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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