re :
I am trying to diagnose a flat four
> with four venturis and individual intake manifolds.

Then I guess you'll have to put a vacuum guage on each individual intake
manifold.
or run four small hoses to one junction, and take the vacuum reading there.

what kind of car and what symptom ?
porsche ?
pmail me if you want.
scott
www.turbovans.com

----- Original Message -----
From: "Jake de Villiers" <crescentbeachguitar@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, August 22, 2009 10:15 AM
Subject: Re: Friday question.Re: Vacuum gauge NVC

> 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