Holden Straight-six Motor - Grey

The Grey motor built between 1948 and 1962, earned its name as the engine block was painted grey. This overhead valve engine was first fitted to the Holden 48-215 and mated to a three-speed column change gearbox. A three-speed GM Roto-Hydramatic 240 automatic transmission was an option fitted in the latter EK and EJ series. The engine was based on a Buick pre-World War II design, and saw only minor changes throughout its 15-year life.

It displaced 132.5 cubic inches (2.2 L) in its original form, and was bored out to 138 cubic inches (2.3 L) when the FB series was introduced in 1960. It developed 60 brake horsepower (45 kW) at 5000 rpm, providing superior performance to the competing four-cylinder Austin, Morris, Vauxhall and Ford of Britain vehicles. The grey motor featured a compression ratio (7.5:1, low stress design with a view to high reliability. Due to sheer ubiquity, they were popular for racing, and were fitted to many open-wheelers, as well as racing Holdens. With the engine's low-end torque, they also found their way into boats and machinery such as forklift trucks.

This engine ran a seven-port non-crossflow cast-iron cylinder head. There were three siamese (shared) inlet ports for cylinders 1-2, 3-4 and 5-6, two individual exhaust ports for cylinders 1 and 6, and two siamese exhaust ports for cylinders 2-3 and 4-5 in a layout on one side of the head casting. The inlets were fed by a single barrel Stromberg carburettor in common and fitted with a traditional Kettering ignition by coil and distributor. The electric system was six volts in the 48-215 and FJ.. The earliest grey motors (approximately 100,000) were fitted with Delco-Remy accessories, although Lucas and Bosch equivalents throughout the motor’s lifetime replaced these.

The very first production grey motor (1948) was number 1001, and they continued in a single sequence until July 1956, when the prefix "L" was introduced. The change affected all engines numbered L283373 and above, signifying the 12 volt negative earth engines as fitted to the all new FE model. The prefix "U" was introduced for motors with the original electricals as fitted to the FJ utility and panel van models, which ended in February and May 1957 respectively. The change was effective from engine U283384. The prefix "B" was introduced and the number sequence reset with the introduction of the 138 cubic inches (2.3 L) displacement engine, and ultimately this was replaced by a "J" prefix for motors fitted to EJ vehicles in 1962.