Brad Kahler wrote:
>
> When I first start my Spitfire Mk1 the temperature gauge needle
> quivers like crazy. After the engine starts getting hotter the
> needle settles down and seems to perform ok. Has anyone seen
> anything like this before? I do know the charging system is not yet
> up to snuff and the voltage is typically somewhere around 12.7 volts.
> Could this be the problem, or could it be a bad voltage stabilizer.
> I would think if it was the voltage stabilizer then the needle would
> not stop quivering.
>
> Anyone have any thoughts on this?
For the first 30 seconds to a minute of running time, I think this is
fairly common. In fact, the quivering _is_ due to the voltage
stabilizer. It has a miniature set of points attached to a bimetallic
strip. When the bimetallic strip is cold, it has fairly solid contact,
heats up very quickly, breaks contact, cools, makes contact, cools. The
gauge reacts to the on-off voltage with jerky behavior. With a little
time, all the components inside the voltage stabilizer (including both
sides of the bimetallic strip) warm up from current passing through
them, and the quiver diminishes. If it goes on for several minutes, the
stabilizer is probably needs replacing.
Voltage stabilizer is a bit of a misnomer. It's actually a voltage
reduction device, taking battery voltage down to an average of 10 volts.
It does this (when warm) by vibrating open and closed many times a
second. Essentially, the gauges see 12 volts, nothing, 12 volts,
nothing, and the average is about 10 volts.
Cheers.
--
My other Triumph runs, but....
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