Mechanism – A conventional type camshaft is located above and parallel to the crankshaft.
The camshaft actuates hydraulic tappets which operate the valves through push rods and valve rockers. The
valve rockers are supported on full floating steel shafts. The valve springs bear against hardened steel seats
and are retained on the valve stems by means of split keys.
Crankcase – The crankcase assembly consists of two reinforced aluminum alloy castings, fastened together
by means of studs, bolts and nuts. The mating surfaces of the two castings are joined without the use of a
gasket, and the main bearing bores are machined for use of precision type main bearing inserts.
Crankshaft – The crankshaft is made from a chrome nickel molybdenum steel forging. All bearing journal
surfaces are nitrided.
Connecting Rods – The connecting rods are made in the form of “H” sections from alloy steel forgings.
They have replaceable bearing inserts in the crankshaft ends and bronze bushings in the piston ends. The
bearing caps on the crankshaft ends are retained by two bolts and nuts through each cap.
Pistons – The pistons are machined from an aluminum alloy. The piston pin is of a full floating type with a
plug located in each end of the pin. Depending on the cylinder assembly, pistons may employ either half
wedge or full wedge rings. Consult the latest revision of Service Instruction No. 1037 for proper piston and
ring combinations.
Accessory Housing – The accessory housing is made from an aluminum casting and is fastened to the rear of
the crankcase and the top rear of the sump. It forms a housing for the oil pump and the various accessory
drives.
Oil Sump – The sump incorporates an oil drain plug, oil suction screen, mounting pad for carburetor, the
intake riser and intake pipe connections.
1-1

SECTION 1 LYCOMING OPERATOR’S MANUAL
DESCRIPTION O-320 SERIES
Cooling System – These engines are designed to be cooled by air pressure. Baffles are provided to build up
a pressure and force the air through the cylinder fins. The air is then exhausted to the atmosphere through
gills or augmentor tubes usually located at the rear of the cowling.
Induction System - Lycoming O-320 series engines are equipped with a float type carburetor. Particularly
good distribution of the fuel-air mixture to each cylinder is obtained through the center zone induction
system, which is integral with the oil sump and is submerged in oil, insuring a more uniform vaporization of
fuel and aiding in cooling the oil in the sump. From the riser the fuel-air mixture is distributed to each
cylinder by individual intake pipes.
A brief description of the carburetors follows:
The Precision Airmotive MA-4SPA and HA-6 carburetors are of the single barrel float type equipped with
a manual mixture control and an idle-cut-off.
Lubrication System – The lubrication system is of the pressure wet sump type. The main bearings,
connecting rod bearings, camshaft bearings, valve tappets, push rods and crankshaft idler gears are
lubricated by means of oil collectors and spray. The oil pump, which is located in the accessory housing,
draws oil through a drilled passage leading from the oil suction screen located in the sump. The oil from the
pump then enters a drilled passage in the accessory housing, where a flexible line leads the oil to the
external oil cooler. In the event that cold oil or an obstruction should restrict the flow of oil to the cooler, an
oil cooler bypass valve is provided. Pressure oil from the cooler returns to a second threaded connection on
the accessory housing from which point a drilled passage conducts the oil to the oil pressure screen, which
is contained in a cast chamber located on the accessory housing below the tachometer drive.
The oil pressure screen is provided to filter from the oil any solid particles that may have passed through
the suction screen in the sump. After being filtered in the pressure screen chamber, the oil is fed through a
drilled passage to the oil relief valve, located in the upper right side of the crankcase in front of the
accessory housing.
This relief valve regulates the engine oil pressure by allowing excessive oil to return to the sump, while
the balance of the pressure oil is fed to the main oil gallery in the right half of the crankcase. During its
travel through this main gallery, the oil is distributed by means of separate drilled passages to the main
bearings of the crankshaft. Separate passages from the rear main bearing supply pressure oil to both
crankshaft idler gears. Angular holes are drilled through the main bearings to the rod journals. Oil from the
main oil gallery also flows to the cam and valve gear passages, and is then conducted through branch
passages to the hydraulic tappets and camshaft bearings. Oil enters the tappets through indexing holes and
travels out through the hollow push rods to the valve mechanism, lubricating the valve rocker bearings and
valve stems. Residual oil from the bearings, accessory drives and the rocker boxes is returned by gravity to
the sump, where after passing through a screen it is again circulated through the engine. Pressure build-up
within the crankcase is held to a minimum by means of a breather located on the accessory housing.
Priming System – Provision for a primer system is provided on all engines.
Ignition System – Dual ignition is furnished by two magnetos. Consult Table 1 for model application.
Bendix magnetos are designed to permit periodic internal maintenance; Slick Electro magnetos are designed
to operate for approximately 900 hours without internal maintenance.
1-2

LYCOMING OPERATOR’S MANUAL SECTION 1
O-320 SERIES DESCRIPTION
TABLE 1
MODEL APPLICATION
Model Left Right Height Width Length
O-320
-A1A, -A1B S4LN-21 S4LN-20 22.99 32.24 29.56
-A2A*, -A2B* S4LN-21 S4LN-20 22.99 32.24 29.56
-A3A, -A3B S4LN-21 S4LN-20 22.99 32.24 29.56
-A2C*, -A3C S4LN-200 S4LN-204 22.99 32.24 29.81
-B1A, -B1B S4LN-21 S4LN-20 22.99 32.24 29.56
-B2A*, -B2B* S4LN-21 S4LN-20 22.99 32.24 29.56
-B3A, -B3B S4LN-21 S4LN-20 22.99 32.24 29.56
-B2C*, -B3C S4LN-200 S4LN-204 22.99 32.24 29.81
-B2D 4373 4370 19.22 32.24 31.28
-B2E 4373 4370 23.92 32.24 31.28
-D1A, -D2A* S4LN-21 S4LN-20 22.99 32.24 29.56
-D1B, -D2B* S4LN-200 S4LN-204 22.99 32.24 29.56
-D1C, -D2C* S4LN-1227 S4LN-1209 22.99 32.24 30.70
-D1F, -D2F* S4LN-1227 S4LN-1209 22.99 32.24 30.70
-E1A, -E2A* S4LN-21 S4LN-20 22.99 32.24 29.56
-E1B, -E2B* S4LN-200 S4LN-204 22.99 32.24 29.81
-E1C, -E2C* S4LN-1227 S4LN-1209 22.99 32.24 30.70
-E1F, -E2F* S4LN-1227 S4LN-1209 22.99 32.24 30.70
-E1J, -E2D*, -E3D* 4051 4050 22.99 32.24 29.05
-A2D*, -E2G* 4051 4050 22.99 32.24 29.05
-D2G, -D2H, -D3G 4051 4050 22.99 32.24 29.05
-E2H*, -E3H* S4LN-21 S4LN-20 22.99 32.24 29.56
-D1D 4051 4050 19.22 32.24 31.82
-D2J* 4251 4251 23.00 32.24 29.05
* - Fixed Pitch Propeller.
1-3

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LYCOMING OPERATOR’S MANUAL
SECTION 2
SPECIFICATIONS
Page
Explanatory Note.........................................................................................................................................2-1
Specifications – O-320-A, -B, -D, -E Series................................................................................................2-2
Accessory Drive Ratio..................................................................................................................................2-3
Detail Weights ..............................................................................................................................................2-3

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LYCOMING OPERATOR’S MANUAL SECTION 2
O-320 SERIES SPECIFICATIONS
SECTION 2
SPECIFICATIONS
The model specifications shown on the following pages of this section are divided according to model
designation. When differences among models can be clearly stated, the specifications of more than one
model are combined in a single group; otherwise, each model has its specifications listed separately. Also,
as additional models are added to this series, new specification pages containing data pertinent to the new
models will be added.
2-1

SECTION 2 LYCOMING OPERATOR’S MANUAL
SPECIFICATIONS O-320 SERIES
SPECIFICATIONS
O-320-A, -E* SERIES
FAA Type Certificate ....................................................................................................................................274
Rated horsepower...........................................................................................................................................150
Rated speed, RPM........................................................................................................................................2700
Bore, inches.................................................................................................................................................5.125
Stroke, inches..............................................................................................................................................3.875
Displacement, cubic inches.........................................................................................................................319.8
Compression ratio ....................................................................................................................................... 7.0:1
Firing order ............................................................................................................................................. 1-3-2-4
Spark occurs, degrees BTC..............................................................................................................................25
Valve rocker clearance (hydraulic tappets collapsed) ......................................................................... .028-.080
Propeller drive ratio ....................................................................................................................................... 1:1
Propeller drive rotation (viewed from rear) ........................................................................................Clockwise
* - O-320-E2A, -E2C, and –E2F have alternate rating of 140 HP at 2450 RPM.
O-320-B, -D** SERIES
FAA Type Certificate ....................................................................................................................................274
Rated horsepower...........................................................................................................................................160
Rated speed, RPM........................................................................................................................................2700
Bore, inches.................................................................................................................................................5.125
Stroke, inches..............................................................................................................................................3.875
Displacement, cubic inches.........................................................................................................................319.8
Compression ratio ....................................................................................................................................... 8.5:1
Firing order ............................................................................................................................................. 1-3-2-4
Spark occurs, degrees BTC..............................................................................................................................25
Valve rocker clearance (hydraulic tappets collapsed) ......................................................................... .028-.080
Propeller drive ratio ....................................................................................................................................... 1:1
Propeller drive rotation (viewed from rear) ........................................................................................Clockwise
** - O-320-D2H has alternate rating of 150 HP at 2500 RPM. O-320-D2J has alternate rating of 150 HP at
2500 RPM and 155 HP at 2600 RPM.
2-2

LYCOMING OPERATOR’S MANUAL SECTION 2
O-320 SERIES SPECIFICATIONS
*Accessory Drive Drive Ratio **Direction of Rotation
Starter 13.556:1 Counterclockwise
Starter 16.556:1 Counterclockwise
Generator 1.910:1 Clockwise
Generator 2.500:1 Clockwise
Alternator 3.250:1 Clockwise
Tachometer 0.500:1 Clockwise
Magneto 1.000:1 Clockwise
Vacuum Pump 1.300:1 Counterclockwise
Propeller Governor AN20010
Mounted on Accessory Housing 0.866:1 Clockwise
Mounted on Crankcase 0.895:1 Clockwise
Fuel Pump AN20003 1.000:1 Counterclockwise
Fuel Pump – Plunger Operated 0.500:1
Dual Drives
Vacuum – Hydraulic Pump 1.300:1 Counterclockwise
Vacuum Pump – Propeller Governor 1.300:1 Counterclockwise
* - When applicable.
** - Viewed facing drive pad.
DETAIL WEIGHTS
1. Engine, Standard, Dry Weight.
Includes carburetor, magnetos, spark plugs, ignition harness, intercylinder baffles, tachometer drive,
starter and generator (alternator) drive, starter and generator (alternator) with mounting bracket.
O-320 SERIES
LBS.
-E2D, -E3D, -E2G..........................................................................................................................................268
-A1A, -A1B, -A2A, -A2B, -A3A, -A3B, -A2C.............................................................................................272
-A3C, -E1A, -E2A, -E1B, -E2B, -E1C, -E2C................................................................................................272
-D2J, -E1J ......................................................................................................................................................275
-B2C, -B3C, -D1B, -D2B ..............................................................................................................................277
-B1A, -B1B, -B2A, -B2B, -B3A, -B3B.........................................................................................................278
-A2D, -D1A, -D1C, -D2A, -D2C, -E1F, -E2F ..............................................................................................278
-D2G, -D3G, -D2H ........................................................................................................................................281
-B2D, -B2E, -D1D .........................................................................................................................................283
-D1F, -D2F.....................................................................................................................................................285
2-3

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