Pontiac Fiero 1984-1988 Repair Guide

Valves

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REMOVAL & INSPECTION





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Fig. Fig. 1 Use a suitable tool to compress the valve springs



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Fig. Fig. 2 Typical wear points on a common valve



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Fig. Fig. 3 Inspect the valve tips to ensure proper valve rotator operation



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Fig. Fig. 4 Use a valve spring compressor to relieve spring tension and a small magnet to remove the valve keepers



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Fig. Fig. 5 Remove the valve cap from the spring...



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Fig. Fig. 6 ... then remove the valve shield from the spring



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Fig. Fig. 7 Invert the cylinder head and withdraw the valve from the cylinder head bore



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Fig. Fig. 8 A dial gauge may be used to check valve stem-to-guide clearance



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Fig. Fig. 9 Use a micrometer to check the valve stem diameter

  1. Remove the cylinder head(s) from the vehicle as previously outlined in the Cylinder Head removal and installation procedures.
  2.  
  3. Using a suitable valve spring compressor, compress the valve spring and remove the valve keys using a magnetic retrieval tool.
  4.  
  5. Slowly release the compressor and remove the valve spring caps (or rotors) and the valve springs.
  6.  


CAUTION
The valve springs are under high spring load, always wear safety glasses when removing valve springs. Decompressing a valve spring quickly may cause personal injury.

  1. Fabricate a valve arrangement board (piece of cardboard with holes punched through) to use when you remove the valves, which will indicate the port in which each valve was originally installed (and which cylinder head on V6 models). Also note that the valve keys, rotators, caps, etc. should be arranged in a manner which will allow you to install them on the valve on which they were originally removed.
  2.  
  3. Remove and discard the valve seals. On models using the umbrella type seals, note the location of the large and small seals for assembly purposes.
  4.  
  5. Thoroughly clean the valves on the wire wheel of a bench grinder, then clean the cylinder head mating surface with a soft wire wheel, a soft wire brush, or a wooden scraper. Avoid using a metallic scraper, since this can cause damage to the cylinder head mating surface, especially on models with aluminum heads.
  6.  
  7. Using a valve guide cleaner chucked into a drill, clean all of the valve guides.
  8.  
  9. Install each valve into its respective port (guide) of the cylinder head.
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  11. Mount a dial indicator so that the stem is at 90° to the valve stem, as close to the valve guide as possible.
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  13. Move the valve off its seat, and measure the valve guide-to-stem clearance by rocking the stem back and forth to actuate the dial indicator.
  14.  
  15. Measure the valve stems using a micrometer, and compare to specifications, to determine whether stem or guide wear is responsible for excessive clearance. Consult the machine shop for valve guide reconditioning .
  16.  

Consult the Specifications tables earlier in this Section.

REFACING



Using a valve grinder, resurface the valves according to specifications in this section.

All machine work should be performed by a competent, professional machine shop.


CAUTION
Valve face angle is not always identical to valve seat angle.

A minimum margin of 1 / 32 inch should remain after grinding the valve. The valve stem top should also be squared and resurfaced, by placing the stem in the V-block of the grinder, and turning it while pressing lightly against the grinding wheel. Be sure to chamfer the edge of the tip so that the squared edges don't dig into the rocker arm.

LAPPING



This procedure should be performed after the valves and seats have been machined, to insure that each valve mates to each seat precisely.

  1. Invert the cylinder head, lightly lubricate the valve stems, and install the valves in the head as numbered.
  2.  
  3. Coat valve seats with fine grinding compound, and attach the lapping tool suction cup to a valve head.
  4.  

Moisten the suction cup.

  1. Rotate the tool between your palms, changing position and lifting the tool often to prevent grooving.
  2.  
  3. Lap the valve until a smooth and uniform wear pattern exists.
  4.  
  5. Remove the valve and tool, and rinse away all traces of grinding compound.
  6.  

 
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