[Healeys] Carb Oil

[Steve Gerow]

Concurring with Mike Salter, 

At a recent dyno session, APT (www.aptfast.com) Advanced Performance
Technology stated that heavier dashpot oil creates more velocity and a
richer mixture on acceleration.

They are big fans of swapping the piston-return springs out to the next
heavier color. They said the combination of the spring stiffness and oil
thickness comprises the acceleration circuit in the SU.

 

Speculating here - it seems as though the oil would only affect mixture
during acceleration, whereas  a heavier spring would keep the piston
slightly further down  all the time against a given vacuum.

 

--

 

Steve Gerow

Pasadena, CA, USA

BN6

 

 

 

>>>>>>>>>>>>>>>> 

Richard Ewald <richard.ewald at gmail.com
<http://mbox.abrazosdata.com/compose.php?to=richard.ewald@gmail.com> >
To: Michael Salter
<msalter at precisionsportscar.com
<http://mbox.abrazosdata.com/compose.php?to=msalter@precisionsportscar.com>
>
Cc: healey list <healeys at autox.team.net
<http://mbox.abrazosdata.com/compose.php?to=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 at precisionsportscar.com
<http://mbox.abrazosdata.com/compose.php?to=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