>> Mike,
>>
>> I believe a good test of the air intake system is to measure the
manifold vacuum you are generating.  I combed the archives on this topic a
while back it seems that anything over 18 in Hg is pretty good.  Below 15
or so and you should really go searching for a vacuum leak.
>
>Hi Jake, that sounds like a nice, direct test. How might this be done?

What you want to do is to measure the vacuum being generated at the air
plenum while the motor is running. All you need is an inexpensive vaccum
gauge.  I picked one up from a local industrial hose supply store for
$10.  It should have a range of 0-30 in Hg.  The highest vacuum I saw
reported in the archives was 27 in Hg (Stan Wilder on an AC van), but that
is rare.  Next, you need to come up with a way to expose the gauge to the
manifold vacuum.  I did this by inserting a plastic T in the vacuum line
that comes out of the passengers side of the air plenum and goes to the
fuel pressure regulator.  I then used a 1 inch piece of vacuum hose to
connect the gague to the unused port on the T fitting.  I own an air
cooled van and the vacuum line configuration may be different than on your
water cooled van, but the principle is the same.  I hope that helps.
Jake