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Yes Bob That is correct.
Usually the rear is about about 0.001" higher than the front.
With flat tappets the center of the tappet is usually also about 0.001"
higher than the edges.
M
On Mon, May 11, 2020 at 10:40 AM Bob Spidell <bspidell@comcast.net> wrote:
> 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>
> wrote:
>
>> 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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Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-family:comic sa=
ns ms,sans-serif;font-size:small">Yes Bob That is correct. <br></div><div c=
lass=3D"gmail_default" style=3D"font-family:comic sans ms,sans-serif;font-s=
ize:small">Usually the rear is about about 0.001" higher than the fron=
t.</div><div class=3D"gmail_default" style=3D"font-family:comic sans ms,san=
s-serif;font-size:small">With flat tappets the center of the tappet is usua=
lly also about 0.001" higher than the edges.</div><div class=3D"gmail_=
default" style=3D"font-family:comic sans ms,sans-serif;font-size:small"><br=
></div><div class=3D"gmail_default" style=3D"font-family:comic sans ms,sans=
-serif;font-size:small">M<br></div></div><br><div class=3D"gmail_quote"><di=
v dir=3D"ltr" class=3D"gmail_attr">On Mon, May 11, 2020 at 10:40 AM Bob Spi=
dell <<a href=3D"mailto:bspidell@comcast.net";>bspidell@comcast.net</a>&g=
t; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0p=
x 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
=20
=20
=20
<div>
Aren't the cam lobes slightly sloped from edge-to-edge as well?<br>
<br>
<br>
<div>On 5/11/2020 4:50 AM, Michael Salter
wrote:<br>
</div>
<blockquote type=3D"cite">
=20
<div dir=3D"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.=C2=A0
<div dir=3D"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.=C2=A0</div>
<div dir=3D"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=3D"auto">Regarding the idea that the engine has to be
turning at 1500 RPM to throw oil up to the cam I totally
disagree=C2=A0with that.=C2=A0</div>
<div dir=3D"auto">Even 600 RPM is 10 rotations a second ....=C2=A0
hmmmm.</div>
<div dir=3D"auto"><br>
</div>
<div dir=3D"auto">M</div>
</div>
<br>
<div class=3D"gmail_quote">
<div dir=3D"ltr" class=3D"gmail_attr">On Sun, May 10, 2020, 7:25 PM
richard mayor, <<a href=3D"mailto:boyracer466@gmail.com"; targe=
t=3D"_blank">boyracer466@gmail.com</a>> wrote:<br>
</div>
<blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex=
;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir=3D"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.=C2=
=A0
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></pre>
</blockquote>
<br>
</div>
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