5031289 JOHNSON PLUG, OIL VENTURI

Illustration 1 g02783979
(1) Valve Lash Measurement
Table 1
Valve Lash Setting
Inlet Valve 0.145 mm (0.00571 inch) to 0.185 mm (0.00728 inch)
Exhaust Valve 0.145 mm (0.00571 inch) to 0.185 mm (0.00728 inch) Valve Lash Adjustment
If the valve lash requires adjustment several times in a short time, excessive wear exists in a different part of the engine. Repair the problem in order to prevent more damage to the engine.Not enough valve lash can be the cause of rapid wear of the camshaft and valve lifters. Not enough valve lash can indicate that the seats for the valves are worn.Valves become worn due to the following causes:
Incorrect operation of fuel injection nozzles
Excessive dirt and oil are present on the filters for the inlet air.
Incorrect fuel settings on the fuel injection pump.
The load capacity of the engine is frequently exceeded.Too much valve lash can cause broken valve stems, springs, and spring retainers. Too much valve lash can be an indication of the following problems:
Worn camshaft and valve lifters
Worn rocker arms
Bent pushrods
Broken socket on the upper end of a pushrod
Loose adjustment screw for the valve lashIf the camshaft and valve lifters show rapid wear, look for fuel in the lubrication oil or dirty lubrication oil as a possible cause.The valve lash is measured between the top of the valve stem and the rocker arm lever.Note: No. 1 cylinder is at the front of the engine.Remove the valve mechanism cover and perform the following procedures in order to adjust the valve lash:Note: When these procedures are performed, the front housing must be installed.
Illustration 2 g02783977
(2) Feeler Gauge
(3) Adjustment Screw
Accidental engine starting can cause injury or death to personnel.To prevent accidental engine starting, turn the ignition switch to the OFF position, place a do not operate tag at the ignition switch location and disconnect and tape the electrical connection to the stop solenoid that is located on the fuel injection pump.
Find top dead center for No. 1 piston.
Illustration 3 g03384598
Align the "1TC" mark (5) on the flywheel with the mark (4) on the flywheel housing.
Turn the flywheel .26 radians (15° ) to determine if the piston is at the compression top dead center or in the overlap position. The flywheel has a mark 1TC and 4 lines that represent increments of .09 radians (5° ) of the crank angle from .17 radians (10° ) to .44 radians (25° ) before 1 TC.The piston is at the compression top dead center when both the inlet and the exhaust valves do not move.The piston is at the overlap position when both the valves move.
Refer to Table 2 to adjust valve clearance. Examine the subsequent valve clearance (1) at the mark "x" with a feeler gauge (2).
Table 2
Adjustable Cylinder Location of Piston Valve Arrangement
Intake Exhaust
When No. 1 piston is at compression top dead center No. 1 X X
No. 2 X
No. 3 X
No. 1 piston at overlap No.1
No.2 X
No.3 X
After each adjustment, tighten the valve adjustment screw locknut while adjustment screw (3) is being held from turning.
Turn the flywheel 6.28 radians (360° ) and align the "1TC" mark on the flywheel housing. Adjust the remaining valves per Table 2.
Turn the flywheel counterclockwise two or three times and examine the valve clearances again.