0391254 JOHNSON BASE, Air silencer

Required Tools
The following tool is required to perform this procedure:
Table 1
Tools Needed
Part Number Part Name Quantity
8H-8581 Feeler Gauge 1 Valve Lash Check
Measure the valve lash between the rocker arm and the valve bridge. Perform checks and adjustments with the engine stopped. Ensure that the valves are seated.An adjustment is not necessary if the measurement of the valve lash is in the acceptable range. Adjust the valve lash while the engine is stopped. The range is specified in Table 2.
Table 2
CG137 Engines
Engine Crankshaft Position Inlet Valves Exhaust Valves
CG137-8 Valve Lash Check (Stopped Engine) 0.38 0.10 mm (0.015 0.004 inch) 1.02 0.10 mm (0.040 0.004 inch)
CG137-8 TC Compression Stroke(1) 1-2-5-7 1-3-4-8
TC Exhaust Stroke(2) 3-4-6-8 2-5-6-7
Firing Order 1-8-4-3-6-5-7-2(3)
(1) Engine pinned at the position for No. 1 cylinder
(2) Engine pinned at 360° from the TC compression stroke
(3) The No. 1 cylinder is at the front left side of the engine.If the measurement is not within this range, adjustment is necessary.Valve Bridge Adjustment
When the head is disassembled, mark the valve bridges for the respective cylinders. Adjustment of the bridge will be necessary after grinding the valves or other reconditioning of the cylinder head.The valve bridge must be adjusted before the valve lash is adjusted. The valve bridge can be adjusted without removing the rocker arms and shafts.
Illustration 1 g02624596
Location of the valve components for valve bridge adjustment (left front side engine view)
(1) Ignition transformer
(2) Rocker arm
(3) Valve bridge
(4) Adjusting screw
(5) Locknut
(6) Bridge dowelUse the following procedure to adjust the valve bridges:
Remove the valve cover.
Ensure that the No. 1 piston is at the top center (TC) position. Refer to Testing and Adjusting, "Finding the Top Center Position for No. 1 Piston".
Work on the appropriate cylinders that are listed in Table 2.
Disconnect ignition transformer (1) from the ignition harness at the connector.
Remove the transformer from the cylinder head.Note: If the cylinder head is disassembled, keep the valve bridges with the respective valves. Check that bridge dowel (6) is installed to the correct height. Lubricate the bridge dowel, the bore for the bridge dowel, and the top contact surface of the valve bridge. Install the valve bridge on the dowel.
Loosen locknut (5) and adjusting screw (4).
Press straight down on rocker arm (2) at the contact point for valve bridge (3). Turn the adjusting screw clockwise until the screw just contacts the valve stem.
Turn the adjusting screw clockwise for an additional 25 5 degrees. The additional turn will straighten the valve bridge onto the dowel and compensate for slack in the threads of the adjustment screw.
Hold the adjusting screw in position and the tighten locknut to 30 4 N m (22 3 lb ft).
Ensure that the valve lash is correct. Refer to "Valve Lash Check". If necessary, set the valve lash to the correct tolerance. Refer to "Valve Lash Adjustment".
Install the transformer into the cylinder head.
Connect the ignition harness.
Install the valve cover.Valve Lash Adjustment
The valve bridge must be adjusted before the valve lash is adjusted.
Illustration 2 g02625361
Location of the valve components for valve bridge adjustment (left front side engine view)
(1) Ignition transformer
(2) Adjusting screw
(3) Locknut
(4) Rocker arm
(5) Valve bridge
Ensure that the No. 1 piston is at the top center (TC) position. Refer to Testing and Adjusting, "Finding the Top Center Position for No. 1 Piston".
Work on the appropriate cylinders that are listed in Table 2.
Disconnect ignition transformer (1) from the ignition harness at the connector.
Remove the transformer from the cylinder head.
Loosen locknut (3) and adjusting screw (2).
Insert the appropriate feeler gauge between rocker arm (4) and the wear seat of valve bridge (5). Refer to Table 3.
Table 3
Valve Lash Setting: Engine Stopped
Inlet 0.38 0.10 mm (0.015 0.004 inch)
Exhaust 1.02 0.10 mm (0.040 0.004 inch)
Hold the adjusting screw in place and tighten the locknut to a torque of 30 4 N m (22 3 lb ft).
Verify that the setting is correct.
Remove the timing bolt from the flywheel housing. Rotate the crankshaft for 360 degrees. Install the timing bolt in the flywheel housing.
With the No. 1 piston in the top center of the opposite stroke, perform Steps 1 through 9 for the remaining cylinders.
Remove the timing bolt from the flywheel housing.