20 HP marker usage, with coil distributor wire NOT connected via a D50946/7/8 right-angle plug.
First 400(?) cars:

  E51070, Bush (Ignition Wires), 1 ea, on the coil wire (distributor end), style Z.

  E51071-6, Bush (Ignition Wires), 1 ea, at the distributor, style P.

  E17793-8, Wire Bush, 1 ea, at the spark plugs, style Gp.

  E18449, Chater Lea spark plug terminals as used on the late Ghosts are called for on all of the 20's.

We aren't sure what markers might have been used on those 20's with the optional E06 magneto. The 20 HP part books has some confusing words about this which we discuss below.

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It is not too surprising that the 20 HP series used the same marker styles as the late Ghosts. Unlike the Ghosts, there are existing drawings that show the ignition wiring details. There are 3 LOP's (E50878*, E51712*, and E52927*) and corresponding GA's on the RROC's 20 HP CD applicable to the first 1000 cars. The LOP's are under the Wire Fittings heading while the GA's are found under Ignition Wires or the two Ignition Wiring headings. The E50878 GA is incorrectly labeled in the listing as E91065, but the drawing itself is clearly marked with 'E50878'. All three of the LOP's are titled for 'Goshawk II'. 'Remarks/This Drawing Applies to the Following' in the upper right corner of each LOP lists the series of cars for which the drawing was intended. Additional 'Remarks' columns provide the number of cars in each listed series and 'Numbering Of' gives the beginning and ending vehicle numbers. These are not chassis numbers, but consecutive vehicle numbers starting with '1' for the first car built.

E50878* is applicable to "1, 250, 1-250; 2, 150, 251-400". It was for all 250 series 1 cars as well as the first 150 in series 2; in total, all cars from 1 through 400. Series 2 also had 250 cars, but at the 401st 20, the drawing was updated to E52712* labeled for "2, 100, 401-500; 3, 174, 501-674" - the last 100 of series 2 and the first 174 of series 3. During series 3, at vehicle 675, the drawing was updated to E52927* for "3, 76, 675-750; 4, 250, 751-1000" to complete the first 4 series and 1000 vehicles. 'The Rolls-Royce Motor Car' by Bird & Hallows labels these first 1000 20's as series A, B, C & D instead of 1, 2, 3 & 4 but they are the same cars. The next R-R LOP agrees with the Bird & Hallows convention and is labelled for 20 HP (not Goshawk II), series E onward.

All three of these LOP's for the first 1000 cars call for 6, Ebonite E17753-9 (style Gp) markers and 7, E51070-6 (styles Z & P) Brown Bakelite markers. These are the same part numbers as late Ghosts except there is only 1 set of Gp instead of the 3 sets needed for the dual spark plug Ghost. The GA E50878 shows a coil wire marker on the coil wire which enters the distributor cap from the top; the E51070 zero bush. We don't know exactly when, but at some point, the coil wire connection to the 20 distributor no longer came in to the top, but was connected at the side with a right angle plug, D50946/7/8. From that time forward, the 20 would likely not have used the zero numbered bush on the coil wire although they still continued to use the same Gp and P style markers elsewhere. No known cars of any model using the side coil connection had a numbered bush on the coil wire.

We think that this distributor change occurred at car 401, but we can't be certain. The LOP, E50878*, for the first 400 cars does not include the distributor plug part numbers, D50946/7/8, and the corresponding GA shows a coil wire entering the top of the distributor with a style Z marker in place. The next two drawing numbers, E52712 and E52927, exhibit a definite problem. Both of these LOP's include the distributor plug parts, D50946/7/8, and their GA's show a side distributor plug connection of the coil wire without an E51070 marker. But both of the later LOP's indicate that the E51070 marker was used. One or the other is wrong: either E51070 was used, or it was not. Except for the LOP, there is no other known support for use of an E51070 with the D50946/7/8 plug and present 20 HP owners seem to doubt that the E51070 was used on many of the cars. We therefore tend to believe that the zero coil wire marker went away after 20 HP number 400, but it might have been used as late as car number 1000. We have no doubt that the same styles of Ghost wire markers continued to be used (there were no other known styles yet introduced) but one has to add the detail of the changed coil wiring to decide whether or not a style Z, E51070, was also included.

On this first model of small HP R-R we learn that the drafting department was not infallible. Its not like wire markers were high on their list of 'must be correct' items. We are just now noticing the problem after 80 years. It seems there was a considerable amount of rote copying of information from old drawings when a new drawing was being generated. And it seems that quite often there were details from an earlier version included which are surely no longer applicable. One must study all of the available documents and information to decide what was likely done.

Not mentioned in these drawings are the 20's for which the E06 magneto was fitted as an option. According to the parts book issued February 1924 for the 20, these E06 cars used 2 sets of what we call style M(black) as well as 2 sets of our style B. Considering that the 20 has only a single set of spark plugs and the connection to the magneto is swapped for the coil wire input (depending upon which ignition is being used) it is difficult to fathom now 4 sets of markers might be used. The illustration of the wires in E53204* shows no markers at all on the single magneto wire. It seems to us that this parts book information is an example of copying from another drawing (PI?) without making all the required changes. We can't say what markers these 20 HP cars might have used. If you have an E06 20 HP let us know how you think its ignition wires were fitted.