First introduced in 1926, Percy Riley’s 9hp twin-cam four was an outstanding engine design by any standards, with various developments powering Riley cars until 1957. Looking to all intents and purposes like a twin-overhead-camshaft design, the Nine’s cross-flow cylinder head featured hemispherical combustion chambers and valves inclined at an included angle of 90 degrees.
The twin, gear-driven camshafts were mounted high in the block, operating the valves via short pushrods, this gave the advantage of a twin cam engine– but without the complexity. It quickly became apparent that the engine was highly tuneable and offered far more performance than was being achieved in standard factory output.
This potential was first spotted by J G Parry-Thomas and Reid Railton, being the first to demonstrate just how good it was at Brooklands. The success of their racer led to a production version, the Speed Model, which soon became known as the Brooklands Nine.
The sectioned engine shown here has been owned by Blue Diamond for a significant number of years and the block dates from 1929.
It is believed that it was originally part of a fully sectioned car, but now only the engine remains. (No doubt the sectioned chassis is now a ‘Special’ somewhere on the road!)
Found in the corner of the workshop, the engine was cleaned, polished, and painted ready for the annual Riley Register Rally at Coventry in 2015, this coincided with the official launch of the new company – Blue Diamond Riley Services Limited. Since this ‘launch’, the engine has found fame and fortune in the Riley Register Bulletin and travelled to the VSCC Prescott hill climb, where it had pride of place on the company’s stand. Its value to Riley enthusiasts and vintage car enthusiasts was proved by the large amount of interest it generated at Prescott. The ability to see the majority of the internal workings of any engine, never mind one with such racing pedigree was something enjoyed by young and old enthusiasts alike.
Now all we need to do is track down the rest of the sectioned car….