In a message dated 8/20/99 1:36:07 AM Pacific Daylight Time,
barneymg@ntsource.com writes:
> Hold on a sec. Back up a little before MGB times, say the '50s and early
> '60s. Earlier LBCs did not not use hot wire actuated gauges or voltage
> regulators. My MGA fuel gauge has the needle balanced between two opposing
> magnetic coils. It reacts similar to a simple analog volt meter and dances
> around as fast as the fuel can slosh in the tank. I'm rather used to it by
> now, but I can see how it may bother some people. I think the current on
> the sender wire is quite small, and a capacitor might do the trick.
>
> I notice the original note was posted to the healey list as well as the mgs
> list. How many other LBCs use a fuel gauge without a hot wire or
regulator?
Barney,
The type of gauge you describe as being in your MGA is called a cross field
gauge. They are still used today with the addition of a damping circuit
(small electronic board) that damping the sudden swings. One advantage of
the setup you have without damping is that your fuel gauge doubles as a G
meter, start with 1/2 tank of fuel the further up or down you can make the
needle go the higher the G load :-).
If you want to know if your car has cross field or a bimetallic gauge (so
called hot wire) when you turn on the key does the gauge register instantly
or does it take a moment to get to a correct reading? Instant reading
indicates a cross field gauge, a slower movement indicates a bimetallic type
gauge. Also for GM owners out there, if the gauges do not return to zero
after key off they are cross field gauges. Also if you want to know if the
circuit has a dampener in it, fill the tank with the key on. If the tank
reads full as soon as you are done, no dampener, if it takes a few minutes to
get the correct reading you have a dampener. Note: cycling the key should
cause a dampened gauge to read correctly instantly.
The purpose of the voltage regulator or voltage stabilizer is to ensure a
stable reading (10V?) even though system voltage may vary due to the normal
operation of the charging system.
One way to verify the swings are due to bad connections or fuel slosh would
be to sub in a resistor for the fuel sender. Ground one side of the resistor
and connect the other side to the sender wire. The reading should then be
steady as you drive the car, around corners, over bumps, etc. Any
fluctuations would indicate a bad connection.
Hope this helps,
Rick Ewald
|