This is a multi-part message in MIME format.
--===============2420941592365998921==
boundary="----=_NextPart_000_0076_01D092DB.A74ABA90"
This is a multi-part message in MIME format.
------=_NextPart_000_0076_01D092DB.A74ABA90
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
As far as I have seen when adjusting valves any valve is at peak lift at =
only one point on the cam. The tip of the lobe is rounded, so as it =
passes under the flat tappet it is only when the centre of the lobe is =
under the centre of the follower that you will have peak lift. Very =
nearly peak lift a few degrees either side of that, but not much.
You mention comparing valves 1 and 8, but talk about inlet and exhaust. =
It's true that inlet and exhaust lobes are not 180 degrees apart - the =
lobe of an inlet is 16 degrees away from the heel of an exhaust and =
vice-versa, but 1 and 8 are both exhaust valves. And because those =
valves are on cylinders 1 and 4 which fire one complete engine =
revolution apart it wouldn't surprise me if their lobes and heels *are* =
180 degrees apart, which is probably why someone came up with the Rule =
of Nine. All the pairs in the Rule of Nine are the same valve - inlet =
or exhaust - and all on 'opposite' halves of the engine.
But all this is getting into the realm of how many angels can dance on =
the head of a pin. The fact remains that in theory there is a =
significant range of cam rotation where the clearance should be at a =
maximum, meaning that it shouldn't be critical to get the opposite valve =
exactly on the peak of its lobe. But in practice, on a cam by cam =
basis, that doesn't seem to be the case and one needs to check where the =
point of maximum gap is on any valve, and see how that compares with the =
point of maximum lift on its partner valve. As I've said a couple of =
times on engines I've checked the two don't always occur at the same =
time on various valves. It's also the case that the period of maximum =
gap has been surprisingly narrow, like the period of maximum lift, =
whereas on drawings of various cam profiles the base circle i.e. where =
the clearance should be maximum occupies more than 180 degrees.
PaulH.
----- Original Message -----=20
... does the TL of valve 8 mean that you have found the BL of valve 1? =
If I remember correctly, they aren't 180 opposite, input being before or =
after exhaust by some degrees. Is the difference of opposition so =
insignificant that it doesn't matter?
------=_NextPart_000_0076_01D092DB.A74ABA90
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML xmlns=3D"http://www.w3.org/TR/REC-html40"; xmlns:v =3D=20
"urn:schemas-microsoft-com:vml" xmlns:o =3D=20
"urn:schemas-microsoft-com:office:office" xmlns:w =3D=20
"urn:schemas-microsoft-com:office:word" xmlns:m =3D=20
"http://schemas.microsoft.com/office/2004/12/omml";><HEAD>
<META content=3D"text/html; charset=3Diso-8859-1" =
http-equiv=3DContent-Type>
<META name=3DGENERATOR content=3D"MSHTML 8.00.6001.23588">
<STYLE>@font-face {
font-family: Cambria Math;
}
@font-face {
font-family: Calibri;
}
@page WordSection1 {size: 8.5in 11.0in; margin: 1.0in 1.0in 1.0in 1.0in; =
}
P.MsoNormal {
MARGIN: 0in 0in 0pt; FONT-FAMILY: "Calibri",sans-serif; FONT-SIZE: 11pt
}
LI.MsoNormal {
MARGIN: 0in 0in 0pt; FONT-FAMILY: "Calibri",sans-serif; FONT-SIZE: 11pt
}
DIV.MsoNormal {
MARGIN: 0in 0in 0pt; FONT-FAMILY: "Calibri",sans-serif; FONT-SIZE: 11pt
}
A:link {
COLOR: #0563c1; TEXT-DECORATION: underline; mso-style-priority: 99
}
SPAN.MsoHyperlink {
COLOR: #0563c1; TEXT-DECORATION: underline; mso-style-priority: 99
}
A:visited {
COLOR: #954f72; TEXT-DECORATION: underline; mso-style-priority: 99
}
SPAN.MsoHyperlinkFollowed {
COLOR: #954f72; TEXT-DECORATION: underline; mso-style-priority: 99
}
SPAN.EmailStyle17 {
FONT-FAMILY: "Calibri",sans-serif; COLOR: windowtext; mso-style-type: =
personal
}
SPAN.EmailStyle18 {
FONT-FAMILY: "Calibri",sans-serif; COLOR: #1f497d; mso-style-type: =
personal
}
SPAN.EmailStyle19 {
FONT-FAMILY: "Calibri",sans-serif; COLOR: #1f497d; mso-style-type: =
personal-reply
}
.MsoChpDefault {
FONT-SIZE: 10pt; mso-style-type: export-only
}
DIV.WordSection1 {
page: WordSection1
}
</STYLE>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext=3D"edit" spidmax=3D"1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext=3D"edit">
<o:idmap v:ext=3D"edit" data=3D"1" />
</o:shapelayout></xml><![endif]--></HEAD>
<BODY lang=3DEN-US link=3D#0563c1 bgColor=3Dwhite vLink=3D#954f72>
<DIV><FONT size=3D2>As far as I have seen when adjusting valves any =
valve is at=20
peak lift at only one point on the cam. The tip of the lobe is =
rounded, so=20
as it passes under the flat tappet it is only when the centre of the =
lobe is=20
under the centre of the follower that you will have peak lift. =
Very nearly=20
peak lift a few degrees either side of that, but not much.</FONT></DIV>
<DIV><FONT size=3D2></FONT> </DIV>
<DIV><FONT size=3D2>You mention comparing valves 1 and 8, but talk about =
inlet and=20
exhaust. It's true that inlet and exhaust lobes are not 180 =
degrees apart=20
- the lobe of an inlet is 16 degrees away from the heel of an exhaust =
and=20
vice-versa, but 1 and 8 are both exhaust valves. And because =
those=20
valves are on cylinders 1 and 4 which fire one complete engine =
revolution=20
apart it wouldn't surprise me if their lobes and heels *are* 180 =
degrees=20
apart, which is probably why someone came up with the Rule of =
Nine. All=20
the pairs in the Rule of Nine are the same valve - inlet or exhaust - =
and all=20
on 'opposite' halves of the engine.</FONT></DIV>
<DIV><FONT size=3D2></FONT> </DIV>
<DIV><FONT size=3D2>But all this is getting into the realm of how many =
angels can=20
dance on the head of a pin. The fact remains that in theory there =
is a=20
significant range of cam rotation where the clearance should be at =
a=20
maximum, meaning that it shouldn't be critical to get the opposite valve =
exactly=20
on the peak of its lobe. But in practice, on a cam by cam basis, =
that=20
doesn't seem to be the case and one needs to check where the point of =
maximum=20
gap is on any valve, and see how that compares with the point of maximum =
lift on=20
its partner valve. As I've said a couple of times on engines I've =
checked=20
the two don't always occur at the same time on various valves. =
It's also=20
the case that the period of maximum gap has been surprisingly narrow, =
like the=20
period of maximum lift, whereas on drawings of various cam profiles the =
base=20
circle i.e. where the clearance should be maximum occupies more =
than 180=20
degrees.</FONT></DIV>
<DIV><FONT size=3D2></FONT> </DIV>
<DIV><FONT size=3D2>PaulH.</FONT></DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; =
PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV style=3D"FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: =
black"><SPAN=20
style=3D"COLOR: #1f497d">... does the TL of valve 8 mean that you =
have=20
found the BL of valve 1? If I remember correctly, they aren=92t 180 =
opposite,=20
input being before or after exhaust by some degrees. Is the difference =
of=20
opposition so insignificant that it doesn=92t=20
matter?</SPAN></DIV></BLOCKQUOTE></BODY></HTML>
------=_NextPart_000_0076_01D092DB.A74ABA90--
--===============2420941592365998921==
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
_______________________________________________
Mgs@autox.team.net
Archive: http://www.team.net/archive
Unsubscribe: http://autox.team.net/mailman/options/mgs/mharc@autox.team.net
--===============2420941592365998921==--
|