General Motors 3.0L L4 (181 CID) Engine

⚠ To be performed by qualified personnel only.

1. Before starting engine, check GAIN and STABILITY controls and external SPEED TRIM control are set to mid-position.
2. Crank engine with DC battery power applied. Actuator will energize fully to maximum fuel position until engine starts. Governor should control engine at low idle.
3. If engine unstable after starting, turn GAIN and STABILITY adjustments counterclockwise until engine is stable.
4. Governed speed setpoint increased by clockwise rotation of SPEED adjustment control.
5. At operating speed and no load, rotate GAIN clockwise until instability develops. Gradually move counterclockwise until stability returns. Then move 1/8 turn counterclockwise.
6. Rotate STABILITY clockwise until instability develops. Gradually move counterclockwise until stability returns. Then move 1/8 turn counterclockwise.
7. Gain and stability adjustments may require minor changes after engine load is applied.
8. Dead time compensation can be changed with posts E1, E2, E3. If rapid instability greater than 2Hz at actuator lever, cut jumper between E1 and E2. If still present, remove jumper between E4 and E5. I
9. If throttle is erratic but performance good, removing E4 to E5 jumper will tend to steady throttle.

⚠ Piercing secondary insulation will cause spark plug misfiring and may damage internal conductor.

⚠ Do not connect initial timing connector to B+ while starting engine; may damage ICM.

Tools: Timing light with inductive pick-up or jumper type connectors

1. Do not use timing light that requires piercing secondary insulation. Use only inductive pick-up or jumper type connectors.
2. Install timing light at #1 spark plug lead per manufacturer's instructions.
3. Do not connect alligator clip lead of initial timing connector to B+ source until after engine is started. If connected while starting, ICM in distributor may be damaged.
4. Start engine and allow warm to operating temperature. Connect alligator clip on long lead of initial timing connector to B+ voltage source, such as battery terminal on starter solenoid. This removes a
5. Engine speed should be around 650 RPM. Loosen distributor clamp screw just enough to rotate distributor, and set base timing to specification shown for engine.
6. Industrial do not exceed: 454 initial 6° total 30°; 350 initial 6° total 28°; 262 initial 2° total 26°; 181 initial 0° total 20°.
7. Set idle speed to 700 RPM ± 50 RPM.
8. When timing is set, secure distributor in position with clamp screw. Tighten clamp screw to torque specified.
9. Recheck timing to assure distributor did not move during tightening.
10. Disconnect initial timing connector from B+ source. Label initial timing connector as shown, keeping with engine for future use.

⚠ Only in rare instances should sensitivity adjustment be changed.

Tools: Drill, 1/8\" drill bit, Hoof Seal Kit 200-940

1. Remove plug covering sensitivity adjusting screw by drilling 1/8 diameter hole through center and prying plug out.
2. If engine too sensitive, turn sensitivity screw 1/4 turn clockwise, and readjust main adjustment to desired speed. End each adjustment with clockwise turn.
3. If engine speed drops excessively when loaded, turn sensitivity screw 1/2 turn counter-clockwise, then 1/4 turn clockwise. Readjust main adjustment. End with clockwise turn.
4. After adjustments, seal adjusting screws using Hoof Seal Kit 200-940 or silicone sealer forced into cavity around screw.

⚠ Do not attempt to measure gas pressure with a mercury manometer.

Tools: Water manometer

1. Measure gas inlet pressures at idle and full load with a water manometer. Do not use mercury manometer.
2. If pressures correct, remove air valve cover and lift out spring and air-gas valve with diaphragm.
3. Inspect diaphragm for holes or charring. Diaphragm should be reasonably flexible.
4. Check inside diameter of air valve cup and fins on gas jet for grooves.
5. Inspect inside diameter of gas jet and O.D. of small tapered gas valve for wear.
6. Wash all parts thoroughly in kerosene or equivalent. For digester gas, wash in water and detergent.
7. Reassemble cleaned or replaced parts, centering spring on air valve, and replace cover.
8. From air-fuel outlet of mixer to throttle body, lift valve several times to assure free travel with spring closing valve.
9. Check gas valve for leaks in closed position by sucking on gas inlet. It should be sealed.
10. With engine running at idle, gas pressure should be 5 to 7 inches water column for 1050 BTU natural gas.

1. Drill actuator mounting holes in pre-fabricated bracket. Mount so linkage misalignment is minimal; ball bearing rod ends tolerate max 10 degrees misalignment.
2. Affix actuator bracket to selected location on engine.
3. Attach actuator securely to mounting bracket.
4. Adjust and secure linkage rod and rod end bearings. For linear control, obtain linear relationship between actuator stroke and fuel delivery.
5. For diesel fuel systems, linkage typically linear. Actuator lever nearly parallel to fuel control lever and perpendicular to linkage rod at mid fuel position.
6. For carbureted fuel systems, linkage typically non-linear. Carburetor butterfly valve lever parallel with actuator lever and linkage rod perpendicular to actuator lever at maximum fuel position.
7. Fabricate cable harness to connect speed control unit to actuator. Recommended wire size at least #16 gauge (1.5 mm) for 12V and #18 (1.0 mm) for 24V. Must handle 8 amps for 12V, 4 amps for 24V.
8. For 32V operation, wire as for 24V and add 1.5 ohm, 25 Watt resistor in series with pin A of actuator and output terminal of speed control unit.
9. Connect A and D of military connector or 2 pin connector harness to speed control unit.
10. Push actuator lever to maximum full fuel position. Upon release, linkage should return smoothly to minimum fuel position. Recheck linkage for secure fastening and no binding.

Tools: Hoof Seal Kit 200-481, Hoof Seal Kit 200-940, 1/4\" punch, hammer

1. Remove air cleaner and carburetor after disconnecting throttle linkage, choke cable, spark advance tubing, and fuel line. Discard old gasket and studs.
2. Install long studs, gasket, governor, gasket, aluminum spacer (if needed), gasket, and carburetor. Install drilled brass nut on one carburetor stud.
3. Connect fuel line, choke cable, throttle linkage, and vacuum spark-advance tubing.
4. Check carburetor for smooth throttle action to wide open position and choke control linkage.
5. Start engine, check for fuel and vacuum leaks. Allow engine to warm to normal operating temperature.
6. Adjust governor for required engine speed with carburetor wide open. Turn adjusting screw clockwise for higher speeds, counter-clockwise for lower. End with clockwise turn.
7. Seal governor to engine using seal wire (Kit 200-481) through brass nut, around carburetor body, and through two holes in Hoof Seal Body.
8. Install air cleaner. Road test vehicle and make final speed adjustments as needed. Recheck for fuel or vacuum leaks.
9. Seal governor adjustment with Brass Locking Disc (Kit 200-940) and Expansion Plug tapped with 1/4\" punch.

1. Pull out dipstick, wipe clean and reinsert fully, then withdraw. Oil level should be between marks.
2. If level is at or below lower mark, top with oil immediately, preferably up to upper mark.
3. For sight gauge, oil level should be about 1 1/2 inches down from top of glass when at maximum; verify with dipstick.

⚠ Use soft water. Use of well water or river water may cause scaling or rusting.

⚠ Add anti-corrosive in hot season, anti-freeze in cold season.

1. Open radiator cap and open drain cocks of engine crankcase and radiator to remove coolant.
2. Close drain cocks and pour coolant into radiator. Run engine until coolant heated to about 80°C.
3. If considerable scale or rust, pour in cleaning solution and run engine until solution heated to about 80°C.
4. Continue to idle engine for about 30 minutes.
5. Stop engine, open drain cocks and drain coolant completely.
6. Close drain cocks and pour in coolant to rinse system thoroughly until dirty water no longer runs out.
7. Use soft water and fill until it flows out from overflow pipe.
8. After filling, run engine for awhile. Stop engine, check coolant level and replenish if necessary.

⚠ If left loose, dust will be drawn in and air cleaner will fail to function properly.

1. Remove dust cup and withdraw element. On double element type, do not remove inner element when cleaning outer.
2. Remove inner element only when outer element is replaced; replace both at same time.
3. Clean inside of case and dust cup before installation; slowly insert element.
4. If air cleaner is horizontal, install dust cup so assembling direction mark faces upward.
5. Ensure element and dust cup are securely installed.

⚠ A badly contaminated or deteriorated oil should be replaced regardless of replacement intervals.

⚠ Replace oil filter element each time oil is replaced.

1. After shutdown, remove oil while still hot. Replace oil filter at same time.
2. Install drain plug and pour fresh engine oil from oil filler port up to FULL mark on level gauge.
3. After running engine at idle for several minutes, recheck oil level.

⚠ Wipe away spilt fuel as it could start a fire.

1. Remove element while using care not to spill fuel.
2. Do not wash or reuse element.
3. After installation, bleed fuel system and check for fuel leaks.

⚠ The element cannot be washed and reused.

Tools: Filter wrench

1. Remove element by turning counterclockwise; use filter wrench if hard to loosen.
2. Apply thin coat of engine oil to packing of new element and tighten fully with filter wrench.
3. If only element replaced, replenish oil to proper level and check level.
4. Wipe away spilt oil, start engine, and check for oil leaks from packing.