true , but what are we really working on here ?
what symptom.
usually when one is checking engine vacuum.....
it's about engine condition,
And , not to get all nitpicky .........but engine vacuum doesn't go through
the idle circuit exactly quite.
but whatever.
without knowing why we're discussing this, it's rather moot.

----- Original Message -----
From: "Richard A Jones" <Jones@COLORADO.EDU>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, August 22, 2009 2:37 PM
Subject: Re: Friday question.Re: Vacuum gauge NVC

>> The carb flow gauge - I have one I used on a Porsche 914-6
>> ( 6 individual throttle plates and intake manifolds ) ...that
>> tool  measures flow above the throttle plate.
>>
>> a vacuum gauge measures vacuum developed between the throttle
>> plate and intake valves.
>
>
> Yes, but....  With the plate closed, the "suction" the device
> sees is the vacuum pulling through the idle circuit.  That's
> what you are usually trying to balance with the Synchrometer.
>
> Richard