Usage:
Test the point gap type magneto by the spark at the spark plug. When testing, remember that the magneto output is effected by the condition of the instrument panel components - magnetic switch, stop switch, oil pressure gauge and water temperature gauge. If equipped with overspeed shutoff contactor, and/or gas line valve solenoid, they also are connected with the magneto, and could cause indication of magneto malfunction.
Firing Order
MAGNETO OUTLET NUMBERING DIAGRAMS (SAE Standard Rotation)
MAGNETO OUTLET NUMBERING DIAGRAMS (SAE Opposite Rotation)
Magnetos on SAE Opposite Rotation (clockwise) engines turn in the same direction as those on SAE Standard Rotation (counterclockwise) engines. Direction arrows in the illustrations indicate rotation of magneto distributor disc.
Timing Magneto To Engine
1. Remove the timing pointer cover from right side of the flywheel housing.
2. Rotate crankshaft in direction of engine rotation until No. 1 piston (right bank) is coming up on compression stroke. On compression stroke, both intake and exhaust valves for No. 1 cylinder are closed.
3. Continue rotating crankshaft until desired timing mark appears directly under flywheel pointer. See Chart of Instructions for Timing Magneto to Engine for various conditions such as gas used and compression ratio.
FLYWHEEL TIMING MARKS (TOP CENTER) (View through timing pointer opening)
1-Flywheel pointer.
4. Position the magneto drive slots in the proper position for timing. The drive coupling can be pulled to the rear, then positioned and pushed forward into engagement.
DRIVE SLOT POSITION (Viewed from the rear of the engine)
FLYWHEEL TIMING MARKS 30° BEFORE TOP CENTER (BTC)
2-SAE Standard [(CCW) counterclockwise] rotation G398 and G379 Engines right and left banks. 3-SAE Opposite [(CW) clockwise] rotation G379 Engine right bank. 4-SAE Opposite [(CW) clockwise] rotation G379 Engine left bank. 5-SAE Opposite [(CW) clockwise] rotation G398 Engine left bank.
5. With magneto off the engine, remove timing plug and rotate magneto drive until yellow mark (6) on distributor disc appears in center of opening.
6. Install the top magneto (right bank). The drive tang and slot should be vertical and engage with very little repositioning.
MAGNETO TIMING
6-Distributor disc yellow mark.
7. Rotate crankshaft in direction of engine rotation until No. 12 piston (G398 Engine) or No. 8 piston (G379 Engine) is coming up on compression stroke. On compression stroke both intake and exhaust valve are closed.
8. Repeat Steps 3, 4, and 5. Then install the lower magneto (left bank). The drive tang and slot should be vertical and engage with very little repositioning.
9. Make final adjustment of timing by rotating the magneto at the drive housing mounting and with use of a timing light and jumper wire when the engine is running at any speed.
NOTE: SAE Standard Rotation - Connect timing light to No. 1 spark plug to time the right bank and to No. 12 (12 cylinder) or No. 8 (8 cylinder) spark plug to time the left bank.
SAE Opposite Rotation (clockwise) - Connect timing light to No. 1 spark plug to time the right bank and to No. 4 spark plug (both 12 cylinder and 8 cylinder engines) to time the left bank.
Wiring
The magneto supplies a low voltage alternating current which is stepped up by individual transformers at each cylinder. Since the output polarity alternates, the transformers must be properly wired to provide proper spark plug firing. Connect the magneto as follows:
NOTE: Solder spark plug wires to transformer "U" shaped terminals with acid free solder.
WIRING DIAGRAM
SAE Standard (counterclockwise) Rotation G398 Engine with point gap type magneto.
WIRING DIAGRAM
SAE Opposite (clockwise) Rotation G398 Engine with point gap type magneto.
WIRING DIAGRAM
SAE Standard (counterclockwise) Rotation G379 Engine with point gap type magneto.
WIRING DIAGRAM
SAE Opposite (clockwise) Rotation G379 Engine with point gap type magneto.
Magneto (Fairbanks-Morse)
Removal and Installation
Place identification marks on leads (1) and disconnect them from magnetos (2).
Install magnetos to engine. See topic, TIMING MAGNETOS TO ENGINE.
PREPARING TO REMOVE MAGNETOS (G398 Illustrated)
1-Leads. 2-Magneto.
Disassembly and Assembly
MAGNETO CROSS SECTION
1-Distributor block. 2-Brush and spring assembly. 3-Distributor disc. 4-Nut. 5-Screw. 6-Key. 7-Cam. 8-Lock ring. 9-Bearing. 10-Bearing support. 11-Distributor gear and shaft assembly. 12-Coil. 13-Wedge and screw. 14-Bearing. 15-Outer washer. 16-Key. 17-Setscrew. 18-Contact points. 19-End cap cover. 20-Wire. 21-Impulse coupling. 22-End cap. 23-Support plate. 24-Setscrew. 25-Condenser. 26-Bearing. 27-Screw. 28-Rotor shaft pinion. 29-Rotor shaft assembly. 30-Washer. 31-Lock ring. 32-Inner washer. 33-Seal.
1. Inspect brush and spring assembly (2) in distributor block (1). They should move freely and be under slight spring pressure.
2. Loosen setscrew (17) and remove distributor disc (3). Wipe distributor disc with a clean cloth moistened in petroleum solvent.
3. Remove contact points (18).
4. Remove condenser (25). Clean lead wire and cam. Test for open circuit.
REMOVING END CAP
1-Distributor block. 2-Brush and spring as assembly. 5-Screw (two). 19-End cap cover. 20-Wire. 27-Screw (two).
DISASSEMBLING MAGNETO
3-Distributor disc. 4-Nut. 7-Cam. 17-Setscrew. 18-Contact points. 22-End cap. 25-Condenser.
PREPARING TO REMOVE BEARING SUPPORT
6-Key. 10-Bearing support. 23-Support plate. 24-Setscrew.
NOTE: Cam (7) has two keyslots, one for each direction of magneto rotation. Each keyslot is marked with an arrow denoting direction of rotation. During assembly, engage key (6) with proper keyslot in accordance with direction of magneto rotation. Direction of magneto rotation is counterclockwise (anti-clockwise) for magnetos mounted on side of engine.
5. Remove bearing support screws. Insert a 1/4"-20 NC forcing screw 11/2" long in place of setscrew (24) and remove bearing support (10). During assembly, coat threads of setscrew (24) with shellac. Turn setscrew in until head is flush with bearing support.
NOTE: Distributor gear and shaft assembly (11) has letters "A" (anti-clockwise) and "C" (clockwise) marked on it. During assembly, align the letter denoting direction of magneto rotation with marked tooth (B) on rotor shaft pinion (28). Direction of magneto rotation for side mounted magnetos is anti-clockwise.
REMOVING BEARING SUPPORT
10-Bearing support. 11-Distributor gear and shaft assembly. 12-Coil. 13-Coil wedge and screw. 28-Rotor shaft pinion. 29-Rotor shaft assembly. B-Marked tooth on rotor shaft pinion.
6. Inspect bearing support (10) and bearings (9) and (26). If bearing support or either bearing shows signs of wear, the entire bearing support must be replaced.
7. Distributor gear and shaft assembly (11) can be removed from bearing support (10). Remove lock ring (8) and press from bearing support.
8. Loosen coil wedge and screws (13) and turn rotor shaft assembly (29) until flux lock is broken. Slide coil (12) from housing. Inspect for cleanliness. Test for continuity.
NOTE: Coil (12) has two leads. During assembly, shorter lead should be fastened under left coil wedge screw. Longer lead should be fastened to breaker arm terminal screw.
9. Remove impulse coupling (21).
PREPARING TO REMOVE ROTOR SHAFT ASSEMBLY
15-Outer washer. 16-Key. 21-Impulse coupling. 29-Rotor shaft assembly.
10. Remove outer washer (15) and seal (33) and inner washer (32) beneath it.
11. Remove lock ring (31) and press rotor shaft assembly from housing.
12. Remove washer (30) and press bearing (14) from housing.
13. Inspect all parts.
14. Assemble in reverse order of disassembly.
15. To install rotor shaft assembly (29):
a. Assemble distributor gear and shaft assembly (11) to bearing support (10). Install lock ring (8).
b. Align marked tooth (B) on rotor shaft pinion (28) with tooth marked "A" on distributor gear and shaft assembly (11). All side mounted magnetos are anti-clockwise rotation.
c. Press rotor shaft assembly (29) into bearing support (10).
INSTALLING BEARING SUPPORT AND ROTOR SHAFT ASSEMBLY
d. Install rotor shaft assembly and bearing support as a unit.
e. Press rotor shaft assembly (29) into housing and install lock ring (31), seal (33), and washers (15) and (32). Do not install impulse coupling (21) until edge gap and contact point adjustments have been made.
NOTE: Insert a 3/16" rod 3" long in place of setscrew (24). Press against end of rod to install rotor shaft assembly.
16. Adjust contact points. See topic, CONTACT POINTS.
17. Adjust edge gap setting. See topic, EDGE GAP.
Impulse Coupling
The impulse coupling is installed on the drive end of the magneto. It provides the means for retarding the spark automatically during the starting period and intensifies the spark at low magneto speeds.
PREPARING TO DISASSEMBLE IMPULSE COUPLING
1-Nut and washer. 2-Coupling shell.
1. Grasp one of drive lugs of coupling shell (2) firmly with a pair of pliers. Turn and pull coupling shell at same time until spring (4) releases.
DISASSEMBLING IMPULSE COUPLING
2-Coupling shell. 3-Hub assembly. 4-Spring. A-Anchor slot. B-Spring end.
NOTE: Do not force coupling shell (2) to separate entirely from hub assembly (3). Spring end (B) should first be pried out of slot (A).
2. Pull hub assembly (3) from shaft.
3. Remove spring (4) from coupling shell (2).
4. Inspect all parts.
5. Clean and lubricate before reassembly.
6. Assemble spring (4) to coupling shell (2).
NOTE: Spring (4) must coil in proper direction for magneto rotation. For counterclockwise magnetos, spring (4) must coil clockwise from (B).
7. Position spring end (B) in anchor slot (A).
8. Wind spring one full turn and push coupling shell (2) and hub assembly (3) together.
9. Install coupling shell (2) and hub assembly (3) as a unit to rotor shaft assembly. Install nut and washer (1).
Contact Points
Inspect contact points for mounds, craters, cleanliness, rubbing block or contact wear. Replace if necessary. Points can be cleaned with a petroleum solvent. Oil and grease of any kind must be kept away from the points.
NOTE: The contact points cannot be separated and must be removed and installed as a set.
CONTACT POINTS
1-Breaker arm. 2-Wire. 3-Screw. 4-Wire. 5-Screws.
1. Remove contact point set:
a. Remove screw (3), wire (2) and wire (4).
b. Remove screws (5) and secure contact point set to support plate and remove.
2. Install in reverse order of removal.
NOTE: Do not relubricate cam wick. Replace if necessary.
3. Adjust points to proper opening.
a. Position high point of cam against arm (1).
b. Loosen screws (5).
c. Insert a thickness gauge between points as shown. Point gap should be .017 in. (0,43 mm).
d. Move point set either left or right to obtain proper setting.
e. Tighten screws (5) and recheck setting.
Magneto Edge Gap
Maximum ignition discharge is obtained by interrupting the primary circuit at the instant the primary circuit reaches its maximum value. At this point, the contact points should just be beginning to open.
Field Method
When a setting of edge gap is required to be made in the field without the use of a synchroscope, a temporary setting can be made. This edge gap is set by locking an 1/8" in. (3,175mm) rod between the rotor pole shoe and the housing field.
Adjustment
1. Check contact points and adjust to proper gap.
2. Remove impulse coupling.
3. Turn the rotor shaft so the keyway is up, then turn the shaft approximately 15° in direction of magneto rotation.
EDGE GAP ADJUSTMENT
A-15° angle.
4. View magneto from drive end. Remove setscrew and insert 1/8" rod (4) in timing hole (3). Illustration shows rod (4) inserted in proper hole for counterclockwise rotation magneto.
5. Loosen support plate screws (1).
6. Press rod (4) inward until it contacts rotor. Turn rotor shaft in direction opposite normal rotation until rod locks tight between the rotor pole shoe and housing field.
EDGE GAP ADJUSTMENT
1-Support plate screws. 2-Support plate. 3-Timing holes. 4-Rod.
7. With rotor in this position, move plate (2) either left or right until contact points start to open. Tighten support plate screws (1) securely.
NOTE: The point of initial contact point opening can be determined by inserting a thin piece of cellophane between the points, using a timing light, or a sounding device.
8. Install impulse coupling.
Synchroscope (Shop) Method
The most accurate method of setting the edge gap is with a synchroscope.
Adjustments:
1. Select a coupling that adapts to the tapered and keyed magneto drive shaft and mount the magneto on the synchroscope.
2. Rotate degree disc (1) until 0° is in alignment with pointer (2).
3. Connect a wire (8) between the contact point terminal and a primary terminal of transformer (5).
4. Connect a wire (7) between the other primary terminal on the transformer and the magneto housing (4).
5. Run a high tension wire (3) from the secondary outlet of the transformer to the degree disc on the synchroscope.
MAGNETO AND TRANSFORMER INSTALLED ON SYNCHROSCOPE
1-Degree disc. 2-Pointer. 3-Wire. 4-Magneto housing. 5-Transformer. 6-Wire to contact point. 7-Wire to housing.
6. Drive the magneto in the direction of normal rotation (counterclockwise for both 4 and 6 cylinder magnetos and either engine rotation).
NOTE: Run 4 cylinder magnetos at 1200 RPM and 6 cylinder magnetos at 1800 RPM.
ADJUSTING SUPPORT PLATE
8-Support plate.
7. Adjust the edge gap (contact point opening timing) by rotating the contact point support plate (8) until the spark jumps from the degree disc to the rotating pointer at 15° after 0° in the direction of rotation.
8. Tighten the support plate.
Ignition Transformer
Removal and Installation
1. Disconnect wires from terminals (4).
NOTE: The remaining transformers are removed in a similar manner.
2. Inspect transformers, connections, and terminals for dirt or corrosion. Clean as necessary.
REMOVING IGNITION TRANSFORMER (G398 Illustrated)
1-High tension lead. 2-Ignition transformer. 3-Bolt (two). 4-Terminals.
3. Measure resistance of primary and secondary circuits. Compare the value obtained with that of a transformer known to be good.
4. Install in reverse order of removal.
NOTE: On G379 engines, the positive (+) posts of No's. 1, 7, 8 and 2 transformers are grounded, while the negative (-) posts of No's. 3, 4, 5 and 6 are grounded.
On G398 engines, the positive (+) posts of No's. 1, 3, 5, 8, 10 and 12 transformers are grounded, while the negative (-) posts of No's. 2, 4, 6, 7, 9 and 11 are grounded.
Spark Plugs, Covers And Adapters
Removal and Installation
SPARK PLUG, COVER AND ADAPTER (Cross Section Shown For Better Illustration)
1-Cover. 2-Spark plug. 3-Adapter. 4-Seal. 5-Spacer. 6-Gasket. A-Lip.
Remove the cover (1) from the spark plug (2) and the adapter (3).
NOTE: Do not peel lip (A) from adapter. Grasp the cover by handle and pull upward.
Inspect spark plugs for correct gap and damaged insulation or electrodes. Gap should be .013-.015 in. (0,33-0,39 mm). The use of 1P1790 Firing Indicator can aid in solution of ignition system problems. Put liquid soap on seal groove of adapter (3) and seal (4). Turn adapter into cylinder head to torque of 225 ± 10 lb. ft. (31,1 ± 1,4 mkg) steel adapters and 150 ± 10 lb. ft. (20,7 ± 1,4 mkg) for brass adapters. Install spark plugs to torque of 18 ± 3 lb. ft. (2,5 ± 0,4 mkg).
Instrument Panel
The instrument panel contains a magnetic switch, manual stop switch (1), oil pressure gauge (2) and a water temperature gauge (5), which are connected to the magneto.
In the event of normal stopping, high water temperature or low oil pressure, the magnetic switch is energized and interrupts the magneto output, thus stopping the engine.
Before cranking an engine, the magnetic switch and gauge reset buttons (3) and (4) should be pushed in. This overrides grounding the magneto as is usual in the case of low oil pressure. Normal oil pressure releases the lockout and the gauge switch is ready to signal a shutdown in case of low oil pressure.
When the water temperature gauge switch is operating properly, a hot engine cannot be started until the engine has cooled. Holding in the magnetic switch reset button overrides the oil pressure and water temperature gauge switches.
INSTRUMENT PANEL
1-Stop switch. 2-Oil pressure gauge. 3-Magnetic switch reset button. 4-Oil pressure gauge reset button. 5-Water temperature gauge.
COMPONENT LOCATION (G399 Engine Illustrated)
1. Ignition transformer. 2. Spark plug. 3. Wiring harness. 4. Solid state magneto. 5. Magneto drive housing. 6. Timing bolt.
The solid state ignition system consists of five basic components-a solid state magneto, ignition transformers for each cylinder, wiring harness, spark plugs and engine instrument panel.
CUTAWAY VIEW OF SOLID STATE MAGNETO (Typical Illustration)
Magneto Operation
The solid state magneto is a self-contained electric generating unit. Current is produced in the alternator section of the magneto. Current is stored in the capacitor and released, then distributed through the circuit board in the pulser distributor section. This system uses capacitive storage and low tension distribution.
The solid state magneto utilizes non-wearing electronic switching to handle high surge currents and insures ignition at the highest of combustion chamber pressures. With solid state ignition, energy storage and voltage step up are accomplished separately by the use of electronic switching. This system eliminates breaker points, contactors, and brushes. There is no arcing and only minimum wear. An electromagnetic spark advance is used. An ignition spark of high intensity is produced to fire the air-fuel charge under all operating conditions.
The alternator creates a voltage as the magnet rotor is driven by the engine through a drive coupling. The alternating current is rectified and stored in a capacitor (4). A zener diode, on the power board, regulates the capacitor voltage level for proper firing. As the pulser rotor (8) passes each pulser coil (trigger circuit) (7), a triggering voltage is produced and sent to the electronic switch (silicon-controlled rectifier) (9) the firing cylinder. The switch is then 'turned on' and allows the capacitor (4) to discharge, through the distribution board (5), the low voltage high current impulse to the ignition transformer. In turn, the transformer produces a high voltage low current impulse which is sent across the spark plug electrodes. This same process recurs as the pulse rotor passes each pulser coil.
Magneto Testing And Adjusting
Test the solid state magneto on engine in the same manner as any other magneto, by the intensity of the spark at the spark plug. When testing, remember that the magneto output is effected by the condition of the instrument panel components-magnetic switch, stop switch, oil pressure gauge and water temperature gauge. An overspeed shutoff contactor, and/or gas line solenoid valve connected with the magneto could cause an indication of magneto malfunction. See the topic, Magneto Disassembly for component installation.
Timing Magneto To Engine
Magnetos on SAE Opposite Rotation (clockwise) engines turn in the same direction as those on SAE Standard Rotation (counterclockwise) engines.
Magnetos are available in either clockwise or counterclockwise rotation. These engines require a counterclockwise rotation magneto (CCW) as viewed from the drive end. CCW is stamped on the magneto name plate to identify its proper rotation.
1. Remove the timing pointer cover from the flywheel housing right side.
2. Rotate crankshaft in direction of engine rotation until desired piston is coming up on compression stroke. See Top Center Timing Chart.
Top Center Timing Chart
3. Continue rotating crankshaft until desired timing mark appears directly under flywheel pointer. See Chart of Timing Advance Information for various conditions such as gas used and compression ratio.
Firing Order Chart
CYLINDER NUMBERING SYSTEM
A. Flywheel end. B. Left bank. C. Right bank.
NOTE: After top center (ATC) timing, with engine stopped, is required under some conditions. When flywheels without ATC calibrations are encountered, mark the flywheel on outside diameter by using the same dimensions from the mark portion of the flywheel.
FLYWHEEL TIMING MARKS (Viewed from right side of engine)
1. Flywheel pointer. For G399 Engine right bank (upper) magneto.
FLYWHEEL TIMING MARKS (Viewed from right side of engine)
1. Flywheel pointer. For G379 and G398 Engines.
4. With magneto off the engine, remove timing bolt (8) and rotate magneto drive until yellow mark (drilled hole) on pulser gear appears in center of opening.
5. Position the magneto drive slots in proper position for timing. The drive coupling can be pulled out, then positioned and pushed into engagement.
FLYWHEEL AND MAGNETO TIMING MARKS (All flywheel points indicated are 30° before top center)
2. SAE Standard [(CCW) counterclockwise] rotation G398 and G379 Engines. 3. SAE Opposite [(CW) clockwise] rotation G398 Engine. 4. SAE Opposite [(CW) clockwise] rotation G379 Engine. 5. SAE Standard [(CCW) counterclockwise] rotation G399 Engines right and left bank. Note that at reference (5) where flywheel is marked "6-12 CW," the line marked 30° becomes top center for left bank number 12 cylinder, for SAE Opposite rotation. 6. Top center mark for 1-15, either rotation, also is 30° BTC for SAE Opposite [(CW) clockwise] rotation G399 Engine left bank number 12 cylinder. 7. SAE Opposite [(CW) clockwise] rotation G399 Engine right bank. 8. Timing bolt.
6. Install the magneto. The drive tang and slot should engage.
7. Make final timing adjustment by rotating the magneto at the drive housing mounting and with the use of a timing light when the engine is running at rated speed. Attach timing light to spark plug lead for cylinder indicated in Top Center Timing Chart.
DRIVE TANG AND DRIVE SLOT POSITIONS (Viewed from the rear of the engine)
A. G399 Engine magnetos. B. G379 and earlier G398 Engine magnetos. C. Later G398 magnetos.
Magneto Disassembly
- 2P8338 Holding Fixture
The magneto can be tested to locate defective electrical components. The 2P2340 Magneto Test Bench must be used to make the tests. The Special Instructions GEG02059 is included with the test bench, and covers the test procedure. A partial disassembly of the magneto is required to test the components. Faulty components can be removed and new ones installed as instructed in the following steps.
2P2340 MAGNETO TEST BENCH
1. Remove the magneto from the engine and place it into a 2P8338 Holding Fixture (1). Remove the four screws from the magneto cover (2) and remove the cover.
2. Remove the screw which holds the two black wires to the heat sink cap at (3).
COVER REMOVAL
1. 2P8338 Holding Fixture. 2. Magneto cover.
3. Remove the wires from terminal strip (5), of the distribution board (6). Remove the white and green wires from terminal strip (4) and then remove the cover.
DISCONNECTION OF WIRES
3. Location of black wire connection. 4. Terminal strip. 5. Terminal strip. 6. Distribution board.
NOTE: Remove the capacitor, only if replacement is necessary, by removing the two screws (7) which hold the capacitor (8) to the cover.
CAPACITOR REMOVAL
7. Screws. 8. Capacitor.
4. Melt the solder at joint (9) which holds the wires from the plug connector to capacitor and remove capacitor.
HEATING SOLDER JOINT
9. Joint.
5. Loosen the screws of terminal strip (4) and remove the wires. See the wiring diagrams to reconnect at assembly.
DISTRIBUTION BOARD REMOVAL
4. Terminal. 10. Distribution board. 11. Heat sink cap.
6. Remove the four screws (10) that hold the distribution board to the cap (11). Remove the distribution board and the heat sink cap.
7. Remove the two screws (14) that hold the diode to the heat sink (12). Remove the diode (13). Remove the heat sink (12).
DIODE AND HEAT SINK REMOVAL
12. Heat sink. 13. Diode. 14. Screws.
| NOTICE |
|---|
Pull the heat sink (12) straight out from the magneto. Do not move the heat sink in any direction except straight out. Damage may result to parts of the power board. |
NOTE: Remove the resistor only if replacement is necessary.
8. Loosen the two screws that fasten the resistor wires to terminal strip (17). Remove the wires from terminal strip. See the wiring diagrams to reconnect at assembly.
9. Remove the two screws (15) that hold the resistor (16) to the heat sink. Remove the resistor.
10. Loosen the screws for all the wires at terminal strip (18). Remove all the wires that are not fastened to the heat sink.
RESISTOR REMOVAL
15. Screws. 16. Resistor. 17. Terminal strip. 18. Terminal strip.
11. Loosen the screws at terminal strip (17), for the wires which are not fastened to the heat sink. Remove the wires.
12. Remove the screw which fastens the wires to the heat sink and remove the wires.
13. Cut the cable tie (19) that holds the wires together. Remove the heat sink from the magneto.
HEAT SINK REMOVAL
17. Terminal strip. 19. Cable tie.
14. Loosen the screws on terminal strip which hold the two wires (20) from the heat sink and remove the wires.
SEPARATING HEAT SINK AND POWER BOARD
20. Two wires. 21. Screws.
15. Remove the four screws (21) which hold the power board to the heat sink, and remove the power board.
16. Remove the four screws (23) and remove the plate (22).
17. Remove nut (24) and washer which fasten the pulser rotor (25) to the shaft. Remove the rotor.
NOTE: The rotor illustrated is for counterclockwise magnetos. The "A" mark stamped on the rotor indicates this and "C" mark indicates clockwise.
PLATE REMOVAL
22. Plate. 23. Screws.
PULSER ROTOR REMOVAL
24. Nut. 25. Pulser rotor.
18. Remove the two screws (26) from the center of the pulser coil (27). Remove the two screws from the lower edge of the pulser coil. Remove the pulser coil.
NOTE: At assembly be sure to use the pulser coil that matches the magneto specifications.
PULSER COIL REMOVAL
26. Screws. 27. Pulser coil.
PULSER COILS
A. G379 Engine, counterclockwise rotation odd firing magneto, pulser coil. B. G399 Engine, counterclockwise rotation, even firing magneto pulser coil.
PULSER COIL
C. G398 Engine, counterclockwise, even firing magneto pulser coil.
19. Remove the nut (29) which fastens the drive coupling (28) to the shaft. Remove the drive coupling from the shaft. Remove the key from the shaft.
PREPARING TO REMOVE DRIVE COUPLING
28. Drive coupling. 29. Nut.
20. Remove the first washer (30), seal (31) and second washer (30) from the shaft.
SEAL REMOVAL
30. Washer. 31. Seal. 32. Snap ring.
21. Remove the snap ring (32) from the shaft.
22. Remove the four screws (33) which hold the end cap (34) to the alternator housing of the magneto. Remove the three screws (35) from the support (36) for bearing.
BEARING SUPPORT REMOVAL
33. Screws. 34. End cap. 35. Screws. 36. Support.
23. Remove the bearing support and magneto rotor assembly from the alternator housing (37).
PRESSING ROTOR SHAFT FROM BEARING
37. Alternator housing.
REMOVING ROTOR AND DISTRIBUTOR GEAR
36. Support. 38. Rotor. 39. Gear.
24. Remove the magnetic rotor (38) from the support (36) for bearing, then remove the snap ring from the shaft of the distributor gear and remove the distributor gear (39) from the bearing support.
NOTE: At assembly put the mark on gear of the magnetic rotor in alignment, with the correct mark of the distributor gear. "A" mark is for counterclockwise, "C" mark is for clockwise rotation of Magneto. Install magnetic rotor in the bearing support.
BEARING REMOVAL
40. Snap rings.
COIL REMOVAL
41. Coil. 42. Wedges.
25. Remove the two snap rings (40) which hold the bearings in the bearing support. Remove the bearings from the support.
26. Remove the two screws that fasten the wedges (42) to the housing. Remove the wedges. Remove the coil (41) from the housing.
27. Remove the screw (44) that fastens the retainer (43) for bearing to the housing. Remove the bearing retainer. Remove the bearing from the housing.
BEARING REMOVAL
43. Retainer. 44. Screw.
28. Assemble in the reverse order of disassembly.
Ignition Transformers
The ignition transformer step up the magneto voltage to the high voltage required to fire the spark plugs. For good operation, the terminals must be clean and tight. The transformer terminal marked + (positive) is connected by a wire to the capacitor for each cylinder and the magneto plug connector marked "L" for the right bank and "K" for the left bank except on G379 Engines, SAE opposite rotation which have right bank connected to "K" and left to "L".
TRANSFORMER
| NOTICE |
|---|
Do not pierce the insulation on the high voltage wire to the spark plug. A hole in the insulation will cause misfiring. |
Spark Plugs And Adapters
Natural gas engine spark plugs use a dual ground electrode. This allows the spark plug to run longer before it needs to be regapped or replaced.
The boot covers the high tension lead and the terminal portion of the spark plug. This prevents water, dirt and other foreign material from getting into the spark plug adapter.
SPARK PLUG AND ADAPTER
1. Boot. 2. High tension wire. 3. Seal. 4. Spark plug adapter. 5. Spark plug.
Assembly
If the spark plug adapter is incorrectly seated, water leakage or detonation and preignition can occur. Adapters are installed and removed with use of an 8S7227 Wrench.
Spark plug firing voltage will vary with the spark plug condition and engine load. A new spark plug in an idling engine will take 3,000 to 6,000 volts to fire. At full load, this voltage will be 8,000 to 10,000 volts. When the spark plug is worn to the regap time interval, the firing voltage will be over 10,000 volts. Running the plugs past regap time, will cause firing voltage to go even higher. When the spark plug requirements exceed this value, that spark plug begins to fire erratically.
Spark plug gap should be maintained at .013 to .015 in. (0,335 to 0,385 mm). The use of 1P1790 Firing Indicator can assist in solving ignition problems. Follow the instructions included with the tool.
Coat seal groove of adapter and seal with liquid soap. Install adapter (1) into cylinder head and tighten to torque of 225 ± 10 lb. ft. (31,1 ± 1,4 mkg) for steel adapters and 150 ± 10 lb. ft. (20,7 ± 1,4 mkg) for brass adapters. Spark plugs (3) should be installed to a torque of 18 ± 3 lb. ft. (2,5 ± 0,4 mkg) with 1P7424 Spark Plug Socket (4).
SPARK PLUG INSTALLATION
1. Adapter. 2. 3/8 in. Drive extension. 3. Spark plug. 4. 1P7424 Spark Plug Socket.
Instrument Panel
The instrument panel contains a magnetic switch, manual stop switch (1), oil pressure gauge (2), and a water temperature gauge (5) which are connected to the magneto. The safety-shutoff gas supply line valve attachment is also operated by the instrument panel upon shut down.
In the event of normal stopping, high water temperature or low oil pressure, the magnetic switch is energized and interrupts the magneto output, thus stopping the engine. On solid state systems a different magnetic switch is required to carry the higher output of the magneto.
Before cranking a cold engine, the magnetic switch and oil pressure gauge reset buttons (3) and (4) should be pushed in. This overrides grounding the magneto as is usual in the case of low oil pressure. Normal oil pressure releases the lock out and the gauge switch is ready to signal a shut down in case of low oil pressure.
INSTRUMENT PANEL
1. Stop switch. 2. Oil pressure gauge. 3. Magnetic switch reset button. 4. Oil pressure gauge reset button. 5. Water temperature gauge.
When the water temperature gauge switch is operating properly, a hot engine cannot be started until the engine has cooled. Holding in the magnetic switch reset button will override the oil pressure and water temperature gauge switches.
The safety shut off gas line valve attachment requires manual resetting after shut down to open the gas supply.
WIRING DIAGRAM WITH OVERSPEED CONTACTOR AND REMOTE MOUNTED GAS VALVE
Gauge Contact Point Adjustment
The oil pressure gauge contact should be adjusted to shut down the engine at 8 psi (0,56 kg/cm2) oil pressure. Water temperature gauge contact should be adjusted to shut down the engine at 210° F (99° C).
Both gauges adjust in the same manner. Position the adjusting screw so the indicator just touches it at the required value.
WATER TEMPERATURE GAUGE
1. Adjustment screw.
Wiring Diagrams
The diagrams are the same for systems with earlier and later magnetos, except that the capacitor at each transformer is not used with the later Air Gap Magnetos.
G398 Engine-SAE Opposite Rotation ignition distribution system with solid sate magneto.
G398 Engine-SAE Standard Rotation ignition distribution system when equipped with solid state magneto.
G379 Engine-SAE Standard Rotation ignition distribution system when equipped with solid state magneto.
G379 Engine-SAE Opposite Rotation ignition distribution system with solid state magneto.
G399 Engine-SAE Opposite Rotation ignition distribution system with solid state magneto.
G399 Engine-SAE Standard Rotation ignition distribution system when equipped with solid state magnetos.
12 CYLINDER AIR GAP MAGNETO DIAGRAM
1. Pulser coil. 2. Terminal strip (upper on power board). 3. Distribution board. 4. Terminal strip (upper on distribution board). 5. Terminal strip (lower on power board). 6. Power board. 7. Terminal strip (lower on distribution board). 8. Plug connector. 9. Generator coil. 10. Capacitor. 11. Terminal strip (on auxiliary distribution board). 12. End cover. 13. Auxiliary distribution board.
8 CYLINDER AIR GAP MAGNETO DIAGRAM
1. Pulser coil. 2. Terminal strip (upper on power board). 3. Distribution board. 4. Terminal strip (upper on distribution board). 5. Terminal strip (lower on power board). 6. Power board. 7. Terminal strip (lower on distribution board). 8. Plug connector. 9. Generator coil. 10. Capacitor. 11. End cover.
Introduction
The illustrations and information in these instructions cover diesel engine applications specifically. Natural Gas Engine applications are also covered to a large extent, because the governor actuating mechanism is the same for either application.
The desired speed of the engine is selected by the operator. The governor tends to maintain the engine speed selected by the operator. The Hydra-Mechanical governor, located in the Vee of the engine, is mounted on the top of the fuel pump and governor drive housing.
Governor Seal (Diesel Engines)
The mounting bolt on idle speed adjustment cover (2) and a mounting bolt on fuel ratio control (3) are sealed with a wire and an aluminum seal (1). In order to remove either the fuel ratio control or the idle speed adjustment cover, the wire seal must be broken.
GOVERNOR SEAL
1-Seal. 2-Idle speed adjustment cover. 3-Fuel ratio control.
Rack settings are carefully set at the factory and should not be changed without specific instructions to do so. An incorrectly adjusted fuel rack affects the operation of the turbocharger. See the topic, TURBOCHARGER ALTITUDE OPERATION.
Operation And Lubrication
Basic Governor Operation
The governor controls engine speed by balancing governor spring force with governor weight centrifugal force. The compressed governor spring force is applied to increase the supply of fuel to the engine, while the centrifugal force of the engine driven governor weights is applied to decrease fuel to the engine.
The governor is supplied with engine oil through the fuel pump and governor drive housing oil manifold (A). Drilled passages (B) supply oil to the governor upper housing and reservoir. The oil reservoir in the governor drive housing maintains a supply of oil for the gear type oil pump (C). The pump delivers 1.5 U.S. GPM (5,68 lit/min) at engine speed of 1200 RPM and supplies oil at 100 PSI (7,0 kg/cm2) to the governor actuating mechanism.
GOVERNOR OIL PUMP SUPPLY
A-Oil manifold. B-Drilled passages. C-Oil pump.
When the engine is operating, the balance between the centrifugal force of revolving weights (10) and the force of spring (9) controls the movement of valve (13). The valve directs pressure oil to either side of positioning piston (15). Depending on the position of the valve (13), piston (15) will move pin (22) to increase or decrease fuel to the engine to compensate for load variation.
Pressurized lubrication oil enters passage (17) in the governor cylinder (18). The oil encircles sleeve (16) within the cylinder. Oil is then directed through a passage (14) in piston (15) where it contacts valve (13).
When engine load decreases, engine RPM increases, revolving weights (10) speed up, and the toes on the weights move valve (13) toward the fuel-off direction to allow the oil behind piston (15) to flow through a drain passage at the top of piston (15). At the same time, the pressure oil between sleeve (16) and piston (15) forces the piston and pin (22) to decrease the amount of fuel to the engine. Engine RPM decreases until the revolving weights balance the force of the governor spring.
When engine load increases, engine RPM decreases and revolving weights (10) slow down. The weights move toward each other and allow governor spring (9) to move valve (13) toward fuel on direction. As the valve moves, an oil passage around it opens to pressure oil. Oil then flows through passage (14) and fills the chamber on spring side of piston (15). The pressure forces the piston and linkage to increase the amount of fuel to the engine. Engine RPM increases until the revolving weights rotate fast enough to balance the force of the governor spring.
GOVERNOR CROSS SECTION-RIGHT SIDE VIEW
1-Fuel rack adjustment screw. 2-Shutoff shaft. 3-Collar. 4-Oil passage to speed limiter plunger. 5-Torque spring (rack stop). 6-Bolt. 7-Lever. 8-Spring seat. 9-Governor spring. 10-Governor weights. 11-Seat. 12-Thrust bearing. 13-Valve. 14-Oil passage. 15-Piston. 16-Sleeve. 17-Oil passage. 18-Cylinder. 19-Governor drive housing. 20-Oil pump. 21-Governor drive shaft. 22-Pin assembly. 23-Lever. 24-Fuel rack.
When the engine is started, the speed limiter plunger restricts the movement of the governor control lever (7). This limits engine speed to approximately 900 RPM. When operating oil pressure is reached, the plunger in the speed limiter retracts and the governor control can be moved to the HIGH IDLE position. The HIGH IDLE speed is limited by the high idle adjustment screw within the governor which limits the fuel on travel of lever (7).
On diesel engines the LOW IDLE speed is controled by the low idle adjustment screw detent which limits fuel off travel of the control lever (7). Overriding the detent will stop the engine.
On natural gas engines, when engine RPM is at LOW IDLE, an adjusting screw bears against a stop at the carburetor. To stop the engine, the magneto is grounded.
Oil from the engine lubrication system lubricates the governor weight bearing. The various other parts are splash lubricated. Oil from the governor drains into the fuel pump and governor drive housing.
Governor Disassembly And Assembly - (Earlier Type Diesel Governor Illustrated)
PREPARING TO REMOVE GOVERNOR
1-Air line. 2-Governor linkage assembly. 3-Bolts (six). 4-Pressure gauge oil line. 5-Oil line to oil pressure shutoff. 6-Governor.
Install a new gasket and align oil hole (8) with passage in housing.
When installing the governor, the governor drive shaft spline will readily mesh with governor drive gear (9). On diesel engines, fuel rack (7) must be positioned to allow the governor fuel rack control lever to fit in the slot on the fuel rack.
PREPARING FOR GOVERNOR INSTALLATION
7-Fuel rack. 8-Oil hole. 9-Governor drive gear.
NOTE: After the governor is installed on the diesel engine, make certain the governor can control the fuel rack. See the topic FUEL RACK SETTING.
Governor Disassembly And Assembly Earlier Type - (Diesel Governor Illustrated)
Governor Housing Disassembly
1. Remove the governor. See covering topic.
PREPARING TO REMOVE TOP PLATE
1-Fuel ratio control. 2-Bolts (eight). 3-Idle RPM adjustment screw cover. 4-Top plate.
2. Carefully remove cover assembly (9). The forked end of lever (11) is positioned under collar (10).
NOTE: Loosen the nut on the end of contact screw (7) before removing cover assembly (9). After the cover assembly is installed and the nut tightened, the head end of the contact screw must be against contact (12).
PREPARING TO REMOVE COVER ASSEMBLY
5-High idle adjustment screw. 6-Bolt. 7-Contact screw. 8-Low idle adjustment screw. 9-Cover as assembly. 10-Collar. 11-Lever (on engine shutoff control shaft).
NOTE: Contact (12) is positioned between the retainer and the torque spring. If the governor is equipped with only a stop bar, contact (12) is positioned between the retainer and the stop bar.
3. If it is necessary to remove the speed limiter plunger, remove plug (14), the spring and the plunger from the housing.
4. Drive needle bearings and shaft (16) thru governor drive housing (18). The internal lever on shaft (16) is a slip fit on the shaft in diesel engines and keyed and clamped in gas engines. At assembly, shaft (16) should have .02-.06 in. (0,5-1,5 mm) end play.
GOVERNOR HOUSING
12-Contact. 13-Spring collar. 14-Plug. 15-Spring.
5. Disengage the rack control lever from between spring loaded sleeve (17) and collar at end of pin assembly.
6. Remove the governor drive housing (18) from the governor housing.
PREPARING TO REMOVE THE GOVERNOR DRIVE HOUSING
16-Shaft and bearings. 17-Spring loaded sleeve. 18-Governor drive housing.
NOTE: The actuating mechanism and oil pump will remain with the governor drive housing (18).
CONTROL MECHANISM REMOVAL
19-Bolt. 20-Governor spring and seat. 21-Shaft. 22-Lever.
7. Drive the pin (23) from lever (22) and remove spring (24) and plunger (25).
CONTROL LEVER DISASSEMBLY
22-Lever. 23-Pin. 24-Spring. 25- Plunger.
Governor Actuating Mechanism and Oil Pump
1. Remove the oil pump and governor drive mechanism from the governor drive housing by applying a light force after removing bolts and locks (23).
2. The governor drive shaft, pump cover (20) drive gear (19) and actuating mechanism drive gear (17) can be removed as a unit from the actuating mechanism.
GOVERNOR ACTUATING MECHANISM AND OIL PUMP-CROSS SECTION
1-Bolt. 2-Coned disc spring. 3-Spring seat. 4-Weight assembly. 5-Washers. 6-Spring. 7-Retaining ring. 8-Dowel. 9-Thrust bearing. 10-Sleeve. 11-Snap ring. 12-Piston. 13-Valve. 14-Snap ring. 15-Sleeve. 16-Cylinder. 17-Actuating mechanism drive gear. 18-Seal. 19-Oil pump drive gear. 20-Oil pump cover. 21-Pin assembly. 22-Oil pump idler gear bearing.
PREPARING TO REMOVE ACTUATING MECHANISM
2-Coned disc spring. 3-Spring seat. 7-Retaining ring. 8-Dowel. 20-Pump cover. 23-Bolts (five) and locks.
3. Remove coned disc spring (2).
NOTE: Coned disc spring (2) is a bumper spring and must be installed with the convex face toward spring seat (3).
4. Remove sleeve (15) and unlatch pin assembly (21) from piston (12). At assembly, inspect seal (18) and lubricate it with ball and roller bearing lubricant.
5. Remove snap ring (14) and cylinder (16).
6. Remove retaining ring (7), dowel (8) spring seat (3) and valve (13).
NOTE: If either piston (12) or valve (13) is damaged, install a new matched set.
7. Remove sleeve (10), washers (5), spring (6) and bolt (1) from spring seat (3).
8. Remove snap ring (11) and thrust bearing (9) from sleeve (10).
NOTE: At assembly lubricate all parts with clean crankcase lubricating oil.
GOVERNOR ACTUATING MECHANISM AND OIL PUMP
17-Actuating mechanism drive gear. 19-Oil pump drive gear. 20-Pump cover.
GOVERNOR DRIVE HOUSING
22-Oil pump idler gear bearing. 24-Oil pump pressure regulating valve. 25-Governor drive housing.
9. Pull governor actuating mechanism drive gear from drive shaft with 8B7548 Push Puller with 8B7550 Legs, 8H663 Bearing Pulling Attachment, 8B7560 Step Plate and 8H684 Heavy-Duty Ratchet. See GENERAL INSTRUCTIONS.
NOTE: At assembly tighten drive gear retaining 3/8 in. bolt to torque of 36-48 lb. in. (41,5-55,3 cm.kg) and earlier 1/4 in. nut to torque of 6-12 lb. ft. (0,83-1,66 mkg).
10. If it is necessary to replace oil pump idler gear bearing (22) limit its driving so it extends .465-.475 in. (11,81-12,06 mm) above the bottom of the pump bore.
11. The oil pump pressure regulating valve (24) is located on the right side of the governor drive housing (25) for SAE Standard Rotation engines. The valve is interchanged with the plug on the left side of the SAE Opposite Rotation engines.
Adjustments
High and Low Idle Speeds
The engine idle speed can be checked at the tachometer drive housing, located on the safety shutoff housing, on the fuel pump and governor drive housing. Remove the cap and insert a hand tachometer as shown. The reading observed will be one-half engine speed.
Remove cover (4) from the top of the governor and adjust the high and low idle speeds.
To increase the high and low idle speeds turn the adjusting screws (1) and (3) counterclockwise. Screw (1), which is nearest the front of the governor, adjusts the high idle speed and screw (3) adjusts the low idle speed. Holes (2) in cover (4) are serrated. The cover prevents the screws from turning after the cover is installed.
After setting the idle speed, move the governor control lever to increase the engine speed. Return it to the desired idle position and recheck the idle speed. Repeat this procedure and if necessary readjust the idle speeds until the desired idle speeds are obtained.
CHECKING ENGINE IDLE SPEED
NOTE: The gas engines require a low idle stop setting at the carburetor.
GOVERNOR ADJUSTMENTS
1-Screw. 2-Retainer holes. 3-Screw. 4-Cover.
Fuel Rack Setting
- 9S227 Bracket Group.8S2283 Dial Indicator.8S4627 Circuit Tester.8S3675 .125 in. Contact Point.9S8521 Rod.9S8519 Plug.
9S240 RACK POSITIONING TOOLS TO CHECK FUEL RACK SETTING
1-9S8519 Plug and 9S8521 Rod. 2-9S227 Bracket Group with spacer. 3-8S4627 Circuit Tester. 4-8S2283 Dial Indicator with 8S3675 Point.
Refer to RACK SETTING INFORMATION for the correct rack setting dimension.
Refer to Special Instruction (GEG00231) for detailed instructions for use of tools required to check and adjust the fuel rack setting.
To change the adjustment, loosen locknut on adjusting screw (5) and turn the screw. Tighten locknut to 11 ± 1 lb. ft. (1,55 ± 0,15 mkg) and again check the adjustment.
TOOLS IN PLACE FOR DEPRESSING SPEED LIMITER
5-Rack setting adjusting screw. 6-Governor control lever. 7-9S8519 Plug and 9S8521 Rod.
When equipped with a fuel ratio control, it should be adjusted at installation. The 8S4627 Circuit Tester set up should remain on the engine until the fuel ratio control adjustment is made.
TOOLS IN PLACE FOR RACK SETTING
8-Insulated contact screw. 9-8H8518 Wrench (11/4 in. operating rack shutoff lever). 10-8S4627 Circuit Tester.
Gas Engine Hydra-Mechanical - Governor Adjustments
Stop Collar Screw Adjustment
- 9S225 Bracket2H191 Bolt8S2283 Dial Indicator9S8883 Contact Point
The stop screw in the stop collar on later governors should be adjusted to limit the collar travel to .605 in. (15,849 mm).
Remove the linkage from governor terminal shaft lever (3) and remove governor cover. Fasten 9S225 Bracket (1) with 2H191 Bolt as shown and install 8S2283 Dial Indicator. Measure the maximum movement of stop collar (2) from fuel full on to fuel off positions. To do this, make dial indicator readings when both levers and collar are in the same relative positions, fuel full on (stop collar on stop) and full off (stop collar raised). Lift the stop collar by hand in the fuel off direction, gently against the resistance of the wave washer. Adjust the stop screw and tighten the locknut to torque of 11 ± 1 lb. ft. (1,52 ± 0,14 mkg) and check the adjustment.
TOOLS IN PLACE FOR STOP SCREW ADJUSTMENT
Linkage Adjustments
All illustrations have same reference numbers for parts involved in these adjustments. Dimensions in inches (mm).
Illustrated here are three basic usages of the 1P2385 Protractor Tool.
First-Vertical housing face-to-lever angle.
Second-Horizontal or level-to-lever angle.
Third-Lever-to-lever angle.
1P2385 PROTRACTOR TOOL USAGE
A-Angle setting indicator. B-Protractor plate edge aligned with lever. C-Vertical housing face and extension arm alignment. D-Level bubble. E-Angle setting indicator. F-Extension arm aligned with lever. G-Extension arm aligned with lever. H-Plate edge aligned with second lever. I-Angle setting indicator.
Earlier Engines
1. Assemble end levers (2) and (7) to cross shaft at angles shown from center lever (1).
2. With throttle plates closed, assemble carburetor levers (5) and (8) on carburetor throttle shaft at angles from horizontal as shown.
3. Position center lever at angle to vertical as shown. Then adjust and assemble rods (6) and (9) with both throttle plates in the CLOSED position.
4. Open the throttle plates to check proper positioning of levers. This will increase angle of center lever (1) from 25° on G398 and G379 Engines right side (G379 Engine left side angle decreases from 25°). On G399 Engines angle increases from 15°.
5. With governor at SHUTOFF position, governor lever (3) horizontal, adjust and assemble the rod (4) from center lever (1) to the governor and maintain the angle of the center lever.
6. Make necessary carburetor and gas regulator adjustments. See covering topic.
Parts are: 1-Center lever. 2-Right end lever. 3-Governor lever. 4-Governor to center lever rod. 5-Carburetor lever. 6-End lever-to-right carburetor lever rod. 7-Left end lever. 8-Carburetor lever. 9-End lever-to-left carburetor lever rod.
Later Engines
LATER ENGINE CONTROL LINKAGE
Effective with G399-49C173-Up, G398-73B796-Up, G379-72B404-Up.
1. Assemble end levers (2) to cross shaft at angle of 135° from center lever (1) as shown.
2. With throttle plates closed, assemble carburetor levers (5) and (7) on carburetor throttle shaft at 45° angles from horizontal as shown.
3. Position center lever (1) vertically and adjust and install rods (6) with both throttle plates in the CLOSED position.
4. Open the throttle plates to check proper positioning of levers.
5. With governor lever (3) at SHUTOFF position, adjust and install rod (4) between center lever (1) and governor lever (3) while still maintaining the vertical position of center lever.
6. Make necessary carburetor and gas regulator adjustments. See covering topics.
Fuel Ratio Control
Operation
The fuel ratio control coordinates the movement of the fuel rack with the amount of air available in the inlet manifold, keeping exhaust smoke to a minimum.
Later controls have a manually operated override lever (1) to allow unrestricted rack movement during cold starts. After the engine starts, the override automatically resets in the RUN position.
Collar (6) mechanically connects with the fuel rack, as explained in the topic, BASIC GOVERNOR OPERATION. The head of bolt assembly (7) latches through a slot in collar (6). An air line joins the chamber above diaphragm (5) with the air in the engine inlet manifold.
FUEL RATIO CONTROL CROSS SECTION
1-Lever. 2-Housing. 3-Spring. 4- Spring. 5-Diaphragm. 6- Collar. 7-Bolt assembly.
When the operator moves the governor control to increase engine RPM, the governor spring moves collar (6) contacting the head of bolt assembly (7). The bolt assembly restricts the movement of the collar until spring (3) and the turbocharger boost of air pressure in the cover forces diaphragm (5), spring (4) and bolt assembly (7) to relieve the bolt head restriction to collar (6). This will allow the fuel rack to move toward more fuel position as turbocharger air pressure increases with the increase in engine RPM. The characteristics of springs (3) and (4) are such that a balance is maintained between increase of fuel, increase of load, increase of engine RPM and increase of air for combustion in the engine. The system stays in balance to assure minimum smoke and give maximum engine acceleration or load acceptance.
Removal and Installation - (Earlier Type Controls Illustrated)
PREPARING TO REMOVE FUEL RATIO CONTROL
1-Wire seal. 2-Bolts (two). 3-Air line.
REMOVING FUEL RATIO CONTROL
4-Fuel ratio control. 5-Bolt. 6-Slot.
Unlatch bolt (5) from the slot (6) of collar (hook on earlier governors) in the governor and remove fuel ratio control (4).
Install new gasket if necessary.
NOTE: When assembling, move the governor control lever to fuel off position, then latch bolt (5) in the slot (6) and install bolts (2).
Install a new wire seal (1) and make certain air line (3) connection will not leak air.
Disassembly and Assembly
Remove the fuel ratio control from the governor. See the covering topic.
1. Remove bolts (1) and top cover (2).
2. Remove bolts (6), cover (4) and spring (5).
3. Bolt assembly (13), washer (7), diaphragm (9) and retainer (8) are removed from housing (11) as a unit.
FUEL RATIO CONTROL-CROSS SECTION
1-Bolts (three). 2-Top cover. 3-Gasket. 4- Cover. 5-Spring. 6-Bolts (two). 7-Washer. 8- Retainer. 9-Diaphragm. 10-Spring. 11- Housing. 12-Bushing. 13-Bolt assembly.
NOTE: Bushing (12) is part of housing (11).
4. Remove washer (7) from bolt assembly (13).
5. Diaphragm (9) is removed after bolt assembly (13) is unscrewed from retainer (8).
NOTE: If gasket (3) and/or diaphragm (9) are damaged, install new parts.
6. Reassemble in reverse order of disassembly.
NOTE: When installing cover (4) make certain the outer edge of diaphragm (9) is in the groove in the face of the cover.
Fuel Ratio Control Test and Adjustment
Override Control Lever-Bench setting adjustment is made in the following manner:
OVERRIDE CONTROL LEVER ADJUSTMENT
1-Control lever. 2-Screw. 3-Nut.
1. Place lever (1) in start position.
2. Loosen locknut (3) and turn adjusting screw (2) counterclockwise as far as necessary to cause the lever to snap to run position when bolt (4) is pulled against the large spring pressure. Approximately 40 lbs. (18,1 kg) pull is required to move the bolt.
3. Tighten the locknut.
CHECKING OVERRIDE CONTROL LEVER ADJUSTMENT
4-Bolt in vise.
Diaphragm-Bench test should be made with shop air pressure applied to the chamber above the diaphragm through port (5) in cover.
1. Application of 5 PSI (0,35 kg/cm2) to chamber (6) should start movement of bolt (4).
2. Application of 16.5-20.5 PSI (1,16-1,44 kg/cm2) pressure causes bolt (4) to be fully extended.
3. Pressure of 35 PSI (2,46 kg/cm2) applied in the chamber (6) and turned off should drop no more than 2 PSI (0,14 kg/cm2) in 10 seconds.
TESTING DIAPHRAGM
4-Bolt. 5-Port. 6-Chamber.
Fuel Ratio Control Setting
- 8S4627 Circuit Tester
The fuel rack must be set correctly before setting the fuel ratio control. The same 8S4627 Circuit Tester set up can be used as for fuel rack setting. See the topic, FUEL RACK SETTING.
Install the fuel ratio control when the governor control lever is in the fuel off position. Then the governor control lever should be moved to the high idle position, with engine stopped, through the remainder of the setting procedure. Be sure the speed limiter is depressed.
1. Remove the override control mechanism and cover.
2. Turn the cover (1) clockwise until the circuit indicator light glows brightly.
SETTING FUEL RATIO CONTROL
1-Cover. 2-Bolt.
3. Turn the cover counterclockwise slowly until the indicator light flickers. This should place the rack in fuel rack setting position. Mark a reference line on the cover and base for adjusting purposes.
NOTE: In this application, one revolution counterclockwise of the cover causes .090 in. (2,29 mm) restriction in movement of the rack. Six holes in the cover for the mounting bolts, allows for an additional adjustment of .015 in. (0,38 mm) between holes as related to rack movement in this application.
4. Turn the cover counterclockwise the number of turns plus any fraction for closer hole alignment, to arrive at the dimension closest to that given in the RACK SETTING INFORMATION.
5. Install the cover, override mechanism and remove the rack setting tools.
NOTE: Before starting the engine, make certain the governor control lever will move the governor to the SHUTOFF position and that all parts operate freely.
With the above initial adjustment made, a further adjustment can be made while the engine is running (if necessary) to improve engine performance. To reduce exhaust smoke during acceleration, turn cover (1) out (less fuel) 1/2 turn at a time until satisfactory. When exhaust smoke is acceptable but acceleration is sluggish, turn cover (1) in (more fuel) 1/2 turn at a time until satisfactory.
NOTE: Some exhaust smoke is likely to appear at maximum acceleration.
If acceleration is sluggish and full engine power seems to be lost, inspect the air line to the cover and the cover gasket for air leaks. If no air leaks are apparent, inspect the diaphragm. A damaged diaphragm will not allow the fuel rack to open completely, acceleration will be sluggish and full engine power cannot be obtained.