GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Camshaft

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REMOVAL & INSTALLATION



See Figure 1

Inline 6-Cylinder

Due to the length of the inline 6-cylinder camshaft, a large amount of working room will be required in front of the engine to remove the camshaft. There are two ways to go about this task: either remove the engine from the car, or remove the radiator, grille and all supports which are mounted directly in front of the engine. If the second alternative is chosen, you must also disconnect the motor mounts and raise the front of the engine.

  1. Either remove the engine from the vehicle, or remove the radiator, grille and supports.
  2.  
  3. Remove the timing cover assembly from the vehicle.
  4.  
  5. Remove the valve cover and gasket, loosen all the valve rocker arm nuts and pivot the arms clear of the pushrods.
  6.  
  7. Remove the distributor and the fuel pump.
  8.  
  9. Remove the coil, the side cover and its gasket. Remove the pushrods and valve lifters.
  10.  
  11. Remove the two camshaft thrust plate retaining screws by working through the holes in the camshaft gear.
  12.  
  13. Remove the camshaft and gear assembly by pulling it out through the front of the block.
  14.  

If replacing either the camshaft or the camshaft gear, the gear must be pressed off the camshaft. The replacement parts must be assembled in the same manner (under pressure). In placing the gear on the camshaft, press the gear onto the shaft until it bottoms against the gear spacer ring. The end clearance of the thrust plate should be 0.001-0.005 in.

To install:
  1. Install the camshaft assembly in the engine.
  2.  

Pre-lube the cam lobes with E.O.S. or SAE 90 gear lubricant. Do not dislodge the cam bearings when inserting the camshaft.

  1. Turn the crankshaft and the camshaft to align the timing marks together. Push the camshaft into this aligned position. Install the camshaft thrust plate-to-block screws and torque them to 6-7 1 / 2 ft. lbs. (8-10 Nm).
  2.  
  3. Runout on either the crankshaft or the camshaft gear should not exceed 0.003 in.
  4.  
  5. Backlash between the two gears should be between 0.004-0.006 in.
  6.  
  7. Install the timing gear cover and its gasket.
  8.  
  9. Install the oil pan and gaskets.
  10.  
  11. Install the harmonic balancer.
  12.  
  13. Line up the keyway in the balancer with the key on the crankshaft and the drive balancer onto the shaft until it bottoms against the crankshaft gear.
  14.  
  15. Install the valve lifters and pushrods. Install the side cover with new gasket. Attach the coil wires; install the fuel pump.
  16.  
  17. Install the distributor and set the timing as described under distributor installation at the beginning of this section.
  18.  
  19. Pivot the rocker arms over the pushrods and then adjust the valves.
  20.  
  21. Add oil to the engine. Install and adjust the fan belt.
  22.  
  23. Install the radiator or shroud.
  24.  
  25. Install the grille assembly and connect the negative battery cable.
  26.  
  27. Fill the cooling system, start the engine and check for leaks.
  28.  
  29. Check and adjust the timing.
  30.  



Click image to see an enlarged view

Fig. Fig. 1: When removing the camshaft, be careful to pull straight back so as not to damage the camshaft journals or bearings

Gasoline V6 and V8 (except 231 V6)
  1. Remove the timing chain and camshaft sprocket from the engine. For details, refer to the timing chain procedure found earlier in this section.
  2.  

If the camshaft sprocket is tight on the camshaft, use a plastic hammer to carefully bump it loose.

  1. On the V8, remove the oil cooler lines and the hoses from the radiator, then remove the radiator from the vehicle.
  2.  
  3. Remove the intake manifold and the rocker arm covers.
  4.  
  5. If equipped on the V8, remove the AIR pump bracket.
  6.  
  7. On the V8, disconnect the fuel lines at the fuel pump, then remove the fuel pump assembly.
  8.  
  9. If equipped with air conditioning on the V8, remove the compressor and the condenser, then reposition them aside with the lines intact.
  10.  
  11. Remove the rocker arm assemblies, then remove the push rods and the valve lifters.
  12.  

If components of the valve train are to be reused, be sure to sort or label them to assure installation in their original locations.

  1. Install two 5 / 16 -18 x 4 in. bolts in the camshaft and carefully pull it from the front of the engine while rotating it back and forth.
  2.  

When removing or replacing the camshaft, be careful not to damage the camshaft bearings.

To install:
  1. Coat the camshaft journals and lobes with clean engine oil or with an approved pre-lube.
  2.  
  3. Carefully guide the camshaft into the engine block and through the bearings.
  4.  
  5. Install the valve lifters, pushrods and rocker arm assemblies, then adjust the valves.
  6.  
  7. If applicable, reposition and secure the A/C compressor and condenser.
  8.  
  9. If equipped, install the V8 engine's air pump bracket.
  10.  
  11. Install the intake manifold and the rocker arm covers. If the engine is equipped with solid lifters, do not bolt the covers in place at this time.
  12.  
  13. On the V8, install the radiator assembly to the vehicle, then install the hoses and oil cooler lines.
  14.  
  15. Install the timing chain and camshaft sprocket to the engine.
  16.  
  17. If the engine is equipped with solid lifters, make a final valve clearance adjustment with the engine running, then secure the rocker covers to the cylinder heads.
  18.  

231 V6
  1. Disconnect the negative battery cable, then drain the engine cooling system.
  2.  
  3. Disconnect the hoses and remove the radiator.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the water pump and all the drive belts. Remove the alternator assembly.
  2.  
  3. Remove the crankshaft pulley and the vibration damper.
  4.  
  5. Remove the intake manifold. Mark the location of the distributor and remove the distributor.
  6.  
  7. Remove the fuel pump. Remove the timing chain cover and the oil pump.
  8.  
  9. Remove the timing chain and the camshaft sprocket, along with the distributor drive gear and the fuel pump eccentric.
  10.  
  11. Remove the rocker arm covers and the rocker arm assemblies. Mark the pushrods and remove them. Remove the lifters. mark them so they can be returned to their original position.
  12.  
  13. Carefully remove the camshaft from the engine. Make sure you don't damage the bearings.
  14.  

To install:
  1. Coat the camshaft journals and lobes with clean engine oil or with an approved pre-lube.
  2.  
  3. Carefully insert the camshaft to the engine, taking care not to damage the bearings.
  4.  
  5. Install the lifters and pushrods. If these components are being reused, they must be installed in their original locations.
  6.  
  7. Install the rocker arm assemblies and adjust the valves.
  8.  
  9. Install the timing chain and camshaft sprocket, along with the distributor drive gear and the fuel pump eccentric.
  10.  
  11. Install the fuel pump assembly.
  12.  
  13. Remember to pack the oil pump with petroleum jelly, then install the timing chain cover and oil pump.
  14.  
  15. Install the intake manifold and install the distributor (while aligning the matchmarks made earlier).
  16.  
  17. Install the crankshaft pulley and the vibration damper.
  18.  
  19. Install the alternator assembly, water pump and all the drive belts.
  20.  
  21. Install the radiator and hoses, then connect the negative battery cable and properly refill the engine cooling system.
  22.  

V6 and V8 Diesel Engines

See Figure 2

If equipped with air conditioning, the system must be discharged and recovered by an air conditioning specialist before the camshaft is removed. The condenser must also be removed from the car. Removal of the camshaft also requires removal of the injection pump drive and driven gears, removal of the intake manifold, disassembly of the valve lifters, and re-timing of the injection pump.

  1. Disconnect the negative battery cables, then drain the coolant and remove the radiator.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the intake manifold along with the gasket, front and rear intake manifold seals. For details, refer to the intake manifold removal and installation procedures earlier in this section.
  2.  
  3. Remove the crankshaft damper pulley and damper. Do NOT use a jawed type puller or the balancer will likely be destroyed.
  4.  
  5. Remove the rocker covers, then remove the rocker arms, pushrods and valve lifters. Be sure to keep the parts in order to that they may be returned to their original position.
  6.  
  7. Remove the camshaft sprocket retaining bolt, and remove the timing chain and sprockets.
  8.  
  9. Position the camshaft dowel pin at the 3 o'clock position on the V8.
  10.  
  11. On V8s, push the camshaft rearward and hold it there, but be careful not to dislodge the oil gallery plug at the rear of the engine. Remove the fuel injection pump drive gear by sliding it from the camshaft while rocking the pump driven gear.
  12.  
  13. To remove the fuel injection pump driven gear, remove the pump adapter, the snapring, and remove the selective washer. Remove the driven gear and spring.
  14.  



Click image to see an enlarged view

Fig. Fig. 2: Diesel injection pump drive gear

  1. Remove the camshaft by sliding it out the front of the engine. On the V6, install a longer bolt into the front hole on the camshaft, to act as a handle. Be extremely careful not to allow the cam lobes or journals to contact any of the bearings this could result in bearing damage or dislodgment. Do not force the camshaft to move at any time during removal, or bearing damage will result.
  2.  

To install:
  1. If either the injection pump drive or driven gears are to be replaced, replace both gears.
  2.  
  3. Coat the camshaft and the cam bearings with a heavy-weight engine oil, GM lubricant #1052365 or the equivalent.
  4.  
  5. Carefully slide the camshaft into position in the engine.
  6.  
  7. Fit the crankshaft and camshaft sprockets, aligning the timing marks as shown in the timing chain removal and installation procedures, above. Remove the sprockets without disturbing the timing.
  8.  
  9. Install the injection pump driven gear, spring, shim, and snapring. Check the gear end-play. If the end-play is not within 0.002-0.006 in. on V8s through 1979 and 0.002-0.015 in. on 1980-84 engines, replace the shim to obtain the specified clearance. Shims are available in 0.003 in. increments, from 0.008-0.0115 in.
  10.  
  11. Position the camshaft dowel pin at the 3 o'clock position. Align the zero marks on the pump drive gear and pump driven gear. Hold the camshaft in the rearward position and slide the pump drive gear onto the camshaft. Install the camshaft bearing retainer.
  12.  
  13. Install the timing chain and sprockets, making sure the timing marks are aligned.
  14.  
  15. Install the lifters, pushrods, and rocker arms. Refer to the rocker arm procedures earlier in this section for lifter bleed-down procedures. Failure to bleed-down the lifters could bend valves when the engine is turned over.
  16.  
  17. Install the injection pump adapter and injection pump. Refer to the appropriate procedures under the Fuel System section of this information.
  18.  
  19. If not done already, install the rocker arm covers.
  20.  
  21. Install the crankshaft damper and pulley.
  22.  
  23. Install the intake manifold using new gaskets and seals.
  24.  
  25. Install the radiator assembly and connect the hoses.
  26.  
  27. Connect the negative battery cables, then properly refill the engine cooling.
  28.  
  29. Run the engine and check for leaks.
  30.  

CAMSHAFT INSPECTION



Completely clean the camshaft with solvent, paying special attention to cleaning the oil holes. Visually inspect the cam lobes and bearing journals for excessive wear. If the lobe is questionable, have the cam checked at a reputable machine shop; if a journal or lobe is worn, the camshaft must be reground or replaced. Also have the camshaft checked for straightness on a dial indicator.

If a cam journal is worn, there is a good chance that the bushings are worn.

 
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