[Healeys] carb oil

Richard Ewald richard.ewald at gmail.com
Wed Aug 11 20:26:50 MDT 2010


Yes but does that higher flow rate more than offset the increased thickness
of the needle due to the piston not rising?
Venturi vacuum is very weak, and I can't see where even if the venturi
vacuum doubled it would overcome the lack of jet area.

On Wed, Aug 11, 2010 at 7:20 PM, Michael Salter <
msalter at precisionsportscar.com> wrote:

> The rate of flow over the bridge will be increased because of the
> higher vacuum created by the restriction of the piston.
> Higher flow rate produces a larger drop in pressure at the jet and the
> fuel flow is increased..
> All very simple really....    :)
>
> Michael Salter
>
> On Wed, Aug 11, 2010 at 8:32 PM, Richard Ewald <richard.ewald at gmail.com>
> wrote:
> > ::: Scratches head:::
> > The mixture would be too rich if the piston rises too slowly?
> > The higher the piston, the thinner the needle cross section at the top of
> > the jet.  The thinner the needle cross section the more fuel can be drawn
> > out of the jet.
> > So if too thick oil is used in the dash pots, the pistons will rise
> slower,
> > This would leave a thicker cross section of needle at the top of the jet,
> > and thus allow less fuel to be drawn into the engine.
> > Seems to me that using too thick an oil would give a lean mixture on a
> snap
> > throttle opening.
> > What am I missing?
> > Rick
> >
> >
> >
> > On Wed, Aug 11, 2010 at 3:44 PM, David Nock <healeydoc at sbcglobal.net>
> wrote:
> >
> >> If you use a oil that you use is way to thick the piston will be slow
> >> to rise and you will have a little to rich mixture when accelerating.
> >>
> >>
> >> David Nock
> >>
> >
> >
> >> British Car Specialists
> >> Stockton Ca 95205
> >> 209-948-8767
> >>
> >> www.britishcarspecialists.com
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