maintenance

[Bob Culver]

The Big Seven engine is an intriguing contrast with the last 3 bearing Seven. The golden rule for a robust multi main bearing engine is that every main bearing must be rigidly supported.  The last Seven had the centre bearing very vaguely and flexibility dangling from a flimsy crankcase. With  no counterbalancing on the crank bearing loads at revs would have been high. The cars were notorious for broken cranks long before it was recognised as a Seven problem generally. The Big Seven is the other extreme. It has rigid one piece iron block/crankcase with the main bearing caps securely keyed in like a thoroughbred racer. And it has a crank with counterweights (a refinement omitted on the Eight).