0320284 JOHNSON LINK, Spark advance

Illustration 1 g00514897
3608 Cylinder and valve location (A) Inlet valves (B) Exhaust valves
Table 1
Crankshaft Positions For Fuel Injector Timing And Valve Lash Setting    
3608
Engine     Check And Adjust With No. 1 Piston On The Following Stroke: (1)    
Top Center Compression Stroke Top Center Exhaust Stroke    
SAE Standard Rotation Engines (2)    
Inlet
Valves     1-4-6-7     2-3-5-8    
Exhaust Valves     1-2-4-6     3-5-7-8    
Fuel
Injectors     2-3-5-8     1-4-6-7    
Firing
Order     1-6-2-5-8-3-7-4    
SAE Opposite Rotation Engines (3)    
Inlet
Valves     1-2-4-6     3-5-7-8    
Exhaust Valves     1-4-6-7     2-3-5-8    
Fuel
Injectors     3-5-7-8     1-2-4-6    
Firing
Order     1-4-7-3-8-5-2-6    
( 1 ) Put the No. 1 piston at the top center position and identify the correct stroke. Refer to Testing and Adjusting, "Fuel System". After the top center position for a particular stroke is found and the adjustments are made for the correct cylinders, remove the timing pin. Turn the flywheel for 360 degrees in the direction of normal engine rotation. The rotation will put the No. 1 piston at the top center position on the other stroke. Install the timing pin in the crankshaft and complete the adjustments for the cylinders that remain.
( 2 ) SAE Standard Rotation Engines turn in the counterclockwise direction when the engines are viewed from the flywheel end.
( 3 ) SAE Opposite Rotation Engines turn in the clockwise direction when the engines are viewed from the flywheel end.Valve Lash
Valve lash is measured between the rocker arm and the bridge for the valves. All of the valve lash measurements and valve lash adjustments must be made with the engine stopped. Make sure that the valves are fully closed.Valve Lash Check
A valve lash adjustment is not necessary if the measurement of the valve lash is in the acceptable range. The acceptable range is given in Table 2. Caterpillar Inc. recommends adjustment of the valve lash after the following intervals:
The first 1000 hours of operation
2000 hours of operation
Every 2000 hours of operation
Table 2
Valve Lash Check (1)    
Valves     Acceptable Range    
Inlet    
0.52 to 0.68 mm (0.020 to 0.027 inch)    
Exhaust    
0.92 to 1.08 mm (0.036 to 0.042 inch)    
( 1 ) The valve lash check should only be done while the engine is stopped.Use the procedure that follows in order to check valve lash:
Rotate the No. 1 piston to the Top Center position. Refer to Testing and Adjusting, "Fuel System". With the No. 1 piston at the Top Center position of the compression stroke, check the valves. Refer to Table 1.
Adjust the valve bridges. Refer to "Bridge Adjustment".
Insert the 6V-3075 Dial Indicator from the timing group into the 4C-6593 Adjustment Tool. Tighten the retaining screw finger tight.Note: Make sure that the 6V-3075 Dial Indicator is used with the short contact point.
Install the adjustment tool on the rocker base the in threaded hole that is nearest to the end of the rocker arm to be adjusted. Position the dial indicator stem over the flat area on the end of the rocker arm. Tighten the knob. Rotate the dial indicator so that the dial indicator can be easily read. Make sure that the adjustment tool is rigid and that the dial indicator stem moves freely.
Lift firmly on the end of the rocker arm that has the adjusting screw and set the dial indicator to zero.
Lift firmly on the valve end of the rocker arm and read the dial indicator.
Try to move the rocker arm while you are lifting on the rocker arm. The dial indicator reading will vary. Read the dial indicator when the rocker arm is positioned in the groove of normal operation. Refer to Table 2 for the specifications regarding valve lash. If the dial indicator reading is within specifications, move to the next valve.
If the dial indicator reading is not within specifications, reset the valve lash. After the adjustment is complete proceed to the next valve. Refer to "Valve Lash Adjustment".
After completing all of the valve lash checks and the valve lash adjustments for this crankshaft position, remove the timing pin from the crankshaft. Rotate the crankshaft to the next position. Install the timing pin in the crankshaft. Repeat Steps 2 through 8.
Remove the timing pin from the crankshaft when all valve lash adjustments have been completed.Valve Lash Adjustment
The procedures for engine valve lash should be performed according to the information in the Service Manual.Operation of Caterpillar engines with improper valve adjustments will reduce engine efficiency. This reduced efficiency could result in excessive fuel usage and/or shortened engine component life.
Note: The first interval that is recommended for the valve lash setting for a new engine or a rebuilt engine is 1000 hours.