Subject: [Fot] Exhaust Valve Shape: room for improvement?

From: Phil Gott via Fot <[email-masked]>
Date: Tue, 6 Oct 2020 08:45:00 -0400

Does anyone know why the 5/16 stem exhaust valve flares out in a cone shape to the valve head instead of maintaining the stem diameter diameter all the way to the head? I am thinking that there could be a gain if we can find a valve of correct dimensions without that flare.
Phil Gott

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From: Duncan Charlton via Fot <[email-masked]>
Date: Tue, 6 Oct 2020 10:33:06 -0500

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I don't have definite engineering knowledge but I suspect there is more
than one reason for this.  Increasing the mass of the valve head near the
transition to the stem may have to do with heat transfer and resistance to
distortion, but I suspect the exiting flow of exhaust gas may determine the
shape as well.

You could reduce the overall mass by using smaller-diameter stems.

Duncan

On Tue, Oct 6, 2020 at 7:52 AM Phil Gott via Fot <[email-masked]> wrote:

> Does anyone know why the 5/16 stem exhaust valve flares out in a cone
> shape to the valve head instead of maintaining the stem diameter diameter
> all the way to the head? I am thinking that there could be a gain if we can
> find a valve of correct dimensions without that flare.
> Phil Gott
>
>
>
> Sent from my iPhone
> Unsubscribe/Manage <http://www.team.net/pipermail/fotUnsubscribe/Manage>:
> http://autox.team.net/mailman/options/fot/[email-masked]
>
>
>

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<div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-family:garamond=
,serif;font-size:large">I don&#39;t have definite engineering knowledge but=
 I suspect there is more than one reason for this.=C2=A0 Increasing the mas=
s of the valve head near the transition to the stem may have to do with hea=
t transfer and resistance to distortion, but I suspect the exiting=C2=A0flo=
w of exhaust gas may determine the shape as well.=C2=A0=C2=A0</div><div cla=
ss=3D"gmail_default" style=3D"font-family:garamond,serif;font-size:large"><=
br></div><div class=3D"gmail_default" style=3D"font-family:garamond,serif;f=
ont-size:large">You could reduce the overall mass by using smaller-diameter=
 stems.</div><div class=3D"gmail_default" style=3D"font-family:garamond,ser=
if;font-size:large"><br></div><div class=3D"gmail_default" style=3D"font-fa=
mily:garamond,serif;font-size:large">Duncan</div></div><br><div class=3D"gm=
ail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Tue, Oct 6, 2020 at 7:5=
2 AM Phil Gott via Fot &lt;<a href=3D"mailto:[email-masked]">fot@autox.=
team.net</a>&gt; 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-le=
ft:1ex">Does anyone know why the 5/16 stem exhaust valve flares out in a co=
ne shape to the valve head instead of maintaining the stem diameter diamete=
r all the way to the head? I am thinking that there could be a gain if we c=
an find a valve of correct dimensions without that flare.<br>
Phil Gott<br>
<br>
<br>
<br>
Sent from my iPhone<br>
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