It is essentially an economy measuring device: the higher the vacuum, the
less fuel is being used (does anyone have a better explanation?). But it
can also be used dynamically as a diagnostic device by watching the
response to opening or closing the throttle quickly. It is so long since I
have used one, that I cannot remember exactly how this works.
See: http://www.edelbrock.com/automotive/eps_sect2.html and
http://www.holley.com/HiOctn/TechServ/TechInfo/TI-219.html
for the use of a vacuum gauge in setting up a carb (but you do not need a
dashboard gauge for this).
A vacuum gauge simply measures the vacuum in the intake manifold. With the
throttle closed, it should measure almost 14 psi or 30 inches Hg or the
metric equivalent. With the throttle wide open it should fall almost to
zero. It can be connected through any convenient point to the manifold -
usually with a T piece to tap into an existing vacuum line.
Dashboard vacuum gauges still exist; I found one at:
http://www.edelbrock.com/automotive/eps_sect2.html
Trevor Jordan
74 TR6 CF29281U
At 13:26 +1000 3/10/97, Peter Zaborski wrote:
>What would you get by installing a vacuum gauge? Would it measure how
>much leakage there is in the vacuum system or something else? Where
>would it tie in with the vacuum lines?
>
>I have never heard of a vacuum gauge in a car (of course this could be
>an indicator of how much I know more than anything else...).
>
>Thanks,
>
>Peter Zaborski
>76 TR6 (CF58310 UO)
>Calgary AB Canada
>
>
>> -----Original Message-----
>> From: Trevor Jordan [SMTP:trevor.jordan@rmit.edu.au]
>> Sent: Thursday, October 02, 1997 6:06 PM
>> To: Peter Zaborski; 'Jeff S. Hapke'; 'TR6 List'
>> Subject: RE: rheostat
>>
>> I am starting to wonder whether I really want a rheostat to vary the
>> level
>> of instrument illumination - the rheostat position looks like a great
>> place
>> to put a 2 inch Smiths vacuum gauge which I have somewhere in the
>> garage.
>>
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