WASHER 8T4896 - Caterpillar

Bridge Adjustment (If Equipped)
When the head is disassembled, keep the bridges with the respective cylinders. Adjustment of the bridge will be necessary for the following reasons.
Grinding the engine's valves
Resurfacing or reconditioning the engine's cylinder headThe bridge should be checked and/or adjusted when the valves have been adjusted. Use the procedure that follows to make an adjustment to the bridge.
Illustration 1 g00363479
Bridge adjustmentNote: Valves must be fully closed.
Apply engine oil on the bridge dowel in the cylinder head. Apply engine oil in the bore in the bridge.
Install the bridge with the adjustment screw toward the exhaust manifold.
Loosen the locknut for the adjustment screw. Loosen the adjustment screw for several turns.
Put a force on the bridge with a finger. This will keep the bridge in contact with the valve stem opposite the adjustment screw.
Turn the adjustment screw clockwise until the adjustment screw makes contact with the valve stem. Then, turn the adjustment screw 20 to 30 degrees more in a clockwise direction. This will make the bridge straight on the dowel. Also, this will make compensation for the clearance in the threads of the adjustment screw.
Hold the adjustment screw in this position. Tighten the locknut to 47 9 N m (35 7 lb ft).
Use clean engine oil to lubricate the contact points of the bridge assembly and the rocker arm. Valve Lash Setting
Valve lash is measured between the rocker arm and the bridge for the inlet valves. Valve lash is measured between the rocker arm and the valve stem for the exhaust valve. All of the clearance measurements and the adjustments must be made with the engine stopped. The valves must be fully closed. Valve Lash Check
An adjustment is not necessary if the measurement of the valve lash is in the acceptable range. The ranges are given in the following tables.
Table 1
Quick Reference for Engine Valve Lash Setting
3408 Engines    
   Inlet Valves    Exhaust Valves    
Valve Lash Setting    
0.28 to 0.48 mm (0.011 to 0.019 inch)    
0.66 to 0.86 mm (0.026 to 0.034 inch)    
TC Compression Stroke     1-2-5-7     1-3-4-8    
TC Exhaust Stroke (1)     3-4-6-8     2-5-6-7    
Firing Order     1-8-4-3-6-5-7-2 (2)    
( 1 ) 360° from TC compression stroke
( 2 ) Refer to the following illustration in order to locate the No. 1 cylinder.
Table 2
Quick Reference for Engine Valve Lash Setting
3412 Engines    
   Inlet Valves    Exhaust Valves    
Valve Lash Setting    
0.28 to 0.48 mm (0.011 to 0.019 inch)    
0.66 to 0.86 mm (0.026 to 0.034 inch)    
TC Compression Stroke     1-3-4-6-7-12     1-4-5-8-9-12    
TC Exhaust Stroke (1)     2-5-8-9-10-11     2-3-6-7-10-11    
Firing Order     1-4-9-8-5-2-11-10-3-6-7-12 (2)    
( 1 ) 360° from TC compression stroke
( 2 ) Refer to the following illustration in order to locate the No. 1 cylinder.Note: The inlet and exhaust valve lash adjustments should be made at the first recommended oil change. Refer to Operation And Maintenance Manual for subsequent intervals.Valve Lash Adjustment
Illustration 2 g01015545
Cylinder and valve