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Thread: Exhaust Valves

  1. 09-23-2013, 04:00 PM #1
    Red Car
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    Exhaust Valves

    Did Porsche change the diameter for exhaust valves between 65 and 68? I'm building an engine for my 65 using late 64 heads. The exhaust valves measure 35mm across the face, Ok per spec. I have a nicer set from a set of 68 heads that measure 37.4mm across the face. The ports in both sets of heads are the same diameter. The 68 valves are noticeably thicker at the edge. I'm not sure they're Ok to use. Any suggestions? Thanks - Mark
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  2. 09-23-2013, 04:27 PM #2
    edmayo
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    The ports aren't the problem, it's the valve seat diameter. Take a pair of dividers and set them to the width of the seat on the valve outer edge, then set the dividers on the seat in the head. The dividers will probably sit on the valve seat outside the 45 degree face. Now try the same thing on your 35 valve, I'll bet the dividers will fall right on the 45 degree seat, if so you have your answer.
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