Dave wrote:I am not sure why they didn't look at local production of the SBC but instead went across to a completely new V8 engine.
I have a copy of Car Australia magazine dated April 1994. That year marked the 25th anniversary of the Holden V8 and the magazine featured an excellent story of the development of the engine as told by Fred James, the engineer in charge of designing it.
Work on it commenced in 1963 with a feasibility study and it became clear the following year that the new engine would be a V8 after Fred toured GM facilities in the US as well as Vauxhall and Opel in Europe. The trend was to bigger cars and it was thought a V8 would be more efficient and smoother than a large six.
Some thought was given to using the SBC but the first Holden destined to receive a V8 was the HK and the Chev would not fit. The Chev's block was offset to the left so the left hand cylinders were ahead of the right hand bank of cylinders. This was intended to suit a left hand drive car. When fitted to a HK it interfered with the brakes and steering creating a major problems that could not be easily overcome.
In 1966 Detroit ordered the HK be lengthened by three inches allowing the Chev to fit. That could have been the end of any plans for a locally made engine because the project was still in is infancy and little money had been spent on tooling. The Chev engine still presented many minor problems in adapting it to a right hand drive car and this made it very expensive.
There was also a national push developing for an Australian designed engine (apparently all of the sixes had been designed in Detroit with little local input although Fred, and probably a few others, worked on the engines in Detroit) and many people wanted it including the American general managers at that time so the decision was made to go ahead.
While the engine was to be locally designed it had to conform to Corporation standards so Fred was sent overseas again. He was able to take whatever technology he liked from all other GM divisions. The design team had to do something better than what was either in production or contemplated by the US divisions. The engine had to be shorter, narrower, lower in height and above all it had to be lighter than anything else available.
In 1966 the engine was to have 237 and 292 cubic inches. This gradually increased and 253 and 308 was finally settled on after the sales department demanded more cubic inches than Ford's 289.
It finally went into production with the HT in 1969 with the SBC filling in during the HK period.
By the way Dave there was more than one "new head" designed for the Grey engine. I can remember the Repco cross flow, the Dunstan rotary valve and the Waggot twin cam. Who knows, there could have even been more.
I have a 1957 copy of Wheels magazine that shows an engine with the Waggot head. It was setup for use in a boat and had six Amal bike carbs.