Usage:
The timing gears are located in a compartment at the rear of the cylinder block which uses the front face of the flywheel housing as a cover. The timing gears keep the rotation of the crankshaft, camshaft, balancers if so equipped, and the governor drive gear in the correct relationship to each other. A gear in front of the crankshaft rear flange drives the timing gears.
TIMING GEARS (8 Cylinder Engines Illustrated)
1. Governor drive gear. 2. Camshaft cluster gear. 3. Balancer gear. 4. Crankshaft gear.
The crankshaft gear (4) drives the camshaft cluster gear (2) which in turn drives the balancer gear (3) and governor drive gear (1). The camshaft small cluster gear is held to the camshaft with key, plate and bolts.
NOTE: The 8 cylinder engines use balancers, therefore balancer gear (3) is used only on these engines.
Camshaft
The camshaft rotates in bearings located in the V of the engine. It is driven by a gear on the rear of the crankshaft. The camshaft is positioned by a thrust washer secured to the face of the cylinder block. The cams which actuate the inlet and exhaust valves are forged as one piece with the camshaft.
Camshaft Cluster Gear Removal
Position the engine with No.1 piston at top center on the compression stroke as follows:
1. Remove the timing mark cover on the flywheel housing and turn the flywheel in the direction of engine rotation until No.1 piston is at TC (top center) on compression stroke as indicated by flywheel pointer (1) and the position of No.1 cylinder valves.
TIMING MARKS ON FLYWHEEL (16 Cylinder Engine Illustrated)
TIMING MARKS ON FLYWHEEL (12 and 8 Cylinder Engines Illustrated)
1. Pointer.
NOTE: If the flywheel is turned too far, turn it back about 60° and again rotate the flywheel in the direction of normal rotation until No.1 piston is at TC (top center) on compression stroke as indicated by the flywheel pointer.
NOTE: On earlier natural gas engines with magnetos on the engine see the topic, TIMING THE MAGNETO.
2. Remove the flywheel housing. See the covering topic.
PREPARING TO REMOVE CAMSHAFT CLUSTER GEAR
1. Bolt and lock. 2. Small cluster gear. 3. Bolts (eight). 4. Retainer. 5. Large cluster gear.
3. Remove the large cluster gear (5) as shown.
| NOTICE |
|---|
To avoid piston and valve interference, do not rotate the crankshaft with the large camshaft cluster gear removed and the camshaft installed. |
LARGE CLUSTER GEAR REMOVAL
5. Large cluster gear.
4. Remove the bolts and locks (1), which secure the thrust washer to the cylinder block, through the holes in the small cluster gear and remove the thrust washer.
5. Remove the service meter drive adapter at front of the camshaft on later engines.
6. Remove the small cluster gear by using 7F9540 Hydraulic Puller, 8F3672 Puller Plate, 8B7548 Push Puller with 8B7550 Legs, two 4B4280 Washers (1/2 in.) and two L1329 Bolts, 1/2"-13NC, 3 in. (76,2 mm) long.
TOOLS NEEDED FOR PULLING CAMSHAFT GEAR
7. Inspect all parts for wear or damage and replace if necessary. See the SPECIFICATIONS, for the correct clearances and dimensions.
Camshaft Cluster Gear Installation
1. Install the small cluster gear (2), the thrust washer and the retainer (3), tightening the bolts which secure the retainer to torque of 60 to 70 lb. ft. (8,3 to 9,7 mkg).
NOTE: Make certain the engine is positioned with the No.1 piston at top center on the compression stroke.
2. Mark the cluster gear C-mark and the crankshaft gear punch marked tooth with chalk, to help align the teeth. The back of the gears can be marked for checking with mirror after installation.
3. Install the large cluster gear (1), align the C-mark on the cluster gear with the punch marked tooth on the crankshaft gear. Do this by looking through the hole (7) in the crankshaft flange.
INSTALLING CLUSTER GEAR
1. Large cluster gear. 2. Small cluster gear. 3. Retainer. 4. A-marks. 5. Dowel. 6. Alignment mark for flywheel installation. 7. Hole in crankshaft flange.
4. On 8 cylinder engines, tilt the large cluster gear and rotate the balancer gear until the A-marks (4) line up.
5. With the timing marks aligned, slide the large cluster gear over the dowel (5) in the small cluster gear and install the mounting bolts.
CHECKING ALIGNMENT WITH MIRROR AND CHALK ON BACK OF GEARS
Camshaft Removal and Installation
1. Remove the fuel pump and governor drive housing, or, on natural gas engines, the governor drive housing. See the covering topics.
2. Remove the flywheel housing, vibration damper housing if so equipped. The Service Meter and drive assembly should be removed on later engines. See the covering topics.
3. Remove the large cluster gear from the camshaft. See the topic, CAMSHAFT CLUSTER GEAR REMOVAL.
PREPARING TO REMOVE CAMSHAFT
1. Push rods. 2. Thrust washer. 3. Bolt and lock.
4. Remove the push rods (1). See the topic, VALVE ROCKER ARM REMOVAL AND INSTALLATION.
5. Hold the valve lifters off the cam lobes as described in the topic, VALVE LIFTER REMOVAL.
6. Remove the bolts and locks (3) that hold the thrust washer (2) to the cylinder block and remove the thrust washer.
PREPARING TO REMOVE CAMSHAFT
4. FT751 Pilot.
7. Install the FT751 Pilot (4) on the front of the camshaft, then remove the camshaft:
Camshaft approximate weights:
16 Cylinder Engine ... 100 lbs.(45,4 kg)
12 Cylinder Engine ... 85 lbs.(38,6 kg)
8 Cylinder Engine ... 60 lbs.(27,2 kg)
NOTE: One end of the camshaft is stamped with an F-mark for assisting in correct installation of the cluster gear. On SAE standard rotation engines, (Counterclockwise as viewed from the flywheel end) install the cluster gear on the end opposite the F-mark. On SAE opposite rotation engines (clockwise as viewed from the flywheel end) install this gear on the end with the F-mark.
CAMSHAFT INSTALLATION
4. FT751 Pilot.
8. Inspect the camshaft and camshaft bearings for wear or damage and replace if necessary. See SPECIFICATIONS, for the correct clearances and tolerances.
NOTE: If the camshaft bearings are to be replaced, it will be necessary to remove the valve lifters.
OIL HOLE IN BEARING
5. Oil hole.
9. Align the oil hole (5) in the bearing with the oil passages in the block if the bearings are replaced.
10. Install the camshaft and camshaft cluster gear. See the topic, CAMSHAFT CLUSTER GEAR INSTALLATION, for information on timing the cluster gear.