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I did the measurements as described in paragraph A to quickly and
inaccurately estimate what lift camshaft could be purchased since there was
no timely ability to make measurements with an assembled long block. I had
either forgotten or discounted the maximum lobe height occurrence before
piston TDC. Time constraints compelled a decision to purchase a
0.447/0.447 lift Comp Cams camshaft from Summit to safely stay within the
clearance limits of the stock 260. From what I've read this camshaft is a
significant improvement over the stock Ford 260 cam toward producing low
end torque without venturing into the compromised driveability of a more
aggressive grind.
Thank you for everyone's advice and grind numbers that provided information
assuring a clearance problem won't occur.
Rob
Rob Hogan
On Mon, Apr 25, 2016 at 8:51 PM, Tom Witt via Tigers <tigers@autox.team.net=
>
wrote:
> *>>>Even with the original 1.67" intake valves, a 0.010 deck height and a
> 0.040 thick head gasket, I don't comprehend where a 0.070" minimum valve =
to
> piston clearance is possible.<<<*
>
> I don=E2=80=99t know to what extent you are versed in the engine, but I=
=E2=80=99ll put
> this out there and use as you see needed (no insult to your knowledge
> intended in my comments).
>
> The valves are recessed in the combustion chamber so the total of the dec=
k
> height and the gasket in and of themselves do not determine the piston to
> valve clearance (if in fact that is what you assumed???). Probably the be=
st
> way to determine the actual clearance is to:
>
> A. If the head is not installed remove a larger intake valve spring. Set
> the head on a flat surface with the valve down, then set and zero a dial
> indicator on the valve stem tip. Push the valve up and measure the
> distance. Add the stated deck and gasket thickness and that gives you t=
he
> clearance. Unless you check them all there is a likelihood that not all
> will be the same. Casting accuracy and seat recession from wear or prior
> valve jobs can change the numbers. But, hopefully the others will be
> =E2=80=9Cclose.=E2=80=9D
>
> B. If the head is installed you can bring the piston to TDC, remove the
> valve spring and do similar. There is the likelihood that carbon build-u=
p
> will give a lower number (but is the actual functional clearance). Also d=
o
> not add in the deck height or the gasket thickness as they are already
> present. DO NOT crank the engine while doing this or you can drop or bend=
a
> valve. A narrow magnet may be required to pull the valve back up. Narrow
> rope can be fed into the chamber through the spark plug hole to support t=
he
> valve while the spring is reinstalled.
>
> Remember this gives you the total distance until a valve hits a piston so
> the required clearance (0.070?) will have to be subtracted from the total
> number. Also, Cams ramp up and down the lobe and may not be at its highe=
st
> lift when the piston is at TDC. Therefore it is possible that the cam li=
ft
> can be greater than the minimal clearance because the piston is not at TD=
C
> (or near enough) when it occurs.
>
> People have used talc powder on clay on top of the piston then cycled
> the engine through a few revolutions, and measured (Calipers) the height =
of
> the clay. Thus getting an =E2=80=9Cactive=E2=80=9D rather than a theoreti=
cal valve
> clearance. This requires assembly/unassembly to measure and a very light
> spring so as not to collapse the lifter (if hydraulic). Also consider tha=
t
> advancing/retarding the cam from the centerline will also alter these
> =E2=80=9Cactive=E2=80=9D clearances. Lastly, the valve stem to rocker tip=
clearance
> (mechanical lifter =E2=80=93 if used) will create additional clearance.
>
> I hope there is something you can glean from this and I haven=E2=80=99t c=
reated
> any confusion.
>
> *From:* Rob Hogan via Tigers <tigers@autox.team.net>
> *Sent:* Friday, April 22, 2016 9:17 PM
> *To:* Tiger's List <tigers@autox.team.net>
> *Subject:* [Tigers] Stock 260 Engine Maximum Cam Lift
>
> Does anyone have experience using a hydraulic lifter camshaft with a lift
> greater than 0.440 (Clymer book page 41 maximum) in the flat top piston
> stock 260 cu. in. engine?
>
> Even with the original 1.67" intake valves, a 0.010 deck height and a
> 0.040 thick head gasket, I don't comprehend where a 0.070" minimum valve =
to
> piston clearance is possible.
>
> Rob Hogan
>
> _______________________________________________
>
> tigers@autox.team.net
>
> Donate: http://www.team.net/donate.html
> Archive: http://www.team.net/archive
> Forums: http://www.team.net/forums
> Unsubscribe:
> http://autox.team.net/mailman/options/tigers/robertdhogan@gmail.com
>
>
>
>
--94eb2c040eec2507d90531653042
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-family:verdana,=
sans-serif">I did the measurements as described in paragraph A to quickly a=
nd inaccurately estimate what lift camshaft could be purchased since there =
was no timely ability to make measurements with an assembled long block.=C2=
=A0 I had either forgotten or discounted the maximum lobe height occurrence=
before piston TDC.=C2=A0 Time constraints compelled a decision to purchase=
a 0.447/0.447 lift Comp Cams camshaft from Summit to safely stay within th=
e clearance limits of the stock 260.=C2=A0 From what I've read this cam=
shaft is a significant improvement over the stock Ford 260 cam toward produ=
cing low end torque without venturing into the compromised driveability of =
a more aggressive grind.</div><div class=3D"gmail_default" style=3D"font-fa=
mily:verdana,sans-serif"><br></div><div class=3D"gmail_default" style=3D"fo=
nt-family:verdana,sans-serif">Thank you for everyone's advice and grind=
numbers that provided information assuring a clearance problem won't o=
ccur.</div><div class=3D"gmail_default" style=3D"font-family:verdana,sans-s=
erif"><br></div><div class=3D"gmail_default" style=3D"font-family:verdana,s=
ans-serif">Rob</div></div><div class=3D"gmail_extra"><br clear=3D"all"><div=
><div class=3D"gmail_signature"><div dir=3D"ltr">Rob Hogan<br></div></div><=
/div>
<br><div class=3D"gmail_quote">On Mon, Apr 25, 2016 at 8:51 PM, Tom Witt vi=
a Tigers <span dir=3D"ltr"><<a href=3D"mailto:tigers@autox.team.net"; tar=
get=3D"_blank">tigers@autox.team.net</a>></span> wrote:<br><blockquote c=
lass=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;=
padding-left:1ex">
<div dir=3D"ltr">
<div dir=3D"ltr">
<div style=3D"FONT-SIZE:12pt;FONT-FAMILY:'Calibri';COLOR:#000000"><=
span class=3D"">
<div><font face=3D"Verdana"><font style=3D"FONT-SIZE:18pt"><em>>>>=
Even with=20
the original 1.67" intake valves, a 0.010 deck height and a 0.040 thic=
k head=20
gasket, I don't comprehend where a 0.070" minimum valve to piston =
clearance is=20
possible.<<<</em></font></font></div>
<div>=C2=A0</div>
</span><div>I don=E2=80=99t know to what extent you are versed in the engin=
e, but I=E2=80=99ll put this=20
out there and use as you see needed (no insult to your knowledge intended i=
n my=20
comments).</div>
<div>=C2=A0</div>
<div>The valves are recessed in the combustion chamber so the total of the =
deck=20
height and the gasket in and of themselves do not determine the piston to v=
alve=20
clearance (if in fact that is what you assumed???). Probably the best way t=
o=20
determine the actual clearance is to:</div>
<div>=C2=A0</div>
<div>A. If the head is not installed remove a larger intake valve spring. S=
et=20
the head on a flat surface with the valve down, then set and zero a dial=20
indicator on the valve stem tip. Push the valve up and measure the=20
distance.=C2=A0=C2=A0 Add the stated deck and gasket thickness and that giv=
es=20
you the clearance. Unless you check them all there is a likelihood that not=
all=20
will be the same. Casting accuracy and seat recession from wear or prior va=
lve=20
jobs can change the numbers. But, hopefully the others will be =E2=80=9Cclo=
se.=E2=80=9D</div>
<div>=C2=A0</div>
<div>B. If the head is installed you can bring the piston to TDC, remove th=
e=20
valve spring and do similar.=C2=A0 There is the likelihood that carbon buil=
d-up=20
will give a lower number (but is the actual functional clearance). Also do =
not=20
add in the deck height or the gasket thickness as they are already present.=
DO=20
NOT crank the engine while doing this or you can drop or bend a valve. A na=
rrow=20
magnet may be required to pull the valve back up. Narrow rope can be fed in=
to=20
the chamber through the spark plug hole to support the valve while the spri=
ng is=20
reinstalled. </div>
<div>=C2=A0</div>
<div>Remember this gives you the total distance until a valve hits a piston=
so=20
the required clearance (0.070?) will have to be subtracted from the total=
=20
number.=C2=A0 Also, Cams ramp up and down the lobe and may not be at its hi=
ghest=20
lift when the piston is at TDC.=C2=A0 Therefore it is possible that the cam=
lift=20
can be greater than the minimal clearance because the piston is not at TDC =
(or=20
near enough) when it occurs.</div>
<div>=C2=A0</div>
<div>=C2=A0 People have used talc powder on clay on top of the piston then=
=20
cycled the engine through a few revolutions, and measured (Calipers) the he=
ight=20
of the clay. Thus getting an =E2=80=9Cactive=E2=80=9D rather than a theoret=
ical valve=20
clearance.=C2=A0 This requires assembly/unassembly to measure and a very li=
ght=20
spring so as not to collapse the lifter (if hydraulic). Also consider that=
=20
advancing/retarding the cam from the centerline will also alter these =E2=
=80=9Cactive=E2=80=9D=20
clearances. Lastly, the valve stem to rocker tip clearance (mechanical lift=
er =E2=80=93=20
if used) will create additional clearance.</div>
<div>=C2=A0</div>
<div>I hope there is something you can glean from this and I haven=E2=80=99=
t created any=20
confusion. </div>
<div style=3D"FONT-SIZE:small;TEXT-DECORATION:none;FONT-FAMILY:"Calibr=
i";FONT-WEIGHT:normal;COLOR:#000000;FONT-STYLE:normal;DISPLAY:inline">
<div style=3D"FONT:10pt tahoma">
<div>=C2=A0</div>
<div style=3D"BACKGROUND:#f5f5f5">
<div><b>From:</b> <a title=3D"tigers@autox.team.net" href=3D"mailto:tigers@=
autox.team.net" target=3D"_blank">Rob Hogan via Tigers</a> </div>
<div><b>Sent:</b> Friday, April 22, 2016 9:17 PM</div>
<div><b>To:</b> <a title=3D"tigers@autox.team.net" href=3D"mailto:tigers@au=
tox.team.net" target=3D"_blank">Tiger's List</a> </div><span class=3D""=
>
<div><b>Subject:</b> [Tigers] Stock 260 Engine Maximum Cam=20
Lift</div></span></div></div>
<div>=C2=A0</div></div><span class=3D"">
<div style=3D"FONT-SIZE:small;TEXT-DECORATION:none;FONT-FAMILY:"Calibr=
i";FONT-WEIGHT:normal;COLOR:#000000;FONT-STYLE:normal;DISPLAY:inline">
<div dir=3D"ltr">
<div class=3D"gmail_default" style=3D"FONT-SIZE:large;FONT-FAMILY:verdana,s=
ans-serif">Does anyone have=20
experience using a hydraulic lifter camshaft with a lift greater than 0.440=
=20
(Clymer book page 41 maximum) in the flat top piston stock 260 cu. in.=20
engine?</div>
<div class=3D"gmail_default" style=3D"FONT-SIZE:large;FONT-FAMILY:verdana,s=
ans-serif">=C2=A0</div>
<div class=3D"gmail_default" style=3D"FONT-SIZE:large;FONT-FAMILY:verdana,s=
ans-serif">Even with the original=20
1.67" intake valves, a 0.010 deck height and a 0.040 thick head gasket=
, I don't=20
comprehend where a 0.070" minimum valve to piston clearance is possibl=
e.</div>
<div class=3D"gmail_default" style=3D"FONT-SIZE:large;FONT-FAMILY:verdana,s=
ans-serif">=C2=A0</div>
<div class=3D"gmail_default" style=3D"FONT-SIZE:large;FONT-FAMILY:verdana,s=
ans-serif"> </div>
<div>
<div>
<div dir=3D"ltr">Rob=20
Hogan<br></div></div></div></div></div></span></div></div></div>
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<br>
<br>
<br></blockquote></div><br></div>
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