healeys
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Re: [Healeys] Valve clearances

To: WILLIAM B LAWRENCE <ynotink@msn.com>
Subject: Re: [Healeys] Valve clearances
From: Michael Salter <michael.salter@gmail.com>
Date: Sun, 13 Jan 2019 18:23:17 -0500
Cc: "healeys@autox.team.net" <healeys@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: healeys@autox.team.net
References: <000501d4aa03$63019960$2904cc20$@alexarevel.plus.com> <002a01d4aa32$032cc760$09865620$@com.au> <2f61c142-c37b-c0a6-0f0e-7336fc87a80a@comcast.net> <957498721.310892.1547332796600@mail.yahoo.com> <9c740d58-3ead-a51d-4cfc-0f2f9c56fb3b@comcast.net> <DM6PR07MB453803FB848355453FEFA5A9A5870@DM6PR07MB4538.namprd07.prod.outlook.com>
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This is another subject that I often wonder about.
If the valve clearance is there to ensure that the valves are fully closed
when the engine is hot then why, when I check the clearances on a hot
engine after a dyno run,  are they hardly any less than they were cold?
I can appreciate that the valve train components grow because of the heat
but surely the block and head and rocker shaft pedistals also grow and thus
there is little if any net change.
I also appreciate that the exhaust valve stem get really hot but ????
Just wondering....

M

On Sun, Jan 13, 2019, 6:42 AM WILLIAM B LAWRENCE <ynotink@msn.com wrote:

> I disagree that valve clearances are not critical. As the engine comes up
> to temperature the metal parts of the valve train (valves, lifters, push
> rods, the head itself and the rocker shaft towers) increase in length and
> the valve clearances are calculated to assure that this expansion isn't
> allowed to affect the sealing of the valves on their seats. If the valves
> are set too tight they reach a point where they won't touch the seats and
> therefore won't seal. Hot gases rushing through the gaps will quickly ero=
de
> the valves. Also increasing the duration and/or lift of the cam has the
> effect of the  decreasing the length of the opening and closing ramps on
> the back side of the cam This reduces the length of time (dwell) the valv=
e
> remains on the seat. Increasing the valve clearance restores the dwell ti=
me
> the valve needs to transfer its heat load to the cooling system through t=
he
> valve seat and the cylinder head. Too little dwell time or the lack of
> proper valve sealing are two causes of burned valves.
>
> In my own experience I installed an Isky cam with a grind a little more
> aggressive than the 100M cam and set the clearances to 0.012" per the
> manual. Within about 2,000 miles the exhaust valves were trashed. I then
> took the time to read the Isky installation instructions which specifical=
ly
> state the valve clearance needs to be set to 0.018". I re-installed the
> head with new valves and set them to Isky's spec and never had another
> problem with burned valves.
>
> Follow the cam grinder's recommendations and you will avoid trouble.
>
> Bill Lawrence
> BN1 #554
> ------------------------------
> *From:* Healeys <healeys-bounces@autox.team.net> on behalf of Bob Spidell
> <bspidell@comcast.net>
> *Sent:* Saturday, January 12, 2019 11:10 PM
> *To:* Michael MacLean; healeys@autox.team.net
> *Subject:* Re: [Healeys] Valve clearances
>
>
> I should note the rockers are pretty noisy at 0.015; IIRC I tightened the=
m
> up just a bit.
> On 1/12/2019 2:39 PM, Michael MacLean wrote:
>
> I'd go with .016.  You can always tighten it.  Better loose than tight.
> Mike MacLean
>
> On Saturday, January 12, 2019, 11:01:32 AM PST, Bob Spidell
> <bspidell@comcast.net> <bspidell@comcast.net> wrote:
>
>
> Makes sense (for some reason).  I put a DWR1 cam in my BJ8 which,
> according to DWR, 'is a little better than the BJ8 cam and so works well =
in
> any standard or mildly tuned car' but I think the 0.015" applies to all
> profiles on the spec sheet.
>
> Bob
> On 1/11/2019 8:48 PM, John Rowe wrote:
>
> Simon,
>
> Modified cams require the large clearance (don=E2=80=99t ask me why?) So =
go for
> .015 that is what mine is.
>
> John Rowe
>
> Qld
>
> Australia
>
>
>
> *From:* Healeys [mailto:healeys-bounces@autox.team.net
> <healeys-bounces@autox.team.net>] *On Behalf Of *
> simon.lachlan@alexarevel.plus.com
> *Sent:* Saturday, 12 January 2019 9:14 AM
> *To:* Healeys
> *Subject:* [Healeys] Valve clearances
>
>
>
> The car is a MkII BT7.
>
> The BMC manual says adjust the clearances, cold, to 0.012=E2=80=9D.
>
> Denis Welch said I should go 0.015=E2=80=9D, cold, after fitting their =
=E2=80=9CFast Road=E2=80=9D
> cam.
>
> The rolling road guy said 0.016=E2=80=9D, warm.
>
>
>
> I have the radiator out right now so I can get a nice socket onto that nu=
t
> and have a go at the clearances.
>
> Stick with 0.015=E2=80=9D, cold?
>
>
>
> Thanks,
>
> Simon
>
>
>
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>

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<div dir=3D"auto">This is another subject that I often wonder about.=C2=A0<=
div dir=3D"auto">If the valve clearance is there to ensure that the valves =
are fully closed when the engine is hot then why, when I check the clearanc=
es on a hot engine after a dyno run,=C2=A0 are they hardly any less than th=
ey were cold?</div><div dir=3D"auto">I can appreciate that the valve train =
components grow because of the heat but surely the block and head and rocke=
r shaft pedistals also grow and thus there is little if any net change.</di=
v><div dir=3D"auto">I also appreciate that the exhaust valve stem get reall=
y hot but ????</div><div dir=3D"auto">Just wondering....</div><div dir=3D"a=
uto"><br></div><div dir=3D"auto">M</div></div><br><div class=3D"gmail_quote=
"><div dir=3D"ltr">On Sun, Jan 13, 2019, 6:42 AM WILLIAM B LAWRENCE &lt;<a =
href=3D"mailto:ynotink@msn.com";>ynotink@msn.com</a> wrote:<br></div><blockq=
uote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc =
solid;padding-left:1ex">




<div dir=3D"ltr">
<div style=3D"font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color=
:rgb(0,0,0)">
I disagree that valve clearances are not critical. As the engine comes up t=
o temperature the metal parts of the valve train (valves, lifters, push rod=
s, the head itself and the rocker shaft towers) increase in length and the =
valve clearances are calculated
 to assure that this expansion isn&#39;t allowed to affect the sealing of t=
he valves on their seats. If the valves are set too tight they reach a poin=
t where they won&#39;t touch the seats and therefore won&#39;t seal. Hot ga=
ses rushing through the gaps will quickly erode
 the valves. Also i<span style=3D"font-family:Calibri,Helvetica,sans-serif;=
background-color:rgb(255,255,255);display:inline!important">ncreasing the d=
uration and/or lift of the cam has the effect of the =C2=A0decreasing the l=
ength
 of the opening and closing ramps on the back side of the cam This reduces =
the length of time (dwell) the valve remains on the seat. Increasing the va=
lve clearance restores the dwell time the valve needs to transfer its heat =
load to the cooling system through
 the valve seat and the cylinder head. Too little dwell time or the lack of=
 proper valve sealing are two causes of burned valves.</span></div>
<div style=3D"font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color=
:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color=
:rgb(0,0,0)">
In my own experience I installed an Isky cam with a grind a little more agg=
ressive than the 100M cam and set the clearances to 0.012&quot; per the man=
ual. Within about 2,000 miles the exhaust valves were trashed. I then took =
the time to read the Isky installation
 instructions which specifically state the valve clearance needs to be set =
to 0.018&quot;. I re-installed the head with new valves and set them to Isk=
y&#39;s spec and never had another problem with burned valves.</div>
<div style=3D"font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color=
:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color=
:rgb(0,0,0)">
Follow the cam grinder&#39;s recommendations and you will avoid trouble.</d=
iv>
<div style=3D"font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color=
:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color=
:rgb(0,0,0)">
Bill Lawrence</div>
<div style=3D"font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color=
:rgb(0,0,0)">
BN1 #554</div>
<div id=3D"m_1603937236670712738appendonsend"></div>
<hr style=3D"display:inline-block;width:98%">
<div id=3D"m_1603937236670712738divRplyFwdMsg" dir=3D"ltr"><font face=3D"Ca=
libri, sans-serif" style=3D"font-size:11pt" color=3D"#000000"><b>From:</b> =
Healeys &lt;<a href=3D"mailto:healeys-bounces@autox.team.net"; target=3D"_bl=
ank" rel=3D"noreferrer">healeys-bounces@autox.team.net</a>&gt; on behalf of=
 Bob Spidell &lt;<a href=3D"mailto:bspidell@comcast.net"; target=3D"_blank" =
rel=3D"noreferrer">bspidell@comcast.net</a>&gt;<br>
<b>Sent:</b> Saturday, January 12, 2019 11:10 PM<br>
<b>To:</b> Michael MacLean; <a href=3D"mailto:healeys@autox.team.net"; targe=
t=3D"_blank" rel=3D"noreferrer">healeys@autox.team.net</a><br>
<b>Subject:</b> Re: [Healeys] Valve clearances</font>
<div>=C2=A0</div>
</div>
<div style=3D"background-color:#ffffff">
<p>I should note the rockers are pretty noisy at 0.015; IIRC I tightened th=
em up just a bit.<br>
</p>
<div class=3D"m_1603937236670712738x_moz-cite-prefix">On 1/12/2019 2:39 PM,=
 Michael MacLean wrote:<br>
</div>
<blockquote type=3D"cite">
<div class=3D"m_1603937236670712738x_ydpe1d3e9c5yahoo-style-wrap" style=3D"=
font-family:times new roman,new york,times,serif;font-size:16px">
<div>I&#39;d go with .016.=C2=A0 You can always tighten it.=C2=A0 Better lo=
ose than tight.</div>
<div>Mike MacLean<br>
</div>
<div><br>
</div>
</div>
<div id=3D"m_1603937236670712738x_yahoo_quoted_8268064185" class=3D"m_16039=
37236670712738x_yahoo_quoted">
<div style=3D"font-family:&#39;Helvetica Neue&#39;,Helvetica,Arial,sans-ser=
if;font-size:13px;color:#26282a">
<div>On Saturday, January 12, 2019, 11:01:32 AM PST, Bob Spidell <a class=
=3D"m_1603937236670712738x_moz-txt-link-rfc2396E" href=3D"mailto:bspidell@c=
omcast.net" target=3D"_blank" rel=3D"noreferrer">
&lt;bspidell@comcast.net&gt;</a> wrote: </div>
<div><br>
</div>
<div><br>
</div>
<div>
<div id=3D"m_1603937236670712738x_yiv1110160614">
<div>
<p>Makes sense (for some reason).=C2=A0 I put a DWR1 cam in my BJ8 which, a=
ccording to DWR, &#39;is a little better than the BJ8 cam and so works well=
 in any standard or mildly tuned car&#39; but I think the 0.015&quot; appli=
es to all profiles on the spec sheet.<br clear=3D"none">
</p>
<p>Bob<br clear=3D"none">
</p>
<div class=3D"m_1603937236670712738x_yiv1110160614yqt0287165987" id=3D"m_16=
03937236670712738x_yiv1110160614yqt70378">
<div class=3D"m_1603937236670712738x_yiv1110160614moz-cite-prefix">On 1/11/=
2019 8:48 PM, John Rowe wrote:<br clear=3D"none">
</div>
<blockquote type=3D"cite"></blockquote>
</div>
</div>
<div class=3D"m_1603937236670712738x_yiv1110160614yqt0287165987" id=3D"m_16=
03937236670712738x_yiv1110160614yqt92654">
<div>
<div class=3D"m_1603937236670712738x_yiv1110160614WordSection1">
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span style=3D"c=
olor:#1f497d">Simon,</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span style=3D"c=
olor:#1f497d">Modified cams require the large clearance (don=E2=80=99t ask =
me why?) So go for .015 that is what mine is.</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span style=3D"c=
olor:#1f497d">John Rowe</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span style=3D"c=
olor:#1f497d">Qld</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span style=3D"c=
olor:#1f497d">Australia</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span style=3D"c=
olor:#1f497d">=C2=A0</span></p>
<div>
<div style=3D"border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0cm =
0cm 0cm">
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><b><span lang=3D=
"EN-US" style=3D"font-size:10.0pt">From:</span></b><span lang=3D"EN-US" sty=
le=3D"font-size:10.0pt"> Healeys [<a rel=3D"nofollow noreferrer" shape=3D"r=
ect" class=3D"m_1603937236670712738x_yiv1110160614moz-txt-link-freetext" hr=
ef=3D"mailto:healeys-bounces@autox.team.net"; target=3D"_blank">mailto:heale=
ys-bounces@autox.team.net</a>]
<b>On Behalf Of </b><a rel=3D"nofollow noreferrer" shape=3D"rect" class=3D"=
m_1603937236670712738x_yiv1110160614moz-txt-link-abbreviated" href=3D"mailt=
o:simon.lachlan@alexarevel.plus.com" target=3D"_blank">simon.lachlan@alexar=
evel.plus.com</a><br clear=3D"none">
<b>Sent:</b> Saturday, 12 January 2019 9:14 AM<br clear=3D"none">
<b>To:</b> Healeys<br clear=3D"none">
<b>Subject:</b> [Healeys] Valve clearances</span></p>
</div>
</div>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal">=C2=A0</p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">The car is a MkII BT7.</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">The BMC manual says adjust the clearances, cold, to 0.012=E2=80=9D.</s=
pan></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">Denis Welch said I should go 0.015=E2=80=9D, cold, after fitting their=
 =E2=80=9CFast Road=E2=80=9D cam.</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">The rolling road guy said 0.016=E2=80=9D, warm.</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">=C2=A0</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">I have the radiator out right now so I can get a nice socket onto that=
 nut and have a go at the clearances.</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">Stick with 0.015=E2=80=9D, cold?</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">=C2=A0</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">Thanks,</span></p>
<p class=3D"m_1603937236670712738x_yiv1110160614MsoNormal"><span lang=3D"EN=
-GB">Simon</span></p>
</div>
<br>
</div>
</div>
</div>
</div>
</div>
</div>
<div id=3D"m_1603937236670712738x_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2">
<table style=3D"border-top:1px solid #d3d4de">
<tbody>
<tr>
<td style=3D"width:55px;padding-top:13px"><br>
</td>
<td style=3D"width:470px;padding-top:12px;color:#41424e;font-size:13px;font=
-family:Arial,Helvetica,sans-serif;line-height:18px">
<br>
</td>
</tr>
</tbody>
</table>
</div>
</blockquote>
</div>
</div>

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