When duration is measured, it's measured from a certain point (i.e. .006
valve lift, .004 tappet lift, .050 tappet lift, etc.) Duration is the number
of degrees it takes for the valve to pass this "mark" while opening and to
pass it again while closing. Because the 1.7's increase lift and ramp speed,
you'll get to the "mark" quicker and stay open longer before it gets back to
the "mark" again. This is the duration increase, though very small, and
insignificant IMHO.
Doug Myers
-------------
'99 Dakota RC/SB 5.2L/5-speed/3.92SG (soon to be 360 powered)
K&N Gen II, Hughes Stage 1 Intake, 180 T-stat, MP cam & lifters,
MP Timing Chain, MP headers, MP catback, MP plug wires, Accel Supercoil,
Custom Computer by Ron Zimmer, Centerforce Dual Friction Clutch
"Michael Clark" <mike@mikesdakota.com> wrote in message
news:6136454597.20010811023639@mikesdakota.com...
> > I was wanting the 1.7's because your effectively getting a "beefier" cam
with
> > reduced friction. I know if you were to go with installing a bigger cam
that
> > gas milleage is reduced. I was just wondering if the reduced friction be
enough
> > to take up the gas milleage for the drop of milleage from the longer
duration.
>
>
> Ok, feel free to kick me in the nuts if I'm wrong, but 1.7's don't
> increase the duration. They increase lift for sure, but I don't see
> any way they could increase the duration of a cam. Come to think of
> it, I don't see any way to change duration at all without changing the
cam.
> Am I right or wrong?
>
>
> --Mike
> www.mikesdakota.com
>
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