Conversion of Ignition Systems for G379 Engines{1550, 1552} Caterpillar

Engine:

G379 (S/N: 72B1-UP)

Introduction

This Special Instruction describes the installation of the following conversion arrangements for G379 Engines:

• The 231-6567 Ignition Conversion Arrangement (Standard)

• The 231-6570 Ignition Conversion Arrangement (Shielded)

Note: The 231-6570 Ignition Conversion Arrangement (Shielded) meets requirements of the Canadian Standards Accociation (CSA) for hazardous environments.

Both of the conversion arrangements include the 2W-3741 Magneto .

Originally, the G379A Engines used the 7W-1477 Magneto . The original magneto is no longer available.

The coils of the ignition transformers for the original magneto are not compatible with the 2W-3741 Magneto . For this reason, the conversion arrangements also include new ignition transformers and wiring.

Do not perform any procedure in this Special Instruction until you read this information and you understand this information.

Installation of the 231-6567 Ignition Conversion Arrangement (Standard)

Required Parts

Table 1

231-6567 Ignition Conversion Arrangement (Standard)
Part	Qty
2H-2143 Wire Marker	1
2L-8066 Ring Terminal	8
2L-8068 Ring Terminal	1
2L-8076 Ring Terminal	8
2L-8078 Ring Terminal	3
2W-3741 Magneto	1
2W-3742 Wiring Harness	1
2W-3747 Transformer	8
5M-2894 Hard Washer	2
5P-1476 Spade Terminal	1
6A-3361 Electrical Wire	8 m (26.25 ft)
7W-8666 Plug Wire Assembly	8
8L-8413 Cable Strap	20

Remove the Original Parts (Standard Ignition)

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Illustration 1	g00948835
(1) Wire assembly (2) Transformer (3) Wiring harness (4) Magneto (5) Conduit (6) Ground strap

1. Remove wire assembly (1) .

2. Remove transformer (2) .

   Keep the transformer's mounting bolts and washers. The fasteners will be reused.

3. Disconnect wiring harness (3) from the instrument panel (not shown) and from magneto (4). Loosen the mounting clips for the wiring harness.

   The clips will be reused.

4. Cut the cable straps from the wiring harness. Pull the wiring away from the engine through conduit (5) and remove the wiring harness.

   The conduit will be reused.

5. Disconnect ground strap (6) from magneto (4) .

   Do not remove the ground strap from the engine. The ground strap will be reused.

6. Remove magneto (4) .

   Keep the magneto's mounting bolts. The bolts will be reused.

Install the New Parts (Standard Ignition)

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Illustration 2	g00948836
(1) 2W-3747 Transformer (2) 7W-8666 Plug Wire Assembly (3) 2W-3742 Wiring Harness (4) Original conduit (N) Ground wire (G) Ignition shutoff's wire

1. Use the original mounting bolts and washers to install transformers (1) .

2. Connect wire assemblies (2) to the transformers and to the spark plugs.

3. Install wiring harness (3) .

   1. Compare each wire on the wiring harness to each terminal on the harness connector. Refer to ""Wiring Diagrams for the 231-6567 Ignition Conversion Arrangement (Standard) " ". Use the 2H-2143 Wire Marker to identify each wire for each cylinder's transformer.

   2. Route the wiring harness through original conduit (4) toward the appropriate transformers.
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   Illustration 3	g00949729
   Typical magnetic switch (M1) Switch's terminal for the wire from the magneto's terminal "G"

   3. Route the wire from terminal "G" to the instrument panel. Crimp the 5P-1476 Spade Terminal to the wire. Connect this terminal to terminal "M1" on the magnetic switch in the instrument panel.

   4. Route the wire from terminal "N" to a mounting bolt for the transformer of cylinder number 1.

   5. Crimp a 2L-8076 Ring Terminal to the wires for these terminals: "A", "B", "C", "D", "E", "F", "H" and "I". Connect these terminals to the positive "+" post on the appropriate transformer. Route the wires over the bent portion of the mounting brackets for the transformers. Make sure that the wiring does not contact the mounting brackets.

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Illustration 4	g00949758
Schematic for the ground wiring (5) 2L-8066 Ring Terminal (eight places) (6) 2L-8078 Ring Terminal (three places) (7) 2L-8068 Ring Terminal (one place)

4. Use the 6A-3361 Electrical Wire and the appropriate ring terminals to fabricate the ground wiring for the transformers. Assemble the ground wiring according to Illustration 4.

5. Tie the wiring into straight bundles with a 8L-8413 Cable Strap at every 7.5 to 10 cm (3 to 4 inches).

6. Use the original clips to secure the wires under the air inlet manifolds.

7. Perform the ""Magneto Installation and Timing" " procedure.

Wiring Diagrams for the 231-6567 Ignition Conversion Arrangement (Standard)

Note: The front end of the engine is opposite the flywheel end. The left and right sides of the engine are determined by the flywheel end. The number 1 cylinder is the right front cylinder. Refer to Illustration 5 for the locations of the cylinders.

Illustration 5	g00949061
Cylinders' locations

The wiring from the magneto's connector to the ignition transformers is determined by the direction of the engine crankshaft's rotation. The direction of rotation is determined from viewing the flywheel end.

Illustration 6 is a wiring diagram for engines with standard rotation: when the engine is viewed from the flywheel end, the crankshaft rotates in the counterclockwise direction.

Illustration 7 is a wiring diagram for engines with opposite rotation: when the engine is viewed from the flywheel end, the crankshaft rotates in the clockwise direction.

Standard Counterclockwise Rotation

Table 2

Engine Firing Sequence and Corresponding Magneto's Terminals for G379 Engines Standard Counterclockwise Rotation
Firing Sequence	1	8	5	4	7	2	3	6
Magneto's Terminals	A	B	C	D	E	F	H	I

Illustration 6	g00949069
Wiring diagram for standard counterclockwise rotation

Clockwise Rotation

Table 3

Engine Firing Sequence and Corresponding Magneto's Terminals for G379 Engines Clockwise Rotation
Firing Order	1	4	5	2	7	6	3	8
Magneto's Terminals	B	C	D	E	F	H	I	A

Illustration 7	g00949070
Wiring diagram for clockwise rotation

Installation of the 231-6570 Ignition Conversion Arrangement (Shielded)

Required Parts

Table 4

231-6570 Ignition Conversion Arrangement (Shielded)
Part	Qty	Part	Qty
0S-1571 Bolt	4	4W-5468 Harness	1
0S-1588 Bolt	2	4W-5470 Junction Box As	1
0S-1594 Bolt	2	4W-6090 Bracket	1
1H-5167 Wire Clip	3	4W-6091 Conduit	1
1L-6023 Terminal Strip	3	4W-6733 Plate	1
1N-3735 Harness	1	4W-6742 Harness	2
1N-3736 Harness	1	5F-7207 Spacer	2
1N-3739 Harness	1	5J-0299 Clip	4
1N-3740 Harness	1	5M-2894 Hard Washer	16
1N-3741 Harness	1	5P-1475 Spade Terminal	2
1S-0996 Clip	2	5P-1476 Spade Terminal	28
1S-9593 Cable Strap	16	5P-4508 Electrical Wire	1
2M-0849 Hard Washer	2	6V-7383 Clip	3
2W-3741 Magneto	1	6V-8801 Nut	6
3B-4501 Lockwasher	21	8C-8514 Screw	1
3H-3627 Screw	12	8L-8413 Cable Strap	30
3J-5389 Plug	10	9L-3560 Elbow	1
3K-8667 Jumper	10	9S-1366 Bolt	2
3M-7045 Plug	2	9Y-3985 Spark Plug	8
3S-2093 Cable Strap	3	9Y-3987 Spark Plug Cover	8
4B-4278 Washer	2	000-7244 Pipe Elbow	1
4L-2791 Markers	1	107-2400 Transformer	8
4W-5467 Harness	1	-

Remove the Original Parts (Shielded Ignition)

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Illustration 8	g00948821
Top view (1) Conduit (2) Body (3) Clip

1. Remove conduit (1), body (2), and the associated wiring. Keep one of the body's mounting bolts, nuts, lockwashers, and washers.

   The fasteners will be reused.

2. Keep original clip (3) in place.

   The clip will be reused.

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Illustration 9	g00948822
(4) Transformer (5) Spark plug (6) Conduit (7) Ground strap (8) Magneto

3. Remove each transformer (4) and spark plug (5) .

4. Remove conduit (6) and the associated wiring.

5. Disconnect ground strap (7) from magneto (8) .

   Do not remove the ground strap from the engine. The ground strap will be used with the new magneto.

6. Remove magneto (8) .

   Keep the magneto's mounting bolts. The bolts will be reused.

Install the New Parts (Shielded Ignition)

Assemble the Junction Box

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Illustration 10	g00951099
(1) 4W-5470 Junction Box As (2) 1L-6023 Terminal Strip (3) 3H-3627 Screw (4) 3B-4501 Lockwasher (5) 8C-8514 Screw (6) 5P-1475 Spade Terminal (7) 5P-4508 Electrical Wire (8) 3K-8667 Jumper (9) 3M-7045 Plug (10) 3J-5389 Plug (11) 000-7244 Pipe Elbow (12) 9L-3560 Elbow

1. Orient the junction box according to Illustration 10: upon installation, the side with the two 3/4-14 holes for plugs (9) is in the upward position.

2. Install terminal strips (2) into junction box (1) .

   1. For each of the two outer terminal strips, use four screws (3). Place one lockwasher (4) under each screw head. Refer to view "A-A" in Illustration 10.

   2. For the middle terminal strip, use four screws (3) and twelve lockwashers (4). For each screw, place two lockwashers between the terminal strip and the junction box. Place one lockwasher under each screw head. Refer to view "B-B" in Illustration 10.

3. Install ground screw (5) and one lockwasher (4) .

4. Use two spade terminals (6) and wire (7) to fabricate a jumper wire. Install the jumper wire between ground screw (5) and the right terminal strip's upper left terminal.

5. Install ten jumpers (8) in order to provide a ground path for the right terminal strip's right terminals. Refer to view "C-C" in Illustration 10. Also refer to ""Wiring Diagrams for the 231-6570 Ignition Conversion Arrangement (Shielded) " ".

6. Label the appropriate terminals for identification. Refer to ""Wiring Diagrams for the 231-6570 Ignition Conversion Arrangement (Shielded) " ".

   The 4L-2791 Markers can be used to label the terminals for the cylinder numbers. Otherwise, use a permanent marker.

7. Install two plugs (9) in the top of the junction box.

8. Install ten plugs (10) according to the locations in Illustration 10.

9. Install elbow (11) (45 degree) for the magneto's harness.

10. Install elbow (12) (90 degree) for the wiring to the customer's shutoff switch.

Install the Junction Box

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Illustration 11	g00951389
Front view and right side view (1) 4W-6090 Bracket (2) 0S-1594 Bolt (3) 4B-4278 Washer (4) 5M-2894 Hard Washer (5) 4W-6733 Plate (6) 0S-1588 Bolt (7) 6V-8801 Nut (8) 9S-1366 Bolt (9) 2M-0849 Hard Washer (10) 5F-7207 Spacer (11) 0S-1571 Bolt

1. Install bracket (1) onto the flange of the exhaust manifold for cylinder number 1. Use two bolts (2), two washers (3), and two hard washers (4) .

2. Attach mounting plate (5) to bracket (1) with two bolts (6), four hard washers (4), and two nuts (7) .

3. Use two bolts (8), two hard washers (9), and two spacers (10) to attach the mounting plate to the flanges on the inlet manifolds for cylinder numbers 1 and 3. Place the spacers between the mounting plate and the flanges.

4. Attach the junction box to the mounting plate with four bolts (11), four nuts (7), and eight hard washers (4) .

Install the Ignition System's Components

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Illustration 12	g00948839
Section view of the spark plug and bottom view of electrode gaps for two ground electrodes

1. Set the spark plug's electrode gap.

   Electrode gap ... 0.37 ± 0.004 mm (0.0146 ± 0.0002 inch)

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Illustration 13	g00952470
(1) 9Y-3985 Spark Plug (2) 107-2400 Transformer (3) 9Y-3987 Spark Plug Cover

2. Install spark plug (1) .

   Torque ... 38 ± 3 N·m (28 ± 2 lb ft)

3. Install transformer (2). Thread the transformer onto the spark plug until the transformer is finger tight. Then tighten the transformer for an additional 1/8 of a turn (45 degrees).

4. Slide cover (3) onto the transformer. Make sure that the cover fits snugly over the spark plug adapter.

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Illustration 14	g00953018
Right side ignition harnesses (4) 1N-3735 Harness (5) 4W-5467 Harness (6) 4W-6742 Harness (7) 4W-6742 Harness (8) 6V-7383 Clip (9) 1H-5167 Wire Clip

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Illustration 15	g00948830
Left side ignition harnesses (8) 6V-7383 Clip (9) 1H-5167 Wire Clip (10) 1N-3736 Harness (11) 1N-3739 Harness (12) 1N-3740 Harness (13) 1N-3741 Harness

5. Install the ignition harnesses.

   1. Connect each harness to the transformer for the appropriate cylinder. Refer to Table 5.
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      Table 5

      Cylinder Number and Corresponding Ignition Harness
      Cylinder	Part
      1	4W-6742 Harness
      2	1N-3736 Harness
      3	4W-6742 Harness
      4	1N-3739 Harness
      5	4W-5467 Harness
      6	1N-3740 Harness
      7	1N-3735 Harness
      8	1N-3741 Harness

   2. Crimp one 5P-1476 Spade Terminal onto each harness wire.

   3. Use the 4L-2791 Markers in order to label the harness wires' terminals. Label all of the harness wires with the appropriate numbered markers.

      For example, attach two "1" markers on the two wires from the harness for cylinder number 1.

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   Illustration 16	g00953173
   Locations for the ignition harnesses on the sides of the junction box

   4. Route each harness to the appropriate hole in the side of the junction box. Refer to Illustration 16. Make sure that the harnesses do not contact sharp edges. Make sure that the harnesses do not have acute bends. Screw the fittings into the holes.

   5. Connect the harness wiring to the appropriate terminals in the junction box. Refer to ""Wiring Diagrams for the 231-6570 Ignition Conversion Arrangement (Shielded) " ".

   6. Bolt clips (8) to the air inlet manifolds' flanges in order to secure a harness on each side of the engine. Use one clip on the right side and two clips on the left side.

   7. Tie the harnesses into bundles with clips (9). Use one clip on the right side and two clips on the left side.

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Illustration 17	g00948828
Front view (14) 4W-6091 Conduit (15) 1S-0996 Clip (16) 5J-0299 Clip (17) Original clip (18) 4W-5468 Harness

6. Connect flexible conduit (14) to the 90 degree fitting on the bottom of the junction box. Route the conduit to the customer's shutoff switch.

   1. If the customer's shutoff switch is on the left side of the engine, route the conduit around the front of the engine. Secure the conduit by bolting clip (15) to the location of the body that was removed for Step 1 of the ""Remove the Original Parts (Shielded Ignition)" " procedure. Install the clip with one of the body's original mounting bolts, nuts, lockwashers, and washers.

   2. Also, secure the conduit with original clip (17) that was retained for Step 2 of the ""Remove the Original Parts (Shielded Ignition)" " procedure.

7. Connect flexible conduit (14) to the box for the customer's shutoff switch. Route the customer's wiring from the shutoff switch through the conduit. Attach two 5P-1476 Spade Terminals to the wiring and connect the wiring to the appropriate terminals in the junction box. Refer to ""Wiring Diagrams for the 231-6570 Ignition Conversion Arrangement (Shielded) " ".

8. Use three clips (16) to secure the ignition harnesses from the left side of the engine to the flexible conduit.

9. Connect magneto's harness (18) to the 45 degree fitting on the bottom of the junction box. Route the other end of the harness toward the magneto drive. Use clip (16) to tie the magneto's harness and the ignition harnesses from the right side of the engine into a bundle.

10. Crimp one 5P-1476 Spade Terminal onto each wire of magneto's harness (18) .

Note: The magneto's harness wires are marked with letters that correspond to the terminals on the magneto.

11. Connect the magneto's harness wiring to the appropriate terminals in the junction box. Refer to ""Wiring Diagrams for the 231-6570 Ignition Conversion Arrangement (Shielded) " ".

12. Use these supplied cable straps to secure any loose harness and/or wiring: 1S-9593 Cable Straps , 3S-2093 Cable Straps and 8L-8413 Cable Straps .

13. Perform the ""Magneto Installation and Timing" " procedure.

Wiring Diagrams for the 231-6570 Ignition Conversion Arrangement (Shielded)

The front end of the engine is opposite the flywheel end. The left and right sides of the engine are determined by the flywheel end. The number 1 cylinder is the right front cylinder. Refer to Illustration 18 for the cylinders' locations.

Illustration 18	g00949061
Cylinders' locations

The wiring from the magneto's connector to the junction box is determined by the direction of the engine crankshaft's rotation. The direction of rotation is determined from viewing the flywheel end.

Illustration 19 is a wiring diagram for engines with standard rotation: when the engine is viewed from the flywheel end, the crankshaft rotates in the counterclockwise direction.

Illustration 20 is a wiring diagram for engines with opposite rotation: when the engine is viewed from the flywheel end, the crankshaft rotates in the clockwise direction.

Standard Counterclockwise Rotation

Table 6

Engine Firing Sequence and Corresponding Magneto's Terminals for G379 Engines Standard Counterclockwise Rotation
Firing Order	1	8	5	4	7	2	3	6
Magneto's Terminals	A	B	C	D	E	F	H	I

Illustration 19	g00949106
Wiring diagram for standard counterclockwise rotation

Clockwise Rotation

Table 7

Engine Firing Sequence and Corresponding Magneto's Terminals for G379 Engines Clockwise Rotation
Firing Order	1	4	5	2	7	6	3	8
Magneto's Terminals	B	C	D	E	F	H	I	A

Illustration 20	g00949107
Wiring diagram for clockwise rotation

Magneto Installation and Timing

1. Remove the cover from the flywheel housing in order to observe the timing marks on the flywheel.

2. Refer to Table 8 in order to determine the initial ignition timing.
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   Table 8

   Recommendations for Initial Ignition Timing
   Compression Ratio	Aspiration	Aftercooler's Rating	Fuel	Degrees Before Top Center
   10:1	Natural aspiration	-	Dry, processed natural gas	30
   10:1	Turbocharged aftercooled	32 °C (90 °F)		20
   10:1	Natural aspiration	-	Propane	12.5
   7:1			Dry, processed natural gas	30
   7:1	Turbocharged aftercooled	54 °C (130 °F)
   7:1	Natural aspiration	-	Raw field gas	20
   			Butane
   7:1	Turbocharged aftercooled	-	Propane
   			Scrubbed field gas

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Illustration 21	g00735090
Flywheel timing marks

3. Turn the crankshaft in the direction of engine rotation until the number 1 piston is coming up on the compression stroke. Place that piston in the position that was determined from Table 8. Observe the timing marks on the flywheel and turn the crankshaft until the desired timing mark on the flywheel is directly under the pointer for the timing marks on the flywheel.

   Refer to Testing and Adjusting, "Finding Top Center Position for No. 1 Piston". Also observe the direction that the pointer on the magneto moves.

Note: The magneto has two marks that indicate the rotation of the magneto ("CW" and "CCW"). The magneto also has a pointer that moves clockwise or counterclockwise when the magneto's coupling is rotated. When you time the magneto to the engine, the pointer must indicate the correct timing mark.

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Illustration 22	g00743172
Marks for the direction of rotation and pointer on the magneto

4. Rotate the magneto's coupling and observe the pointer on the magneto. Align the pointer on the magneto with the appropriate mark for the direction of rotation.

   For engines with standard counterclockwise rotation, align the pointer with the "CCW" mark.

   For engines with clockwise rotation, align the pointer with the "CW" mark.

   When the desired timing mark on the flywheel is obtained, the pointer on the magneto must be aligned with the appropriate mark.

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Illustration 23	g00950358
(1) Lugs on the magneto's coupling (2) Magneto drive's shaft (3) Original mounting bolt (4) 5M-2894 Hard Washer (3) Magneto's harness

5. Verify that lugs (1) on the magneto's coupling are approximately at the 12 o'clock and 6 o'clock positions. Observe the corresponding positions of the slots in the magneto drive's shaft (2). If the slots do not align with the lugs, pull the shaft away from the magneto drive in order to rotate the shaft to the correct orientation. Push the shaft back into the magneto drive.

6. Keep the pointer on the magneto aligned with the appropriate mark and install the magneto. Use the original mounting bolts (3) with the new hard washers (4) .

7. Connect wiring harness (5) to the magneto.

8. Attach a timing light to the lead for the spark plug of the number 1 cylinder.

9. Start the engine. Operate the engine at high idle speed.

Note: Do not adjust the timing at low idle because of the timing advance in the magneto.

10. Use the timing light to observe the timing marks on the flywheel. If necessary, slightly loosen the magneto's mounting bolts and rotate the magneto in order to gain the desired timing. When the timing is correct, tighten the magneto's mounting bolts.

11. Apply a load to the engine. Ramp the load and operate the engine at the rated load.

Note: Detonation produces a pinging noise and/or a sharp metallic knocking.

12. Adjust the timing in order to provide a six degree margin for detonation.

    1. Slightly loosen the magneto's mounting bolts and rotate the magneto in order to advance the timing.

    2. Slowly advance the timing until mild detonation occurs.

    3. Then, slowly rotate the magneto in order to retard the timing by six degrees. Tighten the mounting bolts for the magneto.

13. Stop the engine.

14. Remove the timing light.

15. Install the cover for the flywheel housing.