Just try driving without any oil in the dashpots and you will have a terrible
flat spot due to the pistons rising without any restriction and giving a weak
mixture.
I recently was concerned about the pressure I had to exert on the
lift pins with
20w50 engine oil, I removed it and replaced it with 3in1 oil
and a flat spot on
acceleration, I then tried transmission oil, no flat spot
and gained about 2
MPG.
Don
OZ
________________________________
From:
Richard Ewald <richard.ewald@gmail.com>
To: Michael Salter
<msalter@precisionsportscar.com>
Cc: healey list <healeys@autox.team.net>
Sent: Thu, 12 August, 2010 12:26:50 PM
Subject: Re: [Healeys] carb oil
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@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@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@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
> >
_______________________________________________
> > Healeys@autox.team.net
> >
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