GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Rocker Arms

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4 and 5

All Gasoline Engines, Except 231 V6

To access the rocker arms, first remove the rocker arm covers. With the covers removed, loosen and remove the adjusting nuts and the rocker arm pivots. The rocker arms are then free to be removed from the cylinder head studs. Be sure to adjust the valve lash after replacing the rocker arms. Coat the replacement rocker arm and ball with SAE 90 gear oil before installation. Make sure the valves are closed on the cylinder you are working on before installation.

When replacing an exhaust rocker, move an old intake rocker to the exhaust rocker arm stud and install the new rocker arm on the intake stud. This will prevent burning of the new rocker arm on the exhaust position.

Rocker arms studs that have damaged threads or are loose in the cylinder heads may be replaced by reaming the bore and installing oversize studs. Oversizes available are 0.003 in. and 0.013 in. The bore may also be tapped and screw-in studs installed. Several aftermarket companies produce complete rocker arm stud kits with installation tools. Mark IV and late high performance small block engines use screw-in studs and pushrod guide plates.



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Fig. Fig. 1: The rocker covers must be removed in order to access the rocker arms



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Fig. Fig. 2: Use a ratchet to loosen the rocker arm adjusting nuts



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Fig. Fig. 3: Remove the rocker arm nut and pivot, then the rocker arm will be free for removal



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Fig. Fig. 4: Lift the rocker arm from the stud



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Fig. Fig. 5: Rocker arm components for the inline 6-cylinder engine (most V8's similar)

231 V6 Engines

See Figures 6, 7, 8, 9 and 10

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the rocker arm covers.
  4.  
  5. Remove the rocker arm shaft assembly bolts.
  6.  
  7. Remove the rocker arm shaft assembly.
  8.  

It may be easier to remove the nylon arm retainers with the rocker arm shafts still installed to the cylinder head

  1. To remove the rocker arms from the shaft, the nylon arm retainers must be removed. They can be removed with a pair of water pump pliers, or they can be broken by hitting them below the head with a chisel.
  2.  
  3. Remove the rocker arms from the shaft. Make sure you keep them in order. Also note that the external rib on each arm points away from the rocker arm shaft bolt located between each pair of rocker arms.
  4.  

To install:
  1. If you are installing new rocker arms, note that the replacement rocker arms are marked R and L for right and left side installation. Do not interchange them.
  2.  
  3. Install the rocker arms on the shaft, as noted, and lubricate them with oil.
  4.  
  5. Center each arm on the 1 / 4 in. hole in the shaft. Install new nylon rocker arm retainers in the holes using a 1 / 2 in. drift.
  6.  
  7. Install the shaft to the cylinder head while locating the push rods in the rocker arms, then insert the shaft bolts. Tighten the bolts a little at a time until they are tight.
  8.  
  9. Install the rocker covers using new gaskets.
  10.  
  11. Connect the negative battery cable.
  12.  



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Fig. Fig. 6: Removing the rocker arm nylon retainers-231 V6 rocker shafts



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Fig. Fig. 7: Loosen the rocker shaft retaining bolts using a ratchet



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Fig. Fig. 8: Remove the shaft retaining bolts in order to free the shaft assembly



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Fig. Fig. 9: With the bolts removed, the shaft and rocker arm assembly is free to be removed from the cylinder head



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Fig. Fig. 10: When replacing the rocker arms take note of the markings for proper installation-231 V6 engine

V6 and V8 Diesel Engines

When the diesel engine rocker arms are removed or loosened, the lifters must be bled down to prevent oil pressure buildup inside each lifter, which could cause it to raise up higher than normal and bring the valves within striking distance of the pistons.

  1. Remove the valve cover.
  2.  
  3. Remove the rocker arm pivot bolts, the bridged pivot and rocker arms.
  4.  
  5. Remove each rocker set as a unit.
  6.  
  7. To install, lubricate the pivot wear points and position each set of rocker arms in its proper location. Do not tighten the pivot bolts for fear of bending the pushrods when the engine is turned. Bleed-down the valve lifters.
  8.  

Diesel Engine Bleed-Down
  1. Before installing any removed rocker arms, rotate the crankshaft so that No. 1 cylinder is 32°BTDC. This is 50mm (2 in.) counterclockwise from the 0 degree pointer on the timing indicator on the front of the engine. If only the right valve cover was removed, remove the glow plug from No. 1 cylinder to determine if the piston is in the correct position. If the left valve cover wash removed, rotate the crankshaft until the No. 5 cylinder intake valve pushrod ball is 7.0mm (0.28 in.) above the No. 5 cylinder exhaust valve pushrod ball.
  2.  


WARNING
Use only hand wrenches to torque the rocker arm pivot bolts to avoid pushrod damage.

  1. If the No. 5 cylinder pivot and rocker arms were removed, install them. Torque the bolts alternately between the intake and exhaust valves until the intake valve begins to open, then stop.
  2.  
  3. Install the remaining rocker arms except No. 3 exhaust valve for (V6) or No. 3 and No. 8 intake valves for (V8), if these rockers were removed.
  4.  
  5. If removed, install the No. 3 valve pivots, but do not torque them beyond the point that the valve would be fully open. This is indicated by a strong resistance while still turning the pivot retaining bolts. Going beyond this will bend the pushrod. Torque the bolts slowly, allowing the lifter to bleed-down.
  6.  
  7. Finish torquing the No. 5 cylinder rocker arm pivot bolt slowly. Do not go beyond the point that the valve would be fully open. this is indicated by a strong resistance while still turning the pivot retaining bolts. Going beyond this will bend the pushrod.
  8.  
  9. DO NOT turn the engine crankshaft for at least 45 minutes, allowing the lifters to bleed-down. This is important.
  10.  
  11. Finish reassembling the engine as the lifters are being bled.
  12.