Vacuum Gauge

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CaliTrav
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Vacuum Gauge

Post by CaliTrav »

Hi All,

Just sense checking something - a while ago I bought a Smiths Vacuum Gauge, VL2301-00, and one of those carb inlet spacers with a pre-tapped hole and a nipple for the outlet to it.

The back of the gauge takes the same kind of fitting as an oil pressure gauge, so I bought an oil gauge pipe and clipped one end off, which feeds into a piece of rubber that fits snugly over the nipple and screwed the other end to the gauge. Any leaks would therefore be minimal as all connections are snug or tight.

However, I can't get it to register anything - the needle is almost all the way up inside, off the scale on the "good" side - which is where I guess it would be with no vacuum at all - but doesn't move while the car is running at all.

Am I missing something obvious with how I'm connecting it, or is it likely to be a duff gauge? I know the absence of a vacuum would cause it not to register, but there must be at least a partial vacuum in the tube, even if it didn't pull it down by much...
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mobylette
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Re: Vacuum Gauge

Post by mobylette »

You can easily test the gauge by sucking on the pipe to check for movement.
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Monty-4
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Re: Vacuum Gauge

Post by Monty-4 »

As per my thread here this is how mine looks during normal operation: https://youtu.be/KXcjanrie5U. :)

Good luck!
68' 4-door Saloon, another 'Monty'.
philthehill
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Re: Vacuum Gauge

Post by philthehill »

I like the driving gloves - very period. :wink:

A vacuum gauge is a very good means of obtaining maximum petrol economy.

MCYorks
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Re: Vacuum Gauge

Post by MCYorks »

Hi,
If I understand correctly the needle on this type of vacuum gauge should point to POOR when the gauge isn't connected to anything. i.e. there is no vacuum. If it shows GOOD all the time it could indicate the gauge is jammed.

During normal driving the gauge would show POOR during full throttle and GOOD when you release the throttle during overrun (which produces a high vacuum).
Hope this helps.
don58van
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Re: Vacuum Gauge

Post by don58van »

Hi
I have a Smiths vacuum gauge (not fitted). It is the type that has 5 zones on the dial with different colours. Each zone has a different description.

Its inactive position is fully anticlockwise 'poor'. When a vacuum is applied, the needle moves clockwise toward the other end of the scale (decelerate).

So I agree with MCYorks.

The needle could be stuck as suggested, OR the bellows/diaphram might be damaged from too much vacuum being applied OR the needle might need to be removed and repositioned to a different angle.

Don
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