This blog, in addition to the usual maintenance details for classic mini cars, an attempt is made to explain the "whys" and "wherefores" of the various jobs.

Thursday, 15 October 2009

Excessive Fuel Consumption

Flooding or too high a petrol level in the float chamber is, of course, one of the most likely causes of abnormally-high fuel consumption. The carburettor, however, is often blamed for heavy consumption when the trouble is in fact due to poor condition of the engine and ignition systc-m, as described above, or to over-retarding of the ignition timing. Binding brakes arc another common cause.

Short journeys and town driving will increase the petrol consumption quite appreciably. The average figure is generally slated by car manu¬facturers in terms of country running over give-and-take roads with normal loads, at a speed of between 30 and 35 m.p.h., when about 40 m.p.g. is reasonable; but the actual consumption may vary between 30 m.p.g. when driving at full throttle on a motorway and 55 m.p.g. during the course of quiet pottering on country roads.

If consumption is considered to be too high and the carburettor, ignition system and engine are in good mechanical condition and correctly adjusted, the owner who puts fuel consumption before performance can try the effect of fitting the economy or "weak" jet needle recommended.