Nissan Z - ZX 1970-1988 Repair Guide

Valve Guides

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REMOVAL & INSTALLATION



Except VG Engines

See Figures 1 and 2

  1. Refer to the Valve Springs removal and installation procedures in this section, and remove the valve springs.
  2.  
  3. Using an hydraulic press and the Valve Guide Removal tool No. ST11320000, remove the guides that are excessively worn. This requires a press with about two tons of pressure; press toward the rocker arm cover side.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Remove the valve guide from the cylinder head



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Fig. Fig. 2: Reaming the valve guide bore-1970-83 models

Removing the valve guides is easier to perform if the cylinder head is heated before attempting it.

  1. If using heat, allow the head to cool to room temperature and ream the guide hole to 12.176-12.197mm.
  2.  
  3. Heat the cylinder head to 302-392°F (150-200°C), then press 0.2mm oversize guides into the head. Interference fit of the guide should be 0.027-0.049mm.
  4.  
  5. Using the Valve Guide Reamer tool No. ST11081000, ream the bore of the new guides to 8.000-8.018mm.
  6.  
  7. Correct the valve seat surface as described in the Valve Seat removal and installation procedures if a new seat is not required.
  8.  
  9. To install, use new gaskets, valve guide seals and reverse the removal procedures.
  10.  

VG Engines

See Figures 3 and 4

  1. Refer to the Valve Springs removal and installation procedures in this section, and remove the valve springs.
  2.  
  3. Heat the cylinder head to at least 320°F, then drive out the guide using an arbor press or a hammer and drift punch.
  4.  



Click image to see an enlarged view

Fig. Fig. 3: Removing the valve guide-1984-88 models



Click image to see an enlarged view

Fig. Fig. 4: Reaming the valve guide bore-1984-88 models

Drive the valve guides toward the rocker arm cover side of the cylinder head.

  1. With the valve guides removed, ream the cylinder head valve guide hole (inside diameter) to:
    1. Intake: 11.175-11.196mm
    2.  
    3. Exhaust: 12.175-12.196mm
    4.  

  2.  
  3. Heat the cylinder to at least 320°F and press the service valve guide onto the cylinder head.
  4.  
  5. Ream the valve guide (inside diameter) to:
    1. Intake: 7.000-7.018mm
    2.  
    3. Exhaust: 8.000-8.018mm
    4.  

  6.  
  7. To install, use new gaskets, valve guide seals and reverse the removal procedures.
  8.  

INSPECTION



A worn valve guide may be reconditioned by a process known as knurling: This is a process where the inner surface of the guide is raised, thus creating a smaller diameter bore. To have this procedure performed, consult your local automotive machine shop.

The valve guide clearance may be checked by using either of the following methods:

  1. Using a micrometer and a telescoping hole gauge, measure the clearance between each valve guide and the valve stem.
    1. Measure the valve stem diameter at top, center and bottom; determine the highest reading.
    2.  
    3. Using the hole gauge, measure the bore of the valve guide at the center.
    4.  
    5. Subtract the highest stem diameter from the guide bore and check to see if the stem-to-guide clearance is within specifications.
    6.  

  2.  
  3. Using a dial micrometer with the valve installed in its normal closed position in the head, move the valve stem back-and-forth parallel with the position of the rocker arm. If the tip deflects more than 0.19mm, the stem-to-guide clearance is excessive.
  4.  

 
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