Re: IML: 1958 Dash lighting

[Ken Miller <kdmiller44@xxxxxxxxxxx>]

Rex and List -

Here is a possible solution to your one of your questions.  This is from 
a posting I made to the IML in June of 1998 (almost eight years ago!).

Ken Miller
Portland, Oregon
Former Owner of Two 1957 Imperials
----------------------------------

Hello All:

There has been a lot of discussion lately about dash lights.  May I offer something I learned from owning two 1957 Imperials, one for 19 years.

Incandescent lamps exhibit an interesting characteristic.  If they are operated at less than their rated voltage (e.g., 11 volts on a 12-volt bulb), their life expectancy increases dramatically.  Of course, this doesn't come without some sort of penalty.  The penalty is that lamps operated at lower voltages deposit a black coating on the inside of the glass.  Over a period of time, this coating will make the bulb nearly opaque.

Dash light dimmer controls operate by reducing the voltage to the dash lights.  Even a control in good condition adds a little bit of voltage drop to the supply circuit to these lamps.  This causes dash bulbs to blacken over a period of years, although they almost never burn out.  

If your dash lights seem dim, it's a good idea to crawl under there and pull a few out to check on their blackness.  I have examined a number of Imperial instrument panels, and I always find these blackened bulbs.

The above does not apply to the electro-luminescent panels found in early 60s Imperials.


rex crews wrote:

> Group,
>
> I have a couple of questions for '57-'58 owners regarding dash 
> lighting.  On my '58 the speedometer lights up with black light and a 
> nice purple glow, powered by several #1891 bulbs; however, the 
> instrument light has only one large bulb in the center which gives off 
> a regular white light that vaguely illuminates the instruments.  This 
> shining center white light does not match the soft glow of the speedo, 
> but I cannot see that anything is missing.  Should there be a black 
> light insert in the center that has fallen out or do the two gauge 
> clusters have a different appearance?  And finally, is there any 
> reason to use a #1891 bulb rather than a #57, since they both have the 
> same candle power but a different shape?
>
> Thanks,
>
> Rex Crews   '58 and '60 Crowns


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