GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Rocker Arms and Shafts

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REMOVAL & INSTALLATION



See Figures 1, 2 and 3

Buick Built Engines
  1. Disconnect the negative battery cable and remove the valve covers as previously outlined.
  2.  
  3. Remove the rocker arm shaft assembly bolts.
  4.  
  5. Remove the rocker arm shaft assembly and place it on a clean surface.
  6.  
  7. To remove the rocker arms from the shaft, you must first remove the nylon arm retainers. These can be removed with locking jaw pliers, by prying them out, or by breaking them by hitting them below the head with a chisel.
  8.  
  9. 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.
  10.  
  11. 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.
  12.  

To install:
  1. Install the rocker arms on the shaft and lubricate them with oil.
  2.  

Install the rocker arms for each cylinder only when the lifters are off the cam lobe and both valves are closed.

  1. Center each arm on the 1 / 4 in. (6.3mm) hole in the shaft. Install new nylon rocker arm retainers in the holes using a 1 / 2 in. (12.7mm) drift.
  2.  
  3. Locate the pushrods in the rocker arm cups and insert the shaft bolts. Tighten the bolts a little at a time to 30 ft. lbs. (41 Nm).
  4.  
  5. Install the valve covers using sealer or new gaskets as previously outlined in this section.
  6.  
  7. Start the engine and check for oil leaks.
  8.  



Click image to see an enlarged view

Fig. Fig. 1: Removing the nylon retainers on Buick engines

Chevrolet Built Engines
  1. Remove the rocker arm covers as previously outlined.
  2.  
  3. Remove the rocker arm nuts, rocker arm balls, rocker arms and push rods. Place the rocker arms, balls and push rods in a rack so they may be installed in the same locations.
  4.  

To install:

Whenever new rocker arms or rocker arm balls are being installed, coat the bearing surfaces of the rocker arms and rocker arm balls with Molykote® or it's equivalent.

  1. Install the push rods making sure they seat in the lifter socket.
  2.  
  3. Install the rocker arms, rocker arm balls and nuts. Tighten the rocker arm nuts until all lash is eliminated.
  4.  

Adjust the valves as follows:

  1. Crank engine until the mark on the harmonic balancer lines up with the center or "0" mark on the timing tab fastened to the crankcase front cover and the engine is in the No. 1 cylinder firing position. You can determine this by placing your fingers on the No. 1 valves as the mark on the harmonic balancer comes near the "0" mark on the timing tab. If the valves are not moving, the engine is in the No. 1 firing position. If the valves do move, the engine is on the No. 6 firing position (No. 4 on V6) and should be turned over one more time to reach the No. 1 position.
  2.  

The following valves may now be adjusted:



V8-Exhaust - 1, 3, 4, 8
 
V8-Intake - 1, 2, 5, 7
 
V6-Exhaust - 1, 5, 6
 
V6-Intake - 1, 2, 3
 

  1. Back out the adjusting nut until lash is felt at the push rod then turn in the adjusting nut until all lash is removed. This can be determined by rotating the push rod while turning the adjusting nut. Once the play has been removed, turn the adjusting nut one full turn to center the lifter plunger.
  2.  
  3. Crank engine one revolution until the mark on the harmonic balancer lines up with the center or "0" mark on the timing tab once again. The engine is now in the No. 6 (No. 4 on V6) cylinder firing position.
  4.  

The following valves may now be adjusted:



V8-Exhaust - 2, 5, 6, 7
 
V8-Intake - 3, 4, 6, 8
 
V6-Exhaust - 2, 3, 4
 
V6-Intake - 4, 5, 6
 

  1. Adjust these valves using the same procedure as the first set of valves.
  2.  
  3. Install the rocker arm covers and adjust the idle speed, if necessary.
  4.  



Click image to see an enlarged view

Fig. Fig. 2: Valve adjustment on Chevrolet engines

Oldsmobile and Pontiac Built Engines
EXCEPT DIESEL
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the valve cover.
  4.  
  5. Remove the rocker arm flanged bolts, and remove the rocker pivots.
  6.  
  7. Remove the rocker arms.
  8.  

Remove each set of rocker arms (one set per cylinder) as a unit.

To install:
  1. Position a set of rocker arms (for one cylinder) in the proper location.
  2.  

Install the rocker arms for each cylinder only when the lifters are off the cam lobe and both valves are closed.

  1. Coat the replacement rocker arm and pivot with SAE 90 gear oil and install the pivots.
  2.  
  3. Install the flanged bolts and tighten alternately. Torque the bolts to 25 ft. lbs. (34 Nm).
  4.  
  5. Install the valve cover, connect the negative battery cable, start the engine and check for oil leaks.
  6.  

DIESEL

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. Disconnect the negative battery cable.
  2.  
  3. Remove the valve cover.
  4.  
  5. Remove the rocker arm pivot bolts, the bridged pivot and rocker arms.
  6.  
  7. Remove each rocker set as a unit.
  8.  

To install:
  1. 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 valves when the engine is turned.
  2.  
  3. On 1980 and earlier models: The lifters can be bled down for six cylinders at once with the crankshaft in either of the following two positions:
    1. For cylinders numbered 3, 5, 7, 2, 4 and 8, turn the crankshaft so the saw slot on the harmonic balancer is at 0 degrees on the timing indicator.
    2.  
    3. For cylinders 1, 3, 7, 2, 4 and 6, turn the crankshaft so the saw slot on the harmonic balancer is at 4 o'clock.
    4.  

  4.  
  5. On these models only, tighten the rocker arm bolts on the numbered cylinders for the position the engine is in only. Torque to 28 ft. lbs. (35 Nm). It will take 45 minutes to completely bleed down the lifters. If additional lifters must be bled, wait till the 45 minutes has passed, and then turn the engine to the other position. Then tighten the remaining rocker arm pivot bolts and torque them to 28 ft. lbs. (35 Nm). Make sure you again wait 45 minutes before turning the crankshaft.
  6.  
  7. On 1981 and later models: Before installing any rockers, turn the crankshaft so No. 1 cylinder is at 32 degrees before Top Dead Center on the compression stroke. 32 degrees BTC is 50mm or 2 in. counterclockwise from the 0 degrees pointer. If only the right valve cover was removed for the work you did so that No. 1 cylinder's valves have not been disturbed you can determine that you're on the compression stroke for No. 1 by removing the glow plug for that cylinder and feeling for expulsion of air through that hole as you turn the engine (in the direction of normal rotation) up to the required position. If you have disturbed the rockers for No. 1, the left side valve cover will be off and you can rotate the crankshaft until the No. 5 cylinder intake valve pushrod ball is 7mm or 0.28 in. above the No. 5 cylinder exhaust pushrod ball. If this cover is off even if you did not disturb No. 1 cylinder, you may wish to use the pushrod measurement method to save time. Once the engine is in proper position, install the No. 5 cylinder rockers and rocker nuts, but DO NOT TIGHTEN THEM FULLY. Instead, turn them down by hand cautiously, alternating between intake and exhaust valves and turning both nuts an equal amount just until the intake valve nut begins to be harder to turn, indicating that the intake valve has just begun to crack open. Proceed cautiously so you don't turn too far. You'll see the valve begin to be depressed by the rocker, too.
  8.  
  9. At this point, torque all the remaining rocker nuts except those for cylinder No. 3. For cylinders No. 3 and 5, you'll have to turn the rocker bolts down very cautiously. On these cylinders, the cams are in such a position that installing the rocker nuts fully would open the valves all the way and then bend the pushrods. You'll have to feel very carefully for increased resistance as the valve reaches fully open position. Continue to turn the rocker nuts down on these three valves, always proceeding cautiously and stopping just as increased resistance is felt. Alternate, giving some time between tightening operations for the lifters to bleed down somewhat, until you can torque the nuts smoothly (without a sudden increase in resistance) to the required 28 ft. lbs. (35 Nm). Now, wait a full 45 minutes before the crankshaft is turned for any reason to permit all the lifters to bleed down fully.
  10.  
  11. Assemble the remaining components in reverse of disassembly. The rocker covers do not use gaskets, but are sealed with a bead of Room Temperature Vulcanizing (RTV) silicone sealer.
  12.  
  13. Connect the negative battery cable, start the engine and check for oil leaks.
  14.  



Click image to see an enlarged view

Fig. Fig. 3: Rocker arm positioning; Buick shown

 
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