There are up to 20 bulbs related to the dashboard for gauges and instruments.
Which type ? Most of these informations are given by Geoff Wooton on the RROC forum.
Two types of bulbs are in use on the SY1 :
- T10 wedge are used for the gauges. The base is also called W2.1×9.5d. T10 wedge means that the bulb connects to the socket by the means of a wedge shaped base, usually glass. This coupling is also called push-in. Wedge bulbs are designated by a W. On the SY1 the original bulbs are 2 watts. But both W3W (3watt) and W5W (5watt) bulbs are suitable, according to the forum, providing an improved illumination. T10 are available in 6,12 and 24 Volts. For bulbs base reference see Here for details.
- miniature or midget E5 screw bulb are used for the dash switches (4 of them). E stands foe Edison and 5 for 5mm. The original lights have a blue soft plastic condom on them. If the condom is missing, you can cover the bulb with enamel paint, model makers type (Geoff's idea).
Source: The Rolls-Royce Forum - Australia
Voltage / Wattage All of the dasboard lights are 12V - 2.2W except for the two of them located in the ignition/ switchbox that are 16V - 32W (oil / ignition)
Wattage ranges from 1.5w (ignition switch illumination, hazard warning lamp) to 4w (flasher repeater lamps). All other lights are 2.2w. Source: Owners Manual 1968 - 2nd ed - 1975 reprint
Changing for LEDs "Replacing the dashboard and instrument bulbs with LEDs has tranformed the lighting in my car from barely visible to nicely illuminated".
Here are the links to the precise references :
For T10 : Here
For E5 midget :
Here Restrictions with LEDs :
LEDs are polarity sensitive so a wrong wiring will result into a faulty light.
Also, LEDs beeing either fully ON or OFF, they do not support the dimming function given by the "Pannel" switch.
Using lEDs for the warning lights pannel (coolant, breaks..) may not work for voltage reasons. Source: The Rolls-Royce Forum - Australia
Blue condoms There are two separate areas : the fascia and the central console. Typically the fascia bulbs appear to be using blue condoms. Using enamel painted leds gives a similar result. Source: The Rolls-Royce Forum - Australia
Fitting the bulbs Here is a top from the RR Australian forum : "using a clean bit of brake bleeding tube, fits over those miniscule bulbs (E5?) in the dash and makes them super easy to unscrew and change! " (Patrick Francis) Source: The Rolls-Royce Forum - Australia