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Thread: Race length valves

  1. #1
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    Race length valves

    What is the purpose of the so called "race length valves" on twincams and BDAs, which are about 1.5-2mm longer than standard? It seems the groove for the collet sits about the same height than standard. Is it just to have lower height/lighter shims?

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    Re: Race length valves

    You use the std length valves with std shims (biscuit type) for std BDA (RS1600, small valves) engines.
    The race length valves are used with biscuit type shims and buckets with integral stem for tuned engines. Here you can use bigger/hotter cams with more lift and smaller base-circle. The extra length keeps the thickness of the shims lower as you say.
    The BDT engines use valves with a so called long-dick, these are used with buckets without stem.
    See Burton catalogue (online) for differences.

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