Connect to a port in the plenum if you want to get a proper reading Ken.
The vacuum in the runners is obviously cyclic - suck, squeeze, bang, blow -
right?   =)

If you still get a swinging needle at the plenum source, you have a
problem.

On Fri, Aug 21, 2009 at 9:20 PM, Ken Lewis <kdlewis@northstate.net> wrote:

>   I have searched the internet but can not find the answer.  All web sites
> state a "normal" engine's vacuum, at idle, is ~ 17 to 21 inches at the
> intake manifold. But, all these examples are for cars with one manifold
> connected to at least four cylinders. 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. Do I need to connect all test ports together to smooth these readings
> out or is this the problem?
> TIA
> Ken
>

--
Beverley Anne de Villiers   April 20, 1930 - July 4, 2009

Jake

1984 Vanagon GL
1986 Westy Weekender "Dixie"

Crescent Beach, BC

www.thebassspa.com
www.crescentbeachguitar.com
http://subyjake.googlepages.com/mydixiedarlin%27