1939 Rolls-Royce Phantom III
1939 Rolls-Royce Phantom III. Click image to enlarge

Story and photo by Bill Vance

During the classic era of the 1930s many of the biggest most luxurious cars were fitted with large multi-cylindered engines. Eight cylinders was the minimum for acceptance into this prestigious circle, with both straight-eights and V8s being popular.

But it usually took even more to really break into the upper echelon, except if it was the straight-eight Duesenberg which was almost in a class by itself. Cadillac brought out a V16 in 1930, and a V12 in 1931. Marmon also had a V16. Packard had a V12 starting with its 1916 model and would carry it right through the 1930s. Lincoln had V12s, as did Auburn, Pierce-Arrow and Franklin.

In Europe the French Hispano-Suiza offered a V12, and the English Daimler came out in 1927 with the sleeve-valve V12 “Double Six”. Through all of this, Rolls-Royce, the company reputed to build “The Best Car in the World,” carried on with no more than six cylinders, apart from a short flirtation with a V8 in 1906.

It wasn’t that Rolls-Royce wasn’t familiar with large multi-cylindered engines. It had developed a V12 aviation engine in the 1920s, and its V12 Merlin aero engine was one of the most famous in the world.

Finally, in 1935 Rolls-Royce decided to consolidate its Best Car claim by joining the 12-cylinder club with the 1936 Phantom III. It was powered by a 60-degree, V12 with a bore and stroke of 82.5 X 114.3 mm (3.25 X 4.5 in.). which yielded a displacement of 7.3 litres (7,338 cc). Even though it was a twelve it was slightly smaller than the 7,668 cc inline six used in the Phantom II.

Although R-R was coy about quoting horsepower figures (they loftily described it as “adequate”), the 12 was estimated to develop at least 160 horsepower. This was increased to about 180 in 1938 when freer breathing cylinder heads were fitted.

Aluminum was used liberally throughout the engine, including cylinder heads, cylinder block and crankcase. The overhead valves were actuated by a single, gear-driven camshaft and pushrods, and hydraulic valve silencers kept valve lash at zero.

The engine was a wet sleeve design using cast iron cylinder liners, and the sturdy crankshaft turned in seven main bearings. With 12-volt twin ignition (24 spark plugs), two distributors and coils and four carburetors it was really like two sixes on a mutual crankcase. Engine warm-up was hastened by thermostatically controlled radiator shutters.

Power went to the rear wheels through a four-speed manual transmission that was separate from the engine. Its first gear had a very low “stump puller” ratio. Second gear was normally used for launching, and second, third and fourth gears were synchronized.

A low 4.25:1 axle ratio retained the flexibility to drop down to walking speed in top gear and then accelerate smoothly, a highly prized feature in those pre-automatic transmission days. The floor shifter was on the right, not in the middle, making entry and exit a little awkward.

Surprisingly, the brakes were still mechanically actuated by rods and cables, although they were boosted by a transmission-driven clutch-type servo motor. Suspension was independent in front (Rolls’s first) with coil springs, replacing the previous solid axle. Rear suspension was by semi-elliptic springs, and thechauffeur could periodically lubricate the chassis with a foot- operated pedal.

Shock absorber stiffness automatically increased as speed rose, or could be altered using a steering column-mounted lever, an idea still used today, although it’s now done electronically. And the loudness of the horn could be changed for city or country driving.

Interior appointments varied with the coachbuilder, but usually included perfume bottle holders, a hand mirror, spirits storage and glasses, a clock and fitted luggage. A rear window blind enhanced privacy.

The Phantom III was a big car, riding on a 3,609 mm (142 in.) wheelbase, and spanning 5,410 mm (213 in.) overall. Its weight of close to 2,722 kg (6,000 lb) was carried by huge 700 X 18 tires.

In spite of its mass, the big V-12 could haul it up to 96 km/h (60 mph) in 15 to 16 seconds, and top out at over 145 km/h (90 mph), or more depending on coachwork. It consumed gasoline at a rate of 10 to 14 mpg supplied by electric fuel pumps from the 186 litre (41 gallon) tank.

Phantom IIIs were made only until 1939 when production was halted by the Second World War. Following the war it was a changed world, and Rolls-Royce would revert to a six cylinder engine for its Silver Wraith model. It did not have regular overhead valves, but had an inlet-over-exhaust arrangement in which the inlet valves were in the head and exhausts in the block.

The Phantom III could be called the pinnacle of Rolls-Royce development. It would take a long time – 65 years – before there would once more be a V12 powered Rolls-Royce, this time the 2004 Phantom. But now it was not a Rolls-Royce built engine behind that majestic parthenon-shaped grille, it was a BMW. In an ironic twist of history, that German firm now owned what had been the most prestigious of England’s automobile builders.

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