Hi all,
My 1275 has the vacuum advance connected to the intake manifold. Do I
just have a different kind of distributor or is this the wrong
arrangement?
Jim Henderson
'69 Sprite MKIV HAN9U78817G
On Sun, 18 Jan 1998, Frank Clarici wrote:
> Trevor Boicey wrote:
> >
> > Mark Endicott wrote:
> > >
> > > I am in the process of installing a rebuilt set of SU's on my car and
> > > ran into a little problem. The vacuum line was attached to the front
> > > carbueretor on the originals. The rebuilts that I have don't have
> > > this port. I see that some earlier cars had the vacuum line attached
> > > to a port on the intake manifold. My manifold has a plug (screw) in
> > > this hole. Is there any reason not to connect a brass nipple to this
> > > port and use it for the vacuum advance?
> >
> > Likely not the same.
> >
> > The carb vacuum is probably ported vacuum, while the manifold
> > is (duh) manifold vacuum.
> >
> > The main difference in use is that manifold vacuum is highest
> > at idle/cruise, and goes down from there.
> >
> > Ported vacuum is near zero at idle, highest on strong
> > acceleration, then back down at cruise.
> >
> > The ported vacuum is taken from around the throttle plate
> > in such a way that the throttle blocks it when closed.
> >
> > If you switched to manifold, your timing would likely be
> > off especially at idle (or everywhere else if you set it
> > correct at idle).
>
> Mark
>
> Ditto what Trevor said.
> The manifold is a higher vacuum and will not work on the advance like the
>carb.
> You can drill a hole in the carb in front of the throttle plate and thread in
>a nipple for
> the advance.
> The throttle plate regulates the amount of vacuum so be sure it is on the
>front side of
> the plate. If you look closly there may be a flat spot on the carb body where
>the original
> fitting was, drill a small hole and thread it for a small nipple.
>
> Good luck
> --
> Frank Clarici
> Seeing all of you at Sprite Rush 98
> For more info on Sprite Rush, the 40th anniversery of the Sprite
> Check out my home page http://www.exit109.com/~spritenut
> ------------------------------------------------------------------
>
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