09-12-2021, 04:46 PM
(This post was last modified: 09-12-2021, 04:58 PM by Bob Culver.)
A little background if you are curious. Very early cars had basic lubrication systems where oil was dripped or dribbled to the slow turning bearings. Then many had some form of low pressure circulation so oil flowed down to the main bearings and reservoirs were filled for the big ends and the rotating big ends scooped into these ie the Model T Ford and very many/most others. The system continued in Chev cars into the 1950s. When the scoops on the crank encounter oil it is smacked into the big end bearing with some force. The Seven is closely modelled on the Belgian FN motorcyle. The rolling main bearings need no special quantity supply. For the bigends, instead of filled reservoirs, low pressure oil jets point down to small scoops in the rotating crank. The system was also used on a model of the unusually small engined Bugatti Brescia sports/ racing car of about 1920 and earlier.
Many cars and all moderns adopt full pressure system with oil conducted to most bearings at considerable pressure. Involves drillings s in the crank and not very convenient for 4 cyl 2 bearing engines with rolling main bearings as feed to the bes cannot be from those. And centrifugal aspects complicate the somewaht long tortuous flow through the crank. The basic Seven system sometimes called "spit and hope" has been proven to remarkable rpm. A few sport and racing models were fully pressure fed and many of the current Seven racers favour it.
In cars before universal filters and modern detergent oils, one disadvantge of pressure feed was that a lot of oil was forced through the bearings and consequently, more dirt. Neverthelss cars as "recent" as the VW Beetle had no filter.
Many cars and all moderns adopt full pressure system with oil conducted to most bearings at considerable pressure. Involves drillings s in the crank and not very convenient for 4 cyl 2 bearing engines with rolling main bearings as feed to the bes cannot be from those. And centrifugal aspects complicate the somewaht long tortuous flow through the crank. The basic Seven system sometimes called "spit and hope" has been proven to remarkable rpm. A few sport and racing models were fully pressure fed and many of the current Seven racers favour it.
In cars before universal filters and modern detergent oils, one disadvantge of pressure feed was that a lot of oil was forced through the bearings and consequently, more dirt. Neverthelss cars as "recent" as the VW Beetle had no filter.