RE: Re: RE: rocker arms --ATTN. Frank Holloway

From: Holloway,Frank T (Frank.T.Holloway@KP.ORG)
Date: Thu Oct 15 1998 - 12:24:27 EDT


Tim,
Duration can be measured two ways, one a 0 valve lift and the preferred is
at .050 inch valve lift. The reason for the measurement at .050 is that it
is generally
accepted that flow doesn't occur until about .050 valve lift. If you change
the ratio of the rocker, it doesn't take as long (less degrees rotation of
the cam to reach
..050 valve lift). The same is true on the back side of the cam. Take a look
at the advertised duration figures @ .050 lift from the cam manufactures
where different
rocker arm ratios are available. You are right that "cam duration" doesn't
change, but if you are looking at the duration at the valve , it does, and
that's what really
counts. Maybe I should have said that by using the 1.7 ratio rocker arms,
your cam will act and feel as if it had and additional 10 degrees duration
and .025 inch
lift......
        Frank

> -----Original Message-----
> From: Tim [SMTP:magnum318@bewellnet.com]
> Sent: Tuesday, October 13, 1998 11:17 AM
> To: dakota-truck@buffnet.net
> Subject: DML: Re: RE: rocker arms --ATTN. Frank Holloway
>
>
> From: Tim Roller>magnum318@mail.bwn.net
> wed.11:08pm
>
> >>Frank--you mentioned that 1.7's gave more lift and duration. I
> understand
> the lift, BUT more duration? How is that possible--the cam grind
> determines
> what the duration is --Does the rocker change offset to the cam and make
> the valves hold open longer ? That's a new one on me, from all the engines
> I
> used to rebuild--that Would save a lot of money and time from changing out
> the cams to wilder grinds.
>
> -----Original Message-----
> From: Holloway,Frank T <Frank.T.Holloway@KP.ORG>
> To: 'dakota-truck@buffnet.net' <dakota-truck@buffnet.net>
> Date: Wednesday, October 14, 1998 9:48 AM
> Subject: DML: RE: rocker arms
>
>
> >Bill,
> >Factory rocker arm ratio is 1.6 I use the Crane roller rockers and I am
> >happy with them. If you want a higher ratio, Try Crower, they have a 1.7
> >(easier way to get
> >more lift and duration with the factory cam)....
> > Frank
> >
> >> -----Original Message-----
> >> From: William Blount Arthur [SMTP:m990198@nadn.navy.mil]
> >> Sent: Tuesday, October 13, 1998 9:56 PM
> >> To: dakota mailing list
> >> Subject: DML: rocker arms
> >>
> >> Do any of ya'll know what the stock rocker ratio is? Also, why wouldnt
> >> any roller rockers work on our trucks, we dont have shaft rockers as
> far
> >> as I know. If any of you have replaced the rocker arms with rollerized
> >> ones, do you like it and is it worth the $? Thanks.
> >>
> >> Bill
> >> '97 SS/T
> >



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