VALVE STEM INSTALLED HEIGHT

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VALVE STEM INSTALLED HEIGHT

• CBC AUTOMOTIVE TECHNOLOGY

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INSTALLING VALVES IN THE HEAD

• Inspect Valve spring seats
• Install positive valve guide seals
• Prelubricate valve guides

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CHECKING VALVE STEM INSTALLED HEIGHT

• Valves will sink into head after valve job
• Additional stem extension will change rocker arm
  geometry
• Stem height can be checked two ways
• Depth Micrometer or Vernier Caliper
• Dial Indicator

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STEM HEIGHT SPECS

• Hard to find specifications
• Measure stem height before doing service work
• Compare reading with a similar reading taken
  after valve and seat work is finished.

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DEPTH MICROMETER OR VERNIER CALIPER

• Measure with Valve spring removed
• Measure spring seat to upper end of installed
  valve.

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CHRYSLER METHOD FOR STEM INSTALLED HEIGHT
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DIAL INDICATOR

• Measures stem height in thousandths of an inch
• Some tools supply original specifications
• Calibrate Tool
• Install gauge over stem and measure stem height

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CORRECTING VAVLE STEM INSTALLED HEIGHT

• Subtract original reading from finished reading
• This amount will be removed from stem end
• Stems usually hardened .030 deep
• Maximum that can be ground is .020
• If more reduction in stem height is needed,
  replace valve seat.

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VALVE SPRING INSTALLED HEIGHT

• Part 2

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RESULTS OF INSTALLED HEIGHT CHANGE

• SEATS SINK INTO HEAD AND CHANGE SPRING LENGTH AND
  PRESSURE
• LACK OF PRESSURE WILL RESULT IN BURNED VALVES

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To Correct Spring Height

• To correct installed height, you must shim spring
• Shims come in three thickness'
• .060 12lbs change
• .030 6 lb change
• .015 3 lb change
• Serration's go next to head

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METHODS TO CHECK SPRING INSTALLED HEIGHT
17-5A
17-5B
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THATS ALL FOLKS !

• By Jim Haun