A general view of the fan, the wrong way round, in relation to the pump, alternator and radiator. The free end of the measure is against the back of the radiator core.

Logically this should be the side of the fan that faces the engine, with the concave and smoothest surface best able to push the air towards the engine i.e. pull it through the radiator.

This should be the side that faces the radiator. Note how much higher the central boss is off the ground, which alters the relative distances between blades, engine and radiator according to which way round the fan is mounted.

Steve Loft's engine clearly showing the spacer mine lacks, and the blades the correct way round.

2nd-hand spacer. Not pretty but serviceable.

It is 7/8" thick, and has tapered sides being 3 1/8" across the flat face and 3 1/16" across the recessed face. Presumably it will be obvious which way round it goes from the relative diameters of the pulley and fan faces, but in the Parts Catalogue it is shown with the flat (wider) face forwards.

Spacer cleaned up, fan repainted, and now the right way round.

David Bolton's 6-blade fan on a UK 72 shown for comparison. Note the long-nose pump and pulley, and hence no spacer and short bolts (however it could be a short-nosed pump with the spacer inside the deep pulley). Note all these fans rotate clockwise when viewed from the front of the car.

Fan correctly orientated, with the deep dish facing away from the engine, and the slightly curved leading edge of the blades for clock-wise rotation.

Correctly orientated, blades well clear of thermostat housing, alternator etc.

Fan the wrong way round, blades fouling engine parts.

Arrow showing direction of rotation, anti-clockwise when viewed from the front of the car.

Showing clearly defined blunt leading and tapered trailing edges.