ROLLS-ROYCE PHANTOM II SCRATCH BUILT COMPONENTS & MODIFICATIONS
Drawings & Guides Introduction
The Pocher kits are recognized as some of the most complex and detailed automobile kits ever made. Nevertheless compromises were inevitably made for production and commercial reasons. That leaves the door open for the bravehearted to fix production quality issues, correct errors and, more importantly, add detail. The following pages describe & dimension some of the corrections and super detail modifications that can be made to the Rolls-Royce kits.
A word of caution, however the pages can be intimidating. They are designed for the advanced modeler and preferably someone comfortable reading an engineering drawing. Although details on components and assemblies are provided, there are no step-by-step-by-step assembly instructions. Familiarity with the Pocher Rolls-Royce kit is assumed.
The Pocher Rolls-Royce kits are historically inaccurate, mixing a variety of components from different years of production. Some of those inaccuracies are pointed out in these notes along with ways to correct them. The notes are based on Rolls-Royce drawings and photographs of prototypes.
The pages shamelessly mix both English and metric dimensions. In addition, any scratch builder is also obliged to deal with other dimensional systems for items such as wire, drills and hardware. The last page is a matrix that attempts to link all those systems across the range of dimensions most likely to be used. Hopefully it will be a useful reference tool.
Using the Pocher kit as a platform for building an historically accurate, detailed model of the Rolls-Royce Phantom II is a long, but very rewarding journey. I trust these notes will help.
PROTOTYPES: MAJOR VISIBLE CHANGES & TIMING
This chart shows the major visible changes made to the Phantom II during its life. Each column represents an historically correct configuration. The black bars are the Pocher features. They are clearly a mix of components from different years of production.
FIRING ORDER & VALVE POSITIONS
The valves on the Pocher cylinder head are all in the same, closed, position. But, to be correct, at least two valves would always be open. For those valves, the springs would be compressed and the rocker arms tilted. The firing order and crankshaft position determine which valves are open. Of course, if you never intend to remove the rocker cover, none of this really matters!!
Typical Four-Stroke Cycle
With a four-stroke cycle and the Phantom II firing order of 142635, the sequence of the positions of the pistons thru the cycle are shown in the matrix on the right. Pistons 1&6 are always in the same position, as are 2&5, and 3&4. For example, the box shows that when Cylinder 1 has fired and its piston is just past top dead center (TDC), the exhaust valve for cylinder 3 is open and the inlet valve for cylinder 6 is open. These are shown in red.
CARBURETOR MOUNTING
The Pocher carburetor is not to scale. Model Motor Cars offers an outstanding resin model which is. This note describes the mounting to the inlet manifold. Subsequent pages will describe the modifications for the control levers.
1932 CARBURETOR
In January 1932, the carburetor was changed to the one shown below center. Although structurally similar to the Pocher and Model Motor Cars carburetors , there are distinct differences such as the air cleaner. Control lever arrangements were virtually identical. The following two page note describes the conversion of a Model Motor Cars resin carburetor to something closer to this variant, if that’s what you choose to use.