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1. Lock nut

2. Adjusting screw

3. Push rod

Figure 3-7. Adjusting Tappets

Wet Hydraulic Unit

If the push rod hydraulic unit is under oil supply conditions, that is, has not been removed from the engine and cleaned, use the following procedure:

With tappet in its lowest position, loosen locknut (1) and turn adjusting screw (2) upward, shortening push rod, until push rod has noticeable shake. Keep push rod from turning by holding with wrench on flats at base of push rod. Slowly turn adjusting screw downward, lengthening rod, until all shake has been taken up. Mark adjusting screw with cha Ik and turn it down exactly four full turns. Lock adjustment by tightening locknut (1) to 10 ft-lbs torque. Be sure to allow hydraulic unit to bleed down before turning engine over to adjust next tappet. Usually, hydraulic unit will bleed down in 5 to 10 minutes.

CAUTION — Turning engine over before hydraulic unit bleeds down may cause valve interference resulting in damaged push rods or valves.

When push rod can be rotated with finger tips, hydraulic unit has bled down sufficiently and engine may be turned over to adjust next tappet.

Dry Hydraulic Unit

If hydraulic unit is dry, that is clean and free of oil, set tappet at its lowest point before inserting dry hydraulic unit.

Install push rod and turn adjusting screw (2) downward until hydraulic unit piston bottoms in its bore. Turn adjusting screw (2) upward exactly 1 -3/4 turns. Lock adjustment by tightening locknut (1) to 10ft-lbs torque. When using this method, bleed down is not required before proceeding to next tappet.

Turn engine over until next tappet is at its lowest point before inserting next dry hydraulic unit. Adjust push rod length as described above. Continue in this manner until all tappets are adjusted. Make sure hydraulic unit is clean and dry before adjusting push rod length.

Install push rod cover spring cap retainers.

Always use new push rod cover gaskets at all joints. Clean gasket surfaces with greaseless solvent. Greasy gaskets or surfaces will cause gaskets to adhere to joint surfaces and become difficult to remove without damaging joint surfaces.

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