Engine Specifications
Continental O-200-A limits, dimensions, and service data — Cessna 150 installation
Primary D971-13 — Cessna Aircraft Company. (1977). Cessna 150 series (1969–1976) service manual (D971-13, Change 3; Temporary Change 1, October 18, 1977). Section 1 (torque values), Section 2 (servicing, lubrication and inspection), Section 11 (engine). Aircraft-specific authoritative source; supersedes general engine references wherever values overlap.
X30010 — Continental Aircraft Engine Overhaul Manual, Form X30010 (FAA Approved, February 1980 ed.), FAA TC E-252 family. NTSB public docket, data.ntsb.gov.
M-0 / IO-550 App. B — Continental general fastener torque tables. NTSB public docket, data.ntsb.gov.
Every value on this page is taken directly from a source document. Verify all values against the current approved revision of D971-13 and applicable Continental publications before maintenance use. Values not listed here — including internal engine overhaul torques, compression limits, and spark plug gap — are published by the engine manufacturer; refer to the current Continental documentation for those.
General Engine Data
Source: D971-13, Section 11.
| Parameter | Value |
|---|---|
| Aircraft Model | Cessna 150J, K, L & M |
| Engine Model | Continental O-200-A |
| Rated Horsepower | 100 hp at 2,750 RPM |
| Number of Cylinders | 4, horizontally opposed |
| Displacement | 200.91 cubic inches |
| Bore | 4.0625 in |
| Stroke | 3.875 in |
| Compression Ratio | 7.00 : 1 |
| Firing Order | 1 – 3 – 2 – 4 |
| Crankshaft Rotation (viewed from rear) | Clockwise |
| Dry Weight (with accessories) | ~200 lb (varies with optional accessories) |
| Carburetor | Marvel-Schebler MA-3-SPA |
| Alternator | 14-Volt, 60-Ampere |
| Starter | 12-Volt, automatic engagement |
| Tachometer Drive | Mechanical |
| Cooling | Air-cooled; low-compression, direct-drive, driving a fixed-pitch propeller |
| Cylinder Numbering | Numbered rear to front. Right rear is No. 1; right side odd (1, 3). Left rear is No. 2; left side (2, 4) |
| Cylinder Head Temperature | Normal within green arc; maximum at red line |
Ignition System
Source: D971-13, Section 11 (magneto model, timing, drop limits, plug torque); X30010 (plug count, firing order cross-reference).
| Parameter | Value |
|---|---|
| Number of Magnetos | 2 |
| Magneto Model | Slick No. 4001 |
| Total Spark Plugs | 8 (2 per cylinder) |
| Right Magneto — Fires | Upper plugs, cylinders 1-3-2-4, at 24° (+1° / -0°) B.T.C. |
| Left Magneto — Fires | Lower plugs, cylinders 1-3-2-4, at 24° (+1° / -0°) B.T.C. |
| Timing Maintenance Schedule | Check at first 50 hr, first 100 hr, then every 200 hr. Timing tolerance: +0° / -2°. |
| Mag Drop Check — Test RPM | 1,700 RPM |
| Max Allowable Mag Drop (each) | 150 RPM |
| Max Mag Drop Differential (L vs. R) | 75 RPM |
| Internal (E-Gap) Timing | None in the field — set during manufacture; magnetos are not to be disassembled |
| Magneto Replacement Interval | Remove at 900 hours of magneto time; install new exchange magnetos |
| Magneto Timing Pin | 0.093 in (or a 6-penny nail) |
| Magneto Outlet Firing Sequence | Counterclockwise from No. 1 outlet, viewed at the outlets |
| Spark Plug Thread Size | 18 mm, into heli-coil type thread inserts |
| Spark Plug Construction | Shielded, with internal resistor |
| Spark Plug Type | Refer to current Continental active factory approved spark plug chart (manufacturer's official deferral — chart maintained separately by Continental) |
| Spark Plug Torque | 330 ± 30 lb-in (300 – 360 lb-in) — confirmed by D971-13, X30010, and Cessna Flyer Assoc. |
| Spark Plug Service | At each 100-hr inspection: remove, clean, inspect and regap all plugs; swap upper and lower plugs (lower plugs deteriorate faster) |
| Ignition Harness Inspection | Each 100 hours |
Valve Mechanism
Source: X30010.
| Parameter | Value |
|---|---|
| Valve Type | Overhead, hydraulic valve lifters installed |
| Valve-to-Rocker Clearance (operating, lifters inflated) | 0 (zero — hydraulic lifters self-adjust) |
| Valve-to-Rocker Clearance (lifters deflated) | 0.030 – 0.110 in |
| Valve Lift | 0.410 in |
| Intake Valve Opens | 21° B.T.C. |
| Intake Valve Closes | 58° A.B.C. |
| Exhaust Valve Opens | 65° B.B.C. |
| Exhaust Valve Closes | 14° A.T.C. |
Lubrication System
Source: D971-13, Section 11 (paragraphs 11-8, 11-27, 11-30) and Section 2 (paragraph 2-21, figure 2-4); X30010 (consumption).
| Parameter | Value |
|---|---|
| Oil System Type | Wet sump, pressure lubricating |
| Oil Pump | Engine-driven, gear type |
| Oil Sump Capacity (total) | 6 U.S. quarts |
| Oil Sump Capacity (with external oil filter) | 7 U.S. quarts |
| Normal Operating Capacity (flights under 3 hr) | 5 U.S. quarts |
| Minimum Quantity for Flight | 4 U.S. quarts |
| Additional Oil at Filter Element Change | 1 U.S. quart |
| Average Oil Consumption | ⅓ pint / hour |
| Normal Oil Pressure | 30 – 60 psi |
| Minimum Oil Pressure (idling) | 10 psi |
| Oil Temperature — Normal Operating | Within green arc |
| Oil Temperature Maximum (red line) | 225 °F |
| Full-Flow Oil Filter Hollow Stud Torque | 240 – 300 in-lbs (20 – 25 ft-lbs) |
| Filter Can Out-of-Flat Limit | 0.010 in (replace can if exceeded) |
| Approved Oil Grade — above 40 °F | SAE 40, aviation grade |
| Approved Oil Grade — below 40 °F | SAE 20, aviation grade |
| Oil Specification | Ashless dispersant, Continental MHS-24 |
| Break-In Oil (first 50 hr / until consumption stabilises) | Straight mineral, non-detergent, MIL-L-6082 |
| Oil Change Interval — no external filter | Each 50 hours |
| Oil Change Interval — with external filter | Each 100 hours |
| Filter Element Change Interval | Each 50 hours |
| Oil Change — Calendar Limit | 6 months |
Approved Fuel
Source: D971-13, Section 2, figure 2-4 (Servicing, Sheet 1).
| Parameter | Value |
|---|---|
| Minimum Grade | 80/87 Aviation Grade |
| Alternate 1 | 100/130 Low Lead Avgas — lead content limited to max 2 cc TEL per gallon |
| Alternate 2 | 100/130 Higher Lead Avgas — lead content limited to max 4.6 cc TEL per gallon |
| Alternate Fuel Conditions | Comply with Continental Service Bulletins M74-6 and M75-2 |
| Hydraulic Fluid (airframe) | MIL-H-5606 |
Static Run-Up RPM
Used to diagnose suspected low engine power. Run up at take-off power and mixture settings with the aircraft facing 90° right, then left, to the wind direction; record the RPM in each position and average the results.
Source: D971-13, Section 11, paragraph 11-15D.
| Model Year | Average Static RPM |
|---|---|
| Through 1974 models | 2,550 RPM ± 50 |
| 1975 models onward | 2,510 RPM ± 50 |
If the average is lower than stated, check: carburetor heat control rigging (a partially open control causes slight power loss); magneto timing, spark plugs and ignition harness; induction air filter condition; and perform an engine compression check per the engine manufacturer's manual. Daily changes in atmospheric pressure, temperature and humidity have a slight effect on static run-up.
Component Torque Values
Source: D971-13, Section 11 (engine mount, plug torque); X30010 (plug torque cross-reference); M-0 (plug torque cross-reference).
| Component | Torque Value |
|---|---|
| Spark Plugs | 300 – 360 in-lbs (25 – 30 ft-lbs) |
| Full-Flow Oil Filter Hollow Stud | 240 – 300 in-lbs (20 – 25 ft-lbs) |
| Engine-to-Mount Bolts | 180 – 190 lb-in |
| Engine Mount-to-Firewall Bolts | 100 – 140 lb-in |
The three values above remain open because they are engine overhaul torques. D971-13 is the aircraft service manual and deliberately refers internal engine repair and overhaul to "the applicable publication issued by the engine manufacturer" (paragraph 11-7). They must be taken from the current Continental overhaul manual, not estimated from general fastener tables.
Recommended Nut Torques — Airframe and Installation
Values are in pound-inches and relate only to steel nuts on oil-free cadmium-plated threads. Use the ALT (alternate) column when using AN310 or AN320 castellated nuts and alignment between the bolt and cotter pin slots is not reached at normal torque values — or replace the nut.
Source: D971-13, Section 1, figure 1-4 (Torque Values).
Fine Thread Series
| Tap Size | Tension — STD | Tension — ALT | Shear — STD | Shear — ALT |
|---|---|---|---|---|
| 8-36 | 12 – 15 | — | 7 – 9 | — |
| 10-32 | 20 – 25 | 20 – 28 | 12 – 15 | 12 – 19 |
| 1/4-28 | 50 – 70 | 50 – 75 | 30 – 40 | 30 – 48 |
| 5/16-24 | 100 – 140 | 100 – 150 | 60 – 85 | 60 – 106 |
| 3/8-24 | 160 – 190 | 160 – 260 | 95 – 110 | 95 – 170 |
| 7/16-20 | 450 – 500 | 450 – 560 | 270 – 300 | 270 – 390 |
| 1/2-20 | 480 – 690 | 480 – 730 | 290 – 410 | 290 – 500 |
| 9/16-18 | 800 – 1000 | 800 – 1070 | 480 – 600 | 480 – 750 |
| 5/8-18 | 1100 – 1300 | 1100 – 1600 | 660 – 780 | 660 – 1060 |
| 3/4-16 | 2300 – 2500 | 2300 – 3350 | 1300 – 1500 | 1300 – 2200 |
| 7/8-14 | 2500 – 3000 | 2500 – 4650 | 1500 – 1800 | 1500 – 2900 |
| 1-14 | 3700 – 5500 | 3700 – 6650 | 2200 – 3300 | 2200 – 4400 |
| 1-1/8-12 | 5000 – 7000 | 5000 – 10000 | 3000 – 4200 | 3000 – 6300 |
| 1-1/4-12 | 9000 – 11000 | 9000 – 16700 | 5400 – 6600 | 5400 – 10000 |
Coarse Thread Series
| Tap Size | Tension | Shear |
|---|---|---|
| 8-32 | 12 – 15 | 7 – 9 |
| 10-24 | 20 – 25 | 12 – 15 |
| 1/4-20 | 40 – 50 | 25 – 30 |
| 5/16-18 | 80 – 90 | 48 – 55 |
| 3/8-16 | 160 – 185 | 95 – 100 |
| 7/16-14 | 235 – 255 | 140 – 155 |
| 1/2-13 | 400 – 480 | 240 – 290 |
| 9/16-12 | 500 – 700 | 300 – 420 |
| 5/8-11 | 700 – 900 | 420 – 540 |
| 3/4-10 | 1150 – 1600 | 700 – 950 |
| 7/8-9 | 2200 – 3000 | 1300 – 1800 |
| 1-8 | 3700 – 5000 | 2200 – 3000 |
| 1-1/8-8 | 5500 – 6500 | 3300 – 4000 |
| 1-1/4-8 | 6500 – 8000 | 4000 – 5000 |
Nut types covered. Fine-thread tension STD covers AN310, AN315, AN345, AN363, MS20365, MS21042, MS21044, MS21045 and MS21046. Fine-thread shear STD covers AN316, AN320, MS20364 and MS21245. Coarse-thread tension covers AN363, MS20365, MS21042, MS21043, MS21044, MS21045 and MS21046. Coarse-thread shear covers AN340.
Do not reuse self-locking nuts. These values are recommended for all installation procedures except where other values are stipulated — and they are not to be used for checking the tightness of installed parts during service.
General Fastener Torque Values
Standard torque values for Continental hardware by thread size, from the IO-550 Permold Overhaul Manual, Appendix B. Use only where no component-specific torque value is listed in D971-13 or X30010.
Source: Continental Motors IO-550 Overhaul Manual, Appendix B. NTSB public docket, data.ntsb.gov.
| Bolt / Screw Size | Torque (in-lbs) | Torque (ft-lbs) |
|---|---|---|
| #8-32 | 17.5 – 22.5 | 1.5 – 1.9 |
| #10-32 | 36 – 50 | 3.0 – 4.2 |
| .250-20 | 75 – 85 | 6.3 – 7.1 |
| .250-28 | 90 – 100 | 7.5 – 8.3 |
| .3125-18 | 155 – 175 | 12.9 – 14.6 |
| .3125-24 | 180 – 220 | 15.0 – 18.3 |
| .375-16 | 220 – 260 | 18.3 – 21.7 |
| .375-24 | 275 – 325 | 22.9 – 27.1 |