05-09-2020, 04:55 PM
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#19
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Senior Member
Join Date: May 2010
Location: Windy City
Posts: 2,919
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Re: What Defines Over-Revving The Model A's Engine
Quote:
Originally Posted by johnbuckley
"....oil tray that feeds the dippers begins to suffer from 'windage' above 3200 rpm..." What's windage .. not come across the term before ( sorry I'm a Limey which explains a lot! )
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In addition to all the things Tobey said about 'windage' in the crankcase, vehicles with dipper lube of connecting rod bearings have another concern.
In a Model A with dipper trays the torrent of churning air in the crankcase can blow all the oil out of the four dipper tray recesses. Normally the hit of the con-rod scoop into a liquid oil pool results in a pressurized forcing of oil up into the bearing. When the oil gets blown away from the tray by windage the bearing only gets secondary lube from the oily mist.
Modern cars solve the windage oil pickup problem from their pans with a 'windage tray' that keeps the air torrent from churning up the entire pan contents into a froth. It is shaped just like a dipper tray, except it is not intended to hold several pools of oil for the rod dippers. It just drains and shields the four quarts below.
In a Model A the oil in the bottom of the pan is also protected from windage, just like in a modern car, but nothing protects oil in the four dipper valleys.
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