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Re: [Healeys] Oil Pressure

To: healeys@autox.team.net
Subject: Re: [Healeys] Oil Pressure
From: Bob Spidell <bspidell@comcast.net>
Date: Mon, 11 May 2020 07:32:03 -0700
Delivered-to: mharc@autox.team.net
Delivered-to: healeys@autox.team.net
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Aren't the cam lobes slightly sloped from edge-to-edge as well?


On 5/11/2020 4:50 AM, Michael Salter wrote:
> Richard is,as usual, absolutely correct in that the lifters are very 
> slightly convex on the base however it is not that which makes them 
> rotate rather that the fact that the lifter bores are slightly 
> displaced from the centerline on the cam lobes.
> In many Healey engines that I have disassembled however it is quite 
> apparent that at least some of the lifters have not been rotating as 
> evidenced by the rectangular shape of the witness mark on the base. By 
> measuring the position of the rectangle one can confirm that the 
> displacement is about 1mm as I recall.
> I've never been able to determine why some lifters fail to rotate as 
> they seen quite free in the bore.
> Regarding the idea that the engine has to be turning at 1500 RPM to 
> throw oil up to the cam I totally disagree with that.
> Even 600 RPM is 10 rotations a second .... hmmmm.
>
> M
>
> On Sun, May 10, 2020, 7:25 PM richard mayor, <boyracer466@gmail.com 
>
>     The lifter faces are not flat. They have a crown so they rotate in
>     the bores as the cam lobes move across them. At low RPMs the
>     lifters do not rotate so much. It is absolutely essential on
>     initial start up that the lifters are rotating so the cam and
>     lifters can properly bed in. This is accomplished if the engine is
>     reving at least 1500 RPM.
>


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    Aren't the cam lobes slightly sloped from edge-to-edge as well?<br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 5/11/2020 4:50 AM, Michael Salter
      wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAB3i7LJnNnR5xwrkMYHjgbU=UWAXXKswsSscfUe3sywK3tePjA@mail.gmail.com">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div dir="auto">Richard is,as usual, absolutely correct in that
        the lifters are very slightly convex on the base however it is
        not that which makes them rotate rather that the fact that the
        lifter bores are slightly displaced from the centerline on the
        cam lobes. 
        <div dir="auto">In many Healey engines that I have disassembled
          however it is quite apparent that at least some of the lifters
          have not been rotating as evidenced by the rectangular shape
          of the witness mark on the base. By measuring the position of
          the rectangle one can confirm that the displacement is about
          1mm as I recall. </div>
        <div dir="auto">I've never been able to determine why some
          lifters fail to rotate as they seen quite free in the bore.</div>
        <div dir="auto">Regarding the idea that the engine has to be
          turning at 1500 RPM to throw oil up to the cam I totally
          disagree with that. </div>
        <div dir="auto">Even 600 RPM is 10 rotations a second .... 
          hmmmm.</div>
        <div dir="auto"><br>
        </div>
        <div dir="auto">M</div>
      </div>
      <br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">On Sun, May 10, 2020, 7:25 PM
          richard mayor, &lt;<a href="mailto:boyracer466@gmail.com";
            moz-do-not-send="true">boyracer466@gmail.com</a>&gt; wrote:<br>
        </div>
        <blockquote class="gmail_quote" style="margin:0 0 0
          .8ex;border-left:1px #ccc solid;padding-left:1ex">
          <div dir="ltr">The lifter faces are not flat. They have a
            crown so they rotate in the bores as the cam lobes move
            across them. At low RPMs the lifters do not rotate so much. 
            It is absolutely essential on initial start up that the
            lifters are rotating so the cam and lifters can properly bed
            in. This is accomplished if the engine is reving at least
            1500 RPM.<br>
          </div>
          <br>
        </blockquote>
      </div>
      <pre class="moz-quote-pre" wrap="">
</pre>
    </blockquote>
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