DeTomaso Mailing List: February 00, Message #28

I'm not an expert.  This is how I understand it.  The key difference between
cam types hydraulic, solid, hyrdaulic roller and solid roller is the
profile, how fast can the lobe rise and fall.  The idea is the longer a
valve is at maximum lift (where the best air flow is) the better.  Now as I
understand it, a hydraulic (either type) is limited by the oil valves inside
and the oil itself.  While a solid is plain old solid.  An easy way to tell
how aggressive the ramps are is by looking at the strength of the valve
spring.  A faster ramp needs more spring pressure.  The valve is moving the
same distance, about 0.5" but it is getting there quicker, more valve speed,
more valve momentum more spring pressure to keep the lobe on the cam.
Otherwise the lifter jumps and crashes back onto the cam.  Not good.

Example time.  I only have a Comp Cams catalog so I have to use them as a
guide.

Hydraulic flat - spring type is 972 or 924
Hydraulic roller - spring type is 924
Solid flat - spring type 928
Solid roller - spring type  947 or 943.

Spring pressure
972 - 125 closed, 275 open
924 - 125 c, 315 o
928 - 160 c, 370 o
947 - 340c , 835 o
943 - 235c, 635 o

As you can see they sell hydraulic flats that require the same spring as the
roller, but even the solid flats require a stronger spring than the
hydraulic roller.  Now this is a simplification.  Part of the spring
strength requirement has to do with how the cam lobe is shaped near the open
point and closed point.  I would assume that cam manufacturers make their
cams so that as the lobe is reaching min and max lift, the ramp slows.  This
helps keep the valve train all touching.  Now I don't have the same numbers
available for Crane, Crower and others.  But this is how I judge a cam ramp.
There is more to cam selection than this though.  There is the weight of the
valve train.  This will limit rpms.  Of course you and I are not looking to
turn 7000.  So the weight won't be a big deal in terms of limiting rpms.

Like I said before I am not an expert.  I am a reader.  Which means I try
and read everything and judge the opinions that I read based on the how
logical is sounds.  So if I've got this all wrong, please someone let me
know.

One last thing, for Comp Cams, all of the springs besides the 972 are at
least double springs (not just a spring with a flat wound damper) and
require head machining to allow clearance for this extra spring.  It is
wound inside the other one.

Thanks
Paul
#9270


----- Original Message -----
From: Dennis Antenucci <itbewild@gte.net>
To: Paul Timko <thedrol@mediaone.net>
Sent: Tuesday, February 01, 2000 6:14 PM
Subject: Re: Roller vs hydraulic Cam


> Really? No significant difference on power at 5000-6000???!!!
> MD, who is obviously still learning :-)
> -----Original Message-----
> From: Paul Timko <thedrol@mediaone.net>
> To: Dennis Antenucci <itbewild@gte.net>
> Date: Tuesday, February 01, 2000 6:04 AM
> Subject: Re: Roller vs hydraulic Cam
>
>
> >solid lifter is going to be almost exactly the same as hydraulic roller
> >except for adjusting the valve lash.
> >
> >Paul
> >#9270
> >
> >----- Original Message -----
> >From: Dennis Antenucci <itbewild@gte.net>
> >To: Paul Timko <thedrol@mediaone.net>
> >Sent: Tuesday, February 01, 2000 1:35 AM
> >Subject: Re: Roller vs hydraulic Cam
> >
> >
> >> yea, I'm beginning to think the same thing...I am quickly running out
of
> >> cash too....so that will motivate me to live with a simple solid lifter
> >cam
> >> -----Original Message-----
> >> From: Paul Timko <thedrol@mediaone.net>
> >> To: Multiple recipients of list <detomaso@realbig.com>
> >> Date: Monday, January 31, 2000 9:00 PM
> >> Subject: Re: Roller vs hydraulic Cam
> >>
> >>
> >> >I was planning going the hyrdaulic roller route.  But I talked to a
tech
> >> guy
> >> >at Comp Cams.  He said that it wasn't worth the money (it's like a
$600
> >> >premium over a hydraulic flat tappet).  Now maybe I'm wrong, or maybe
> >he's
> >> >not really looking at it right, but it made some sense.  I haven't
> gotten
> >> >around to calling the Crane Cams guys yet.  They seem to have the
widest
> >> >selection of cams on the market, but it also seems like all of their
> >stuff
> >> >is around $1100 for the set as opposed to $300-$400.  This is for the
> >whole
> >> >valve train except rocker arms and valves but including a timing set.
> >> >
> >> >Paul
> >> >#9270
> >> >
> >> >----- Original Message -----
> >> >From: Tony DiGiovanna <t.digiovanna@mindspring.com>
> >> >To: Multiple recipients of list <detomaso@realbig.com>
> >> >Sent: Monday, January 17, 2000 7:25 PM
> >> >Subject: Roller vs hydraulic Cam
> >> >
> >> >
> >> >> This is a multi-part message in MIME format.
> >> >>
> >> >> ------=_NextPart_000_0128_01BF6127.F1942560
> >> >> Content-Type: text/plain;
> >> >> charset="iso-8859-1"
> >> >> Content-Transfer-Encoding: quoted-printable
> >> >>
> >> >> I've been playing with Cleveland engine simulations with the Desktop
=
> >> >> Dyno software.  I found a surprising torque increase by switching
from
> >a
> >> =
> >> >> conventional hydraulic cam to a hydraulic roller cam of low duration
> >and
> >> =
> >> >> high lift.
> >> >>
> >> >> Has anyone made such a switch on their engine and like to comment on
> >the
> >> =
> >> >> real world results?
> >> >>
> >> >> The cam I input is Crane PowerMax Hydraulic Roller HR-224/339-2S-12
> RF.
> >> =
> >> >> Is anyone running this or similar cam?
> >> >>
> >> >> The specs are as follows:
> >> >>       Degrees Duration @ .050 Int./Exh. Degrees Advertised Duration
=
> >> >> Int./Exh. Degree Lobe Separation Open/Close @.050" Cam Lift
Int./Exh.
> =
> >> >> Lash Hot Int./Exh. Gross Lift Int./Exh.=20
> >> >>       224
> >> >>       232 286
> >> >>       294 112 5    39
> >> >>       53   (1) .000
> >> >>       .000 .586
> >> >>       .609=20
> >> >>
> >> >>
> >> >> ------=_NextPart_000_0128_01BF6127.F1942560
> >> >> Content-Type: text/html;
> >> >> charset="iso-8859-1"
> >> >> Content-Transfer-Encoding: quoted-printable
> >> >>
> >> >> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
> >> >> <HTML>
> >> >> <META content=3D"text/html; charset=3Diso-8859-1" =
> >> >> http-equiv=3DContent-Type>
> >> >> <META content=3D"MSHTML 5.00.2614.3500" name=3DGENERATOR>
> >> >> <STYLE>
> >> >> </HEAD>
> >> >> <BODY bgColor=3D#ffffff>
> >> >> <DIV>I've been playing with Cleveland
> >engine
> >> =
> >> >> simulations=20
> >> >> with the Desktop Dyno software.  I found a
surprising torque
> >=
> >> >> increase=20
> >> >> by switching from a conventional hydraulic cam to a hydraulic roller
> >cam
> >> =
> >> >> of low=20
> >> >> duration and high lift.</FONT>
> >> >> <DIV> 
> >> >> <DIV>Has anyone made such a switch on
> their
> >=
> >> >> engine and=20
> >> >> like to comment on the real world results?</FONT>
> >> >> <DIV> 
> >> >> <DIV>The cam I input is Crane > >> face=3DArial=20
> >> >> size=3D2><B>PowerMax Hydraulic Roller HR-224/339-2S-12 =
> >> >> <B>RF. =20
> >> >> Is anyone running this or similar cam?</FONT>
> >> >> <DIV> 
> >> >> <DIV>The specs are as
> follows:</FONT>
> >> >> <DIV>
> >> >> <DIV align=3Dleft>
> >> >> <TABLE bgColor=3D#ffffff border=3D1 borderColor=3D#000000 =
> >> >> borderColorDark=3D#000000=20
> >> >> borderColorLight=3D#c0c0c0 cellSpacing=3D0 height=3D75 width=3D590>
> >> >>   <TBODY>
> >> >>   <TR>
> >> >>     <TD align=3Dmiddle height=3D48>> >> size=3D2><B>Degrees Duration @=20
> >> >>       .050 Int./Exh.</B>
> >> >>     <TD align=3Dmiddle height=3D48>> >> size=3D2><B>Degrees Advertised=20
> >> >>       Duration Int./Exh.</B>
> >> >>     <TD align=3Dmiddle height=3D48>size=3D2><B>Degree
> >> =
> >> >> Lobe=20
> >> >>       Separation</B>
> >> >>     <TD align=3Dmiddle height=3D48>> >> size=3D2><B>Open/Close @.050"=20
> >> >>       Cam Lift Int./Exh.</B>
> >> >>     <TD align=3Dmiddle height=3D48>Lash
> >=
> >> >> Hot=20
> >> >>       Int./Exh.</B>
> >> >>     <TD align=3Dmiddle height=3D48><B>Gross
> >=
> >> >> Lift=20
> >> >>       Int./Exh.</B>
> >> >>   <TR>
> >> >>     <TD align=3Dmiddle height=3D19>> >> size=3D2>224<BR>232
> >> >>     <TD align=3Dmiddle height=3D19>> >> size=3D2>286<BR>294
> >> >>     <TD align=3Dmiddle height=3D19>> >> size=3D2>112</FONT>
> >> >>     <TD align=3Dmiddle height=3D19>> >> size=3D2>5   =20
> >> >>       39<BR>53   (1)
> >> >>     <TD align=3Dmiddle height=3D19>> >> size=3D2>.000<BR>.000
> >> >>     <TD align=3Dmiddle height=3D19>> >>   =
> >> >>
> >>
> size=3D2>.586<BR>.609> >> ></DIV>
> >> >>
> >> >> ------=_NextPart_000_0128_01BF6127.F1942560--
> >> >>
> >> >>
> >> >
> >> >
> >>
> >
>

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