Editing Repco (section)

==Repco V8 engine==
In 1964 the Australian/New Zealand [[Tasman Series]] was created with a 2,500 cc capacity limit applied to engines. [[Jack Brabham]] approached Repco to develop a suitable engine, and together they decided to base the [[SOHC]] design on [[Oldsmobile Cutlass|Oldsmobile Jetfire]] 215&nbsp;ci block with six cylinder-head studs per cylinder. Combined with a short stroke [[V8 engine#Design|flat-plane]] crankshaft, Repco designed cylinder heads, camshafts and two-stage chain/gear cam drive, a 2.5 L engine was built in 1965 with its cylinder head cast by [[Commonwealth Aircraft]].

In 1963 the international motor racing body, the [[Fédération Internationale de l'Automobile|FIA]], announced that the maximum engine capacity for the [[Formula One]] category would be doubled to three&nbsp;litres to start from the [[1966 Formula One season|1966 season]]. Despite calls for a "return to power" having been made, few teams were prepared as the main engine supplier in the UK, [[Coventry Climax]], decided to get out of race engine building (under licence from Coventry Climax, Repco actually manufactured the 2.5L, Coventry Climax FPF [[4 cylinder|straight-4]] motor for the Australian and New Zealand racing markets).<ref>Setright, L.J.K. "Lotus: The Golden Mean", in Northey, Tom, ed. ''World of Automobiles'' (London: Orbis, 1974), Volume 11, p. 1232.</ref>

Jack Brabham used his friendship with engineer Phil Irving at Repco. He proposed they design and build a 3 L version of the 2.5 L engine by using a longer stroke [[V8 engine#Design|flat-plane]] crankshaft.

The Repco board agreed to his proposal in light of the expected rival 2.75&nbsp;L [[Coventry Climax FPF]] [[DOHC]] engine being of four-cylinder configuration deemed to be near-obsolete, and the plan to build the [[Cosworth DFV]] (revealed at the end of 1965 by [[Ford Motor Company|Ford]], its sponsor) was not known yet. A small team at Repco under Phil Irving developed the F1 engine, fitted with two valves per cylinder [[SOHC]] heads from the 2.5L version.

The first advantage of this Repco 620 V8 was its compact size and lightness, which allowed it to be bolted into an existing 1.5-litre Formula One chassis. With no more than {{cvt|310|bhp|0}}, the Repco was by far the least powerful of the new 3-litre engines, but unlike the others it was frugal, light and compact.<ref>Fearnley, Paul (May 2006) "The powerhouse that Jack built" [http://www.motorsportmagazine.com/ ''Motorsport''] p. 36</ref> Also unlike the others, it was reliable and due to low weight and power, the strain on chassis, suspension, brakes and tyres was low.<ref>{{cite web|url=https://www.statsf1.com/en/moteur-repco.aspx|title=Engine Repco - ''Stats F1''|access-date=28 June 2022}}</ref>

This engine being based on British/American [[Rover V8]]/[[Buick 215]] block<ref>Pinder, Simon (1995) ''Mr Repco Brabham Frank Hallam'' pp. 20–23 Pinder Publications</ref> is a common misconception. The Oldsmobile version of this engine, although sharing the same basic architecture, had cylinder heads and angled valve covers designed by Oldsmobile engineers to look like a traditional Olds V8 and was produced on a separate assembly line. [[Oldsmobile]]'s intention to produce a higher-powered, turbo-charged Jetfire version led to significant differences from the Buick 215, primarily in cylinder head design: Buick used a 5-bolt pattern around each cylinder where Oldsmobile used a 6-bolt pattern. The sixth bolt was added to the intake manifold side of the head, one extra bolt for each cylinder, meant to alleviate a head-warping problem on high-compression versions. This meant that Buick heads would fit on Oldsmobile blocks, but not vice versa. Changing the compression ratio on an Oldsmobile 215 required changing the heads, but on a Buick 215, only the pistons, which was less expensive and simpler. [[General Motors]] later use of parts diagrams drawn for [[Oldsmobile]] in [[Buick]] parts catalogue showing a six-stud cylinder block sowed further confusion.{{Citation needed|date=June 2017}} Later Rover versions of the aluminum block and subsequent Buick iron small blocks went to a 4-bolt-per-cylinder pattern.{{Relevance?|date=January 2020}}