O-320 Narrow Deck Only the Lycoming factory delivers Cool, Hard, Tough, Genuine Lycoming Cylinders. The BEST Cylinders you can fly. Lycoming’s advanced metallurgical department engineers our cylinder barrels. O-320-E2D, -E3D Series. Illustrated Parts Catalog. 652 Oliver Street© Williamsport, PA 17701.
Lycoming 0-320 series engines
The Lycoming 0-320 series engines of 150-hp to 160-hp look very much like the four-cylinder Lycomings of lesser power. The increased cubic-inch displacement is the result of increased bore. Stroke is the same as the O-235's and O-290's - 3.875 inches. All modern light plane engines of the opposed cylinder layout are over-square. That is, stroke is markedly less than bore. A short stroke holds down piston speeds and reduces wear.
In design and operation, the O-320's tappets are almost identical to the hydraulic tappets used on Continental engines. As the camshaft lobe actuates the cam follower and pushes the hydraulic lifter cylinder outward, the oil in the chamber acts as a cushion. While the engine valve is off its seat a bit of oil leaks between the plunger and cylinder bore to compensate for any contraction or expansion in the valve train. Then, as the cam lobe moves off the follower and the engine valve closes, the supply chamber immediately refills and prepares for another cycle.
The 0--320series engines have provision in the crankcase (ahead of number one cylinder) for a hydraulic propeller installation. Also, the chrome moly crankshaft on some models are fitted with a pair of small propeller flange bushings which allow this shaft, designed for constant-speed propellers, to accommodate a controllable-pitch prop. But crankshafts intended for constant speed props may not be substituted for shafts in fixed pitch installations unless the plug, in the rear of the hollow front section of the shaft, is installed. (Or removed, if switching from fixed-pitch to controllable pitch). The 0-320 in the used market may or may not have chromed cylinder barrels. Just make sure that you never put chromed piston rings into a chromed cylinder barrel, because something has to give, and chrome against chrome makes this impossible. As a general rule, Lycoming chromes the cylinder barrels of its higher horsepower engines in manufacture, while Continental prefers to use chrome rings.
Internal engine lubrication is conventional on the 0--320s. Mains, con rods, camshaft bearings, tappets, and pushrods are pressure lubricated. Oil collectors and spray lubricate the piston pins, cylinder walls, and gears. The oil pump, located in the accessory housing, sucks oil from the sump and sends it through a drilled passage in the accessory housing a threaded connection on the rear face of the housing, through a flex line and into the external cooler. Pressure oil from the oil cooler returns to another threaded connection on the accessory housing and goes through a drilled passage to the oil pressure screen, which is in a casting mounted on the accessory housing. If cold oil or an obstruction should restrict the oil flow to the cooler, a bypass valve allows the oil to flow directly from the oil pump to the oil pressure screen chamber.
From the pressure screen chamber, oil flows through a drilled passage to the pressure relief valve (located on the upper right side of the crankcase ahead of the accessory housing), and this relief valve maintains proper oil pressure in the engine by diverting excess oil back into the sump. The pressure oil is then fed to the main oil gallery in the right half of the crankcase.
Flowing through this main gallery, the oil is distributed to the drilled passages which take it to the main bearings of the crankshaft. Angular holes are drilled through the mains to the rod journals where sludge removal tubes are located. Thus the centrifugal force of the crankshaft in motion removes sludge and foreign matter that may be in the oil.
Drilled passages from the rear main send oil to the crankshaft idler gear shafts. And oil from the main oil gallery also flows to the cam and valve gear passages, and then through branch passages to the hydraulic tappets and cam bearings. Oil enters the tappet through indexing holes and goes out through the hollow pushrods to the valve mechanism, lubricating the rocker bearings and valve stems.
The 0-320 Lycomings have an ignition system similar to that of the 0-235 arid 0-290 engines, and also employ the Scintilla 84LN-20 and –21 magnetos, except as noted in the model list below. The induction system, too is practically the same, except that the 0-320 is fitted with a Marvel-Schebler MA-4SPA carbureytor.
The AN 20010 propeller governor drive furnished with the 0-320 allows installation of a constant speed governor and a single - acting controllable pitch prop. High pressure oil is carried from the governor, which is mounted on the accessory housing, to the front of the crankcase by way of an external oil line. The oil then flows into the hollow front section of the crankshaft through indexing holes in the crankcase, front main bearing, and crankshaft.
Specifications - 0-320-A
| Cylinder bore | 5.125 in. |
| Stroke | 3.875 in. |
| Displacement, cubic inches | 319.8 |
| Compression ratio | 7.00:1 |
| Rated rpm | 2,700 |
| Rated horsepower | 150 |
| Cruising rpm | 2,450 |
| Dry weight | 268 lbs. |
| Oil pressure, normal | 65 to 85 psi |
| Oil pressure, minimum at idle | 25 psi |
| Oil sump capacity | 8 qts |
| Fuel grade, octane | 80/87 |
| Spark advance, BTC | 25 degrees |
| Tappet setting, cold engine | .028 to .080 inches |
Lycoming 0-320 Series
Following is a complete list of the 0-320 series:
Model | Hp | rpm | Fuel | C.R. | Description |
0-320-AlA | 150 | 2700 | 80/87 | 7.00:1 | Controllable prop, 25-deg spark advance |
0-320-A2A | 150 | 2700 | 80/87 | 7.00:1 | Same as A1A but fixed pitch propeller |
0-320-A3A | 150 | 2700 | 80/87 | 7.00:1 | Same as A1A with 7/16' prop bolts |
0-320-A1B | 150 | 2700 | 80/87 | 7.00:1 | Same as A1A with straight riser in oil sump and -32 carburettor |
0-320-A2B | 150 | 2700 | 80/87 | 7.00:1 | Same as A2A with straight riser in oil sump and -32 carburettor |
0-320-A2C | 150 | 2700 | 80/87 | 7.00:1 | Same as A2B with retard breaker mags |
0-320-A2A | 150 | 2700 | 80/87 | 7.00:1 | Same as E3D with conical mounts |
0-320-A3B | 150 | 2700 | 80/87 | 7.00:1 | Same as A3A except for straight riser in oil sump and -32 carburettor |
0-320-A3C | 150 | 2700 | 80/87 | 7.00:1 | Same as A3B except for retard breaker mags |
0-320-B1A | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as A1A but high compression |
0-320-B2A | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as B1A but fixed pitch propeller |
0-320-B3A | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as B1A except 7/16 prop bolts |
0-320-B1B | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as B1A except straight riser in oil sump and -32 carburettor |
0-320-B2B | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as B2A except straight riser in oil sump and -32 carburettor |
0-320-B2C | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as B2B except retard breaker mags |
0-320-B3B | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as B1A except E 7/16 prop bolts, straight riser in oil sump, and -32 carburettor |
0-320-B3C | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as B3B except retard breaker mags |
0-320-C1A through | 150 | 2700 | 80/87 | 7.00:1 | Low compression field service conversions of B1A through B3C |
0-320-L1A | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as B3B but type one dynafocal mounts |
0-320-D2A | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as D1A but with fixed pitch prop and 3/8 attaching bolts |
0-320-D1B | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as D1A but retard breaker mags |
0-320-D2B | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as D2A but retard breaker mags |
0-320-D1C | 160 | 2700 2700 | 100/30 or91/96 | 8.50:1 | Same as D2C but provision for controllable prop |
0-320-D2C | 160 | 2700 | 100/130 or 91/96 | 8.50:1 | Same as D2A except-1200 series mags |
0-320-D1F | 160 | 2700 | 80/87 | 7.00:1 | Same as E1F except high compression pistons |
0-320-D2F | 160 | 2700 | 80/87 | 7.00:1 | Same as E2F except high compression pistons |
0-320-ElA | 150 | 2700 | 80/87 | 7.00:1 | Same as A3B but with type 1 dynafocal mounts |
0-320-E2A | 150/ 140 | 2700/ 2450 | 80/87 | 7.00:1 | Same as E1A but fixed pitch prop, 3/8 attaching bolts, and alternate rating of 140- hp |
0-320-E1B | 150 | 2700 | 80/87 | 7.00:1 | Same as E1A except retard breaker mags |
0-320-E2B | 150 | 2700 | 80/87 | 7.00:1 | Same as E2A except retard breaker mags |
0-320-E1C | 150 | 2700 | 80/87 | 7.00:1 | Same as E1B |
0-320-E2C | 150/ 140 | 2700/2450 | 80/87 | 7.00:1 | Same as E2A but -1200 series mags and alternate rating of 140-hp |
0-320-E2D | 150 |
| 80/87 | 7.00:1 | Similar to E2A but with Slick 'throw away' mags and 0-235 front |
0-320-E3D | 150 | 2700 2700 | 80/87 | 7.00:1 | Same as E2D but with3/8 prop flange bolts |
0-320-ElF | 150 | 2700 2700 | 80/87 | 7.00:1 | Same as E1C but with prop governor drive on left-front of crankcase |
0-320-E2F | 150 | 2700 | 80/87 | 7.00:1 | Same as E1F but with fixed pitch prop |
0-320-E2G | 150 | 2700 | 80/87 | 7.00:1 | Same as E2D but with0-320-A sump and take pipes |
0-320-E2H | 150 | 2700 | 80/87 | 7.00:1 | Same as E2D but with S4LN-20 and -21 mags |
0-320-E3H | 150 | 2700 | 80/87 | 7.00:1 | Same as E3D but with S4LN-20 and -21 mags |
The IO-320's are equipped with Bendix fuel injection systems and are designated 10-320-AlA through AI0-320-C1B. The I0-320-AlA, -A2A, -E1A, and -E2A are 150-hp and use 80/87 fuel. All others are rated at 160-hp @ 2700 rpm with 8.50:1 compression ratios. Significant models are:
| LIO-320-B1A | 160 | 2700 | 100/130 | 8.50:1 | Similar to 10-320-BlA but with left hand rotation |
| LIO-320- CIA | 160 | 2700 | 100/130 | 8.50:1 | Similar to 10-320-C1A but with left hand rotation |
| L10-320- C1A | 160 | 2700 | 100/130 | 8.50:1 | Same as B1B but converted for turbocharger; long reach spark plugs, piston cooling oil jets, -21 mags and AN fuel pump drive |
| AIO-320- A1A | 160 | 2700 | 100/ 130 or 91/96 | 8.50:1 | Aerobatic engine with Bendix RSA-5ADI fuel injection |
The aerobatic version is also available with fixed pitch prop (AIO-320-A2A), impulse coupling magneto (-A1B), and front mounted fuel injector (-B1B).
THE HEALTH OF YOUR ENGINE
The engine compression check or differential pressure test is integral to determining the health of an engine. Most people in the aviation community are familiar with the test but not many really know how or why it’s done. Here is a quick look at how a basic engine compression inspection is carried out and some follow up actions that maybe necessary as a result of the test.
The engine compression inspection checks the condition of the working parts in the combustion chamber of a cylinder. This is accomplished by measuring the static leak rate of the cylinder as compared to the leak rate through an orifice of specified size. This is done by attaching a differential compression measuring device, which incorporates the orifice, two pressure gauges, with a regulator to one spark plug hole of the cylinder under test while the piston is at top dead center of the compression stroke.
Lycoming O 320 H2ad Manual
Lycoming recommends a compression check of the cylinders any time you encounter loss of power, increasing oil consumption, hard-starting, or evidence of unexplained abnormal operation, and to check the health of the engine at 100 hour or annual inspection intervals.
Before the inspection, the engine must be run until the cylinder head and oil temperatures are in the normal range. The test should be completed as soon as practical after shut down. A differential compression measuring device is attached to the cylinder via the spark plug hole after the piston is positioned at top dead center of the compression stroke. Shop air is supplied to the tester and the regulator is adjusted to 80 PSI as air is sent is to the cylinder through the tester. To assure that the piston rings are seated, the propeller is moved slightly back and forth with a rocking motion. The cylinder compression reading is taken from the gauge on the downstream side of the orifice and recorded as “X” psi over 80. Pressure readings for all cylinders should be nearly equal. Each engine manufacturer sets the limits for differential pressure and the appropriate service information should be referenced for this criteria.
Lycoming offers the following guidance. A difference of 5 psi between cylinders is satisfactory; a difference of 10 to 15 psi indicates an investigation should be made. Unless the pressure difference exceeds 15 psi the investigation does not necessarily mean removal of the cylinder. A follow-on compression check should be made within the next 10 hours of operation to determine the wear rate. If the pressure reading is below 60 psi or if the wear rate increases rapidly, as indicated by an appreciable decrease in cylinder pressure, removal and overhaul or replacement of the cylinder(s) should be considered.
YOU CAN SAVE COSTS
Failing to warm up the engine or to do the 10-hour recheck can be expensive. The cold engine shortcut might save time before the test but it may fail to properly identify a poorly operating cylinder. Conversely, often during the 10-hour operating period, valves reseat themselves and compression improves to acceptable levels, thereby saving the cost of a cylinder.
Lycoming 0 320 Specs
Questions, please contact:
Cessna Customer Care
316-517-5800 or 1-800-423-7762
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