Chevrolet Blazer/Jimmy 1969-1982 Repair Guide

Camshaft

Print

REMOVAL & INSTALLATION



Six Cylinder Engines
1969-77 MODELS
  1. Remove the grille and radiator. Remove the timing gear cover.
  2.  
  3. Remove the valve cover and gasket, loosen all the valve rocker arm nuts and pivot the arms clear of the pushrods.
  4.  
  5. Remove the distributor and fuel pump.
  6.  
  7. Remove the coil (without HEI), side cover and gasket. Remove the pushrods and valve lifters. Keep them in order for reinstallation.
  8.  
  9. Align the timing gear marks and remove the two camshaft thrust plate retaining screws by working through the holes in the camshaft gear.
  10.  
  11. Remove the camshaft and gear assembly by pulling it out through the front of the block. Be careful not to dislodge the camshaft bearings.
  12.  

If replacing either the camshaft or 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 .001 to .005 inch.

To install:

  1. Install the camshaft assembly in the engine.
  2.  

Pre-lube the cam lobes with an engine assembly lubricant. Do not dislodge the cam bearings when inserting the camshaft.

  1. Turn the crankshaft and camshaft to align and bring the timing marks together. Push the camshaft into this aligned position.
  2.  
  3. Runout on the camshaft gear should not exceed .004 inch. Crankshaft gear runout should not exceed .003 inch.
  4.  
  5. Backlash between the two gears should be between .004 and .006 inch.
  6.  
  7. Install the timing gear cover and gasket.
  8.  
  9. Install the oil pan and gaskets, if removed.
  10.  
  11. Install the harmonic balancer.
  12.  
  13. Line up the keyway in the balancer with the key on the crankshaft and press the balancer onto the shaft until it bottoms against the crankshaft gear.
  14.  
  15. Install the valve lifters and pushrods. Install the side cover with a new gasket. Attach the coil wires; install the fuel pump.
  16.  
  17. Install the distributor and set the timing. Refer to the distributor removal & installation procedure in this section.
  18.  
  19. Pivot the rocker arms over the pushrods and 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.
  26.  
  27. Fill the cooling system, start the engine and check for leaks.
  28.  
  29. Check and adjust the ignition timing.
  30.  

1978-82 MODELS

When removing the camshaft on all 1978 and later models, the radiator support will, in all probability, be in the way. To remove it requires extensive disassembly of the front end, including the battery tray, fan shroud, grille and headlight assemblies, fenders and fender skirts. In the long run, it's probably easier to take out the engine.

  1. Remove the engine as previously outlined in this section.
  2.  
  3. Remove the rocker arm cover.
  4.  
  5. Loosen the rocker arms enough to allow removal of the pushrods. Organize the rods in a safe place as they must be installed in their original positions.
  6.  
  7. Mark the distributor housing at the no. 1 and no. 6 spark plug tower position. Disconnect the spark plug wires at the plugs and remove the distributor cap.
  8.  
  9. Slowly turn the engine over until the distributor rotor points to the no. 1 position.
  10.  
  11. Disconnect the distributor lead at the coil, remove the distributor hold-down bolts and remove the distributor.
  12.  
  13. Remove the pushrod covers.
  14.  
  15. Remove the valve lifters and organize them in a safe place as they must be installed in their original positions.
  16.  
  17. Remove the front cover as previously outlined.
  18.  
  19. Remove the fuel pump.
  20.  
  21. Refer to step 5-17 of the Six Cylinder Through 1977 procedure, in this section.
  22.  
  23. Install the engine as previously outlined.
  24.  

V8 Gasoline Engines
  1. Remove the intake manifold and timing chain cover as previously described. Remove the rocker arm covers and gaskets, loosen all the rocker arm nuts and pivot the arms clear of the pushrods. Remove the pushrods and valve lifters, keeping them in order for reinstallation.
  2.  
  3. Remove the grille and radiator.
  4.  
  5. Remove the fuel pump and pump pushrod.
  6.  
  7. Remove the camshaft sprocket bolts, sprocket and timing chain. A light blow to the lower edge of a tight sprocket should free it (use a plastic mallet).
  8.  
  9. Install two 5 / 18 -18;TS4 inch bolts in the camshaft bolt holes and pull it from the block.
  10.  
  11. To install, reverse the removal procedure aligning the timing marks.
  12.  

Pre-lube the cam lobes with engine assembly lubricant. Do not dislodge the cam bearings when installing the camshaft.

Diesel Engines

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

  1. Disconnect the batteries, raise the car and drain the cooling system.
  2.  
  3. Disconnect the exhaust pipe at the manifolds.
  4.  
  5. Remove the fan shroud, the fan and the radiator. Lower the vehicle.
  6.  
  7. Remove the vacuum pump and the intake manifold.
  8.  
  9. Remove the injection lines. Cap all lines, nozzles and fittings.
  10.  
  11. Remove the water pump and then remove the injection pump gear.
  12.  
  13. Scribe a mark on the front cover aligning the pump flange and the cover.
  14.  
  15. Remove the injection pump, the power steering pump and the alternator.
  16.  
  17. If equipped with AC, remove the compressor and position it out of the way.
  18.  
  19. Remove the rocker arm covers, the rocker arm shaft assembly and the pushrods. Place parts in a rack so they may be installed in the original location.
  20.  
  21. Remove the thermostat housing/crossover from the cylinder heads.
  22.  
  23. Remove the cylinder head with the exhaust manifolds attached.
  24.  
  25. Remove the valve lifter clamps, guide plates and valve lifters. Keep parts in order so they may be installed in the original location.
  26.  
  27. Remove the front cover.
  28.  
  29. Remove the timing chain.
  30.  
  31. Remove the fuel pump and the cam retainer plate.
  32.  
  33. If equipped with AC, remove the condenser mounting bolts and lift out the condenser. This may require some assistance.
  34.  
  35. Remove the camshaft.
  36.  

To install:

Whenever a new camshaft is installed, it is a good idea to replace the valve lifters, oil and filter to insure durability of the cam lobes and lifters. Coat the cam lobes with Molycote.

  1. Lubricate the cam journals with engine oil and install the camshaft.
  2.  
  3. Install the retainer plate, fuel pump and timing chain.
  4.  
  5. Install the front cover, valve lifters, guide plates and clamps.
  6.  
  7. Install the cylinder head, pushrods and rocker arm shaft assemblies.
  8.  
  9. Install the rocker arm covers.
  10.  
  11. Install the injection pump to the front cover making sure the marks are in alignment.
  12.  
  13. Install the injection pump driven gear making sure the marks are aligned.
  14.  
  15. Install the water pump and fuel injection lines.
  16.  
  17. Install the alternator, the power steering and the AC.
  18.  
  19. Install the crankshaft pulley and the fan. Install and adjust all drive belts as necessary.
  20.  
  21. Install the fan shroud and the radiator. Fill the system with coolant.
  22.  
  23. Connect all necessary wires and hoses.
  24.  
  25. Raise the car, connect the exhaust pipes to the manifolds and then lower the car.
  26.  
  27. Install the vacuum pump and intake manifold.
  28.  
  29. Start the engine and check for leaks.
  30.  

 
label.common.footer.alt.autozoneLogo