> I am trying to diagnose a flat four
> with four venturis and individual intake manifolds. When I  attach the
> vacuum gauge under a single venturi it produces rapid swings from zero to
> 20.

Hmmmm....  Maybe this is a 356?  ;-)

I have a Synchrometer, a German flow meter for measuring just
that.  I used to use it on my 911T when it had Weber carbs, and
when I had a 911T.  As I recall, since all the air down a venturus (?)
passes through this devicve, it tends to smooth it out.  You are
sure welcome to borrow it, if you wish.

PS: the scale on it runs 0-30 kg/h, with most of the scale 0-20.

Richard