vaguum gauge

[stagjim1]

Hi members can any one tell me is it worth fitting vaguum gauge and if so would it help to drive more economicall, my friend says I could save
on petrol plus wear and tear to the engine.he.s he right or wrong.your comments please.

jim

[cosmicwheels]

Hi Jim, I set my timing and my carb idle[weber] with mine, I think its like marmite .[ love them or hate them],I drilled the take off in the middle of the servo bango bolt off the car, hope this helps John

[jakesmig]

Your friend is generally correct, and if you fit one you will obsess more about it than the temp guage.
Vacum takeoff is what operated the economy quage on Beemers and the green, yellow & red lights on Renaults etc.

[davidf]

Always used to have one on my minis; it gave advanced warning of the regular need to regrind valves!

So, I fitted one to my first Stag when I first had the car.

It does give a good indication of how hard you are driving. But don't get too distracted from the road!!!

It also gives a good indication if everything is OK at tick-over; if it is pulling less vacuum than normal, then you have a leak, or a problem with tuning (timing, carbs, ..)

Also, I will repeat a story I recounted earlier.


I have my inlet manifold vacuum gauge tee'd into the brake servo pipe. Seems to have worked Ok for 20-odd years!

(Well, apart from the time Stag paranoia set in on the way out of Andorra back into France. Got stuck in a traffic jam just on the summit of Port d'Envalira. Idly glancing at the gauges, I noticed the tickover vacuum was lower than usual - about 15 ins Hg instead of about 20. So, I start mentally listing all possible causes, and thinking what other symptoms would go with each cause. None of these other symptoms were apparent. After we got through the queue for the border, and continued towards Ax-les-Thermes, I checked the vacuum every time I took my foot off the throttle for a bend. The problem seemed to be curing. If there is one thing worse than a problem occuring on holiday, it is one that won't stay consistent long enough to analyse it! Then, one of my daughters complained her ears were hurting. "Ah!", said I, knowingly, "that is because we have come down from an exceptionally high mountain pass, and the air pressure was much lower up there". And then it dawned! That is why the vacuum gauge was reading low - atmospheric pressure at 2408 metres above sea level is about 75% of sea level pressure, and the inlet vacuum is a given fraction of atmospheric pressure! So, the vacuum reading was "normal" at 75% of what I was used to. Lesson - again - ignore the gauges and enjoy the view!)

[stagjim1]

Thanks David for you comment.i will think about fitting on.

jim

[stagjim1]

Hi cosmicwheels than you for your comment

jim

[wilf]

For me, a vac gauge is a diagnostic and setting up tool, not a day to day measurement that I need.

[jleyton]

Interesting story David - glad you sussed it out

Cheers

Julian

[Stagdad]

As a driving style tool it will tell you what you already know, more right foot = less mpg