GM Storm/Spectrum 1985-1993 Repair Guide

Camshaft and Bearings

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REMOVAL & INSTALLATION



Spectrum

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. Align the crankshaft pulley notch with the 0 degree mark on the timing cover.
  4.  
  5. Remove the cylinder head cover.
  6.  
  7. Remove the timing cover.
  8.  
  9. Loosen the camshaft timing gear bolts; Be careful not rotate the engine.
  10.  
  11. Loosen the timing belt tensioner and remove the timing belt from the camshaft timing gear.
  12.  
  13. Remove the rocker arm shaft/rocker arm assembly. Remove the timing gear from the camshaft.
  14.  
  15. Remove the distributor bolt and the distributor.
  16.  
  17. Remove the camshaft and the camshaft seal.
  18.  
  19. To install, drive a new camshaft seal on the camshaft using the seal installation tool No. J-35268 or equivalent, reverse the removal procedures, adjust the valves and the timing belt.
  20.  



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Fig. Fig. 1: Remove the camshaft and seal from the cylinder head - Spectrum

Storm

See Figures 2, 3 and 4

  1. Disconnect the battery negative cable.
  2.  
  3. Remove the cylinder head cover.
  4.  
  5. Rotate the crankshaft to position No. 1 at TDC on its compression stroke by aligning the camshaft(s) pulley timing mark with the cylinder head cover.
  6.  
  7. Loosen the timing belt tensioner.
  8.  
  9. Remove the timing belt pulley(s) from the camshaft(s).
  10.  
  11. Remove the distributor.
  12.  

When removing the camshaft bearing caps, be sure to note location and orientation of all the caps to assure they are reinstalled in the same positions. On some engines the caps may be numbered, labelled (E or I for exhaust or Intake) and/or may contain arrows showing proper direction for installation.

  1. Remove the camshaft(s) bearing cap bolts, starting at the center and moving outward, then remove the camshaft and seal from the vehicle. Discard seal.
  2.  
  3. Reverse procedure to install. For the DOHC engines, apply sealant to the appropriate points on the bearing caps as shown. Torque the camshaft bearing cap bolts to 89 inch lbs. (10 Nm). Connect the battery negative cable. Start the engine and check for leaks.
  4.  



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Fig. Fig. 2: Check to see if the camshaft bearing caps are labelled like this one, to assure installation in the proper positions. If necessary, arrange and/or tag the caps to assure proper orientation



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Fig. Fig. 3: Camshafts and bearing caps - Storm DOHC engines



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Fig. Fig. 4: For the DOHC camshafts apply sealant to these points on the exhaust No. 1, intake No. 2 and both No. 5 bearing caps

INSPECTION



See Figures 5 through 11

  1. Clean the camshaft in solvent and allow to dry.
  2.  
  3. Inspect the camshaft for obvious signs of wear: scores, nicks or pits on the journals or lobes. Light scuffs or nicks can be removed with an oil stone.
  4.  
  5. Position the camshaft in V-blocks with the front and rear journals riding on the blocks. Check if the camshaft is bent using a dial indicator on the center bearing journal. The run-out limit at the center journal is 0.00394 in. (0.1mm). Replace the camshaft if run-out is excessive.
  6.  
  7. Using a micrometer, measure the camshaft lobe heights and compare to specification and each other to check for excessive or uneven wear. Replace a SOHC camshaft if any lobes have a height of less than 1.426 in. (36.22mm) for 1985-92 vehicles or 1.399 in. (35.54mm) on intake lobes and 1.413 in. (35.89mm) on exhaust lobes for 1993 vehicles. Replace a DOHC camshaft if any lobe heights are less than 1.503 in. (38.17mm) for 1.6L DOHC engines or 1.531 in. (38.9mm) for the 1.8L DOHC engine. Compare the measurements of all the camshaft's lobes. Replace a camshaft whose wear deviates more than 0.00197 in. (0.05mm).
  8.  
  9. Using a micrometer, measure the diameter of the journals and replace any camshaft containing a journal that is less than the minimum or that contains uneven wear. For all engines, journal diameter should be greater than 1.0157 in. (25.8mm). As with the lobe height measurements, replace a camshaft whose journal wear deviates more than 0.00197 in. (0.05mm).
  10.  
  11. Measure the bearing oil clearance using a plastic-type gauging material. Temporarily install the camshaft to the cylinder head. Place a strip of the gauge material on the top of each journal, then install the bearing caps and tighten to 89 inch lbs. (10 Nm). DO NOT ROTATE THE CAMSHAFT or the measurement will be ruined and the process must be repeated. Remove the bearing caps and compare the width of the strip to the gauge. If the gauging material reveals an oil clearance of more than 0.0059 in. (0.15mm), the camshaft and/or the cylinder head must be replaced.
  12.  
  13. With the camshaft and bearing cap temporarily installed, mount a dial gauge to 1 end of the camshaft in order to measure thrust clearance. Carefully pry on the other end of the camshaft or on either side of the journals to slide the camshaft back and forth against the dial gauge. Replace camshaft and/or cylinder head if the thrust clearance is greater than 0.008 in. (0.2mm).
  14.  
  15. Finally, measure the width of the distributor slot located in the end of the camshaft (exhaust shaft on DOHC engines). Replace the camshaft if slot width is greater than 0.196 in. (5mm).
  16.  



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Fig. Fig. 5: Measure camshaft run-out at the center bearing journal using a dial gauge



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Fig. Fig. 6: Measure the camshaft lobe height using an outside micrometer



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Fig. Fig. 7: Measure camshaft journal diameter using an outside micrometer



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Fig. Fig. 8: Apply a strip of plastic-type gauging material to the top of each journal



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Fig. Fig. 9: After tightening, then removing the bearing caps, compare the plastic material width to the gauge in order to determine journal oil clearance



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Fig. Fig. 10: Mount a dial gauge on the end of the camshaft to measure thrust clearance



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Fig. Fig. 11: Measure the distributor slot width in the end of the camshaft

 
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