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valve stem clearance

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  • valve stem clearance

    I am in the process of reassembling my '46 heads. The only service manual that I have is a factory reprint. The specs are .004"-.006". I am running Rowe cast iron guides and Rowe black valves. Should I go with the factory specs? Any help would be greatly appreciated.

  • #2
    When using the combo you are installing, I fit the intakes at .0015-.002 and the exhaust at .0025-.003. I ream to within .001 of my fit and finish with a Sunnen valve guide hone. With a stock or mild cam and correct installed height, the valve to guide clearance will hold the spec for at least 100,000 miles.

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    • #3
      If anyone ever got 100,000 out of those Rowe valves I would be very impressed. I would use Manley or plain automotive Stainless over the Rowe Black any day. I always go to the loose side of the spec cause it is too easy to hang a valve by trying to fit to the tightest clearance.

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      • #4
        A riding partner of mine has a 47FL he pretty much lives on. After I first built the motor from parts, it went 80,000 before we took it apart to freshen it up. I still have the valves we took out and aside from some serious pitting in the exhaust valve faces, the Rowe valves showed very little wear. We replaced the valves, shafts and bearings. The motor now has an additional 125,000 miles and still runs strong. About 40,000 miles or so ago, he broke a cylinder and both cylinders were replaced with FHP product. the heads were left alone. The Rowe guides now have over 200,000 on them. Believe it or not.

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        • #5
          I'm sold on Rowe myself. I also use the same specs used by Koanes, which is what Rowe prescribed when I asked them. The majority of todays automotive stainless valve are manufactured in Argentina including Manley, Rowe is 100% USA

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