Holden got its first engine building experiences during WW2, building aeroplane, boat and torpedo engines for the war effort. The Grey six (entire long motor was finished in grey paint) was born with its success to be seen as a measure of GM-H's new car. There was no requirement for the engine to break new ground but its reliabilty, durability and flexibility had to be first rate. The 6-cylinder design was settled on as a compromise between the British cars with their 4-cylinder engines and the US models featuring V8 donks.
It was a square engine, featuring a four-bearing crankshaft, gear-driven camshaft and full pressure lubrication system with provision for accessory oil filter. It had a capacity of 132.5 ci (2.15 litres), compression ratio of 6.8 and developed 60 bhp (rated at 21.6hp). Fuel system had cam driven mechanical fuel pump and single-barrel, manual choke downdraft Stromberg carby. An oil bath air cleaner was an optional accessory. Delco Remy electrics (starter, generator, distributor etc.) were used on early engines until Bosch units were phased in early 1953.
The torquey, low stress unit was extremely flexible, economical and offered at the time lively acceleration. An added benefit was that it was easy to work on. With its success through the '50s and early 1960's the grey engine was carried over into each new model series with only minor modifications - new camshaft, higher compression ratio, incorporation of larger valves and throat surgery in the form of improved carburetors. By the time the FB was released the capacity was up to 138ci (2.26 litres) with a compression ratio of 7.25 and an output of 75bhp (56 kW).
The Grey engine went into its 15th year of service under the bonnet of the EJ model, which ceased production in the middle of 1963.
