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VALVE STEM INSTALLED HEIGHT. CBC AUTOMOTIVE TECHNOLOGY. INSTALLING VALVES IN THE HEAD. Inspect Valve spring seats Install positive valve guide seals Prelubricate valve guides. CHECKING VALVE STEM INSTALLED HEIGHT. Valves will sink into head after valve job
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VALVE STEM INSTALLED HEIGHT CBC AUTOMOTIVE TECHNOLOGY
INSTALLING VALVES IN THE HEAD Inspect Valve spring seats Install positive valve guide seals Prelubricate valve guides
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 13-2
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.
DEPTH MICROMETER OR VERNIER CALIPER • Measure with Valve spring removed • Measure spring seat to upper end of installed valve. 17-1
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 17-2
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.
RESULTS OF INSTALLED HEIGHT CHANGE • SEATS SINK INTO HEAD AND CHANGE SPRING LENGTH AND PRESSURE • LACK OF PRESSURE WILL RESULT IN BURNED VALVES
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 17-6
METHODS TO CHECK SPRING INSTALLED HEIGHT 17-5A 17-5B
THAT’S ALL FOLKS ! By Jim Haun