Chuck, I'm not sure. I was just answering the question of why most cars
don't run manifold vacuum to their dizzy. I'llsend you the dissertation I
just sent richard on the hows & whys
Mark Haynes
> -----Original Message-----
> From: chuck [SMTP:chuckc@ibm.net]
> Sent: Wednesday, August 04, 1999 12:28 PM
> To: Haynes, Mark
> Cc: 'Richard Shipman'; spridgets@autox.team.net
> Subject: Re: Timing the 1275 ? (vac. advance with a sidedraft)
>
> Just walked in to this discussion.
>
> Does all this mean that I should re-plumb the vacuum
> on my '72 1275 with SUs? My vacuum also runs off the
> manifold. Is tehre a way to take it off the carbs?
>
> chuck
>
> Haynes, Mark wrote:
> >
> > Manifold vacuum decreases as your throttle plate opens. The dizzy wants
> full
> > advance at full throttle. if you use carb vacuum,the dizzy gets an
> > appropriate indication of the engines running demands otherwise, you get
> > less advance at full throttle, and more at idle . just the reverse of
> what
> > you relly want.
> > Mark Haynes
> > '62 Sprite XSP motor
> >
> > > -----Original Message-----
> > > From: Richard Shipman [SMTP:mbelect@mindspring.com]
> > > Sent: Wednesday, August 04, 1999 7:28 AM
> > > To: John MacDonald
> > > Cc: spridgets@autox.team.net
> > > Subject: Re: Timing the 1275 ? (vac. advance with a sidedraft)
> > >
> > > I don't understand... If the vacuum advance on my '74 Midget works
> with
> > > manifold vacuum, why won't manifold vacuum work with other
> > > configurations??
> > >
> > > Richard
> > > '74 Midget
> > > '68 MGBGT
> > > '58 Morris Minor
> > >
> > >
> > > >Variable vacuum. At the manifold it is 100% vacuum providing 100%
> > > advance
> > > >all the time. Just before the throttle plate it is variable.
> > >
> > > >
> > > >>Can anyone explain to me why my '74 Midget with SU's has a simple
> vacuum
> > > >>advance fitting right on top of the intake manifold and yet so much
> care
> > > >and
> > > >>attention is being taken to locate the vacuum pick-up at a specific
> > > point
> > > >on
> > > >>a sidedraft weber??
> > > >>
> > > >>What am I missing??
> > > >>
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