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QUESTION: I am considering installing a vacuum gauge in
my Ford 460 in a class A MH. Is this a big deal
to find the appropriate vacuum hose to tie into ? ?
Thanks
ANSWER: I would get as close to the intake valves as possible. Trace back toward the
air cleaner and put a T in the first vacuum hose.
You can also drill the intake manifold -- preferably at about center. Tap for
a hose barb.
Go to the intake manifold and look for an existing fitting (might look
like a bouquet of little hoses). If no spares, go to auto parts store and
get a "Y" or "T" fitting that is sized for an existing hose and your gauge
hose. Cut the existing hose at a convenient location and reconnect thru
T/Y (Best if you select an existing hose that is "loose" on both ends,
rather than one moulded into another vacuum device).
If no fitting at all is present, look for a screw-in plug you can remove
and replace with a fitting. While you're at it, check all your existing
hoses for hardness, leaks and existence (sometimes the caps disappear, esp
if you've had a backfire).
Objective is to get "raw", unaltered vacuum to measure. Read instructions
that should have come with gauge.
There are two types of vacuum you will encounter - ported or manifold.
Manifold vacuum is relatively constant and does not change with the
opening or closing of the throttle. An example of this would be the
source used to power up vacuum assisted power brakes.
Ported vacuum changes with the position of the throttle. This is the
source you need to tap in order to hook up your vacuum gauge. Check
different locations by hooking your gauge into the possible donor hose
BEFORE you do any cutting and teeing.
Drilling and tapping the manifold is not encouraged since the filings
will find themselves into your intake system and then into the engine.
Once you have the gauge installed, you will be guaranteed to increase
your mileage by simply watching the change in vacuum as you drive at
different speeds. It is often a real eye opener to see how much head
winds affect the performance of the engine - something you quantify with
the gauge.
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