Restoration guide

01 Engine

The clean ‘power-egg’ styling of the A50 and A65 unit-construction engines concealed internals little changed from the preceding A7 and A10 equivalents. The A70 crankcase assembly was different from the A65 and carried an A70 engine number. Within, there was still a 360° crankshaft assembly with a large central flywheel. This was supported with a timing side bush and a single roller bearing on the drive side. Conrods moved through an 85mm stroke with split big-ends fitted with replaceable shell bearings. A crankshaft pinion drove the single camshaft, above and behind the crank, and a skew gear the oil pump in the bottom of the timing chest. Almost everything was A70-specific. A few items can be