Triumph TR8 V8 Oil Pump and Filter
Differences Between Oil Pumps
The oil pump of the Rover V8 engine, from its introduction in the 1960's until late 1994, comprises a pair of pump gears which rotate inside a housing in the timing cover. One gear - the idler - is driven by the other, which includes a shaft that is driven off the end of the distributor. The distributor, in turn, is driven by a skew gear on the end of the camshaft.
Pre SD1-era Rover V8 engines (including Rover P5, P6 and early Range Rover) feature a pair of "short" oil pump gears, the driven shaft of which has a slot into which the tooth of the distributor shaft engages.
From 1976 (SD1-era), the oil pump is improved by longer gears, the driven shaft of which is now toothed to engage in a slot in the distributor shaft.
For two reasons, the two types are not interchangeable: