I think there is far more to the story than has been exposed here.

 

The bearings are very large in area and if just wetted with oil will run for quite some time with light load and zero oil pressure. When I worked in the cabinet shop we had a jointer with 4 knives and a 60 pound rotor to carry them. It got a few drops of oil each morning, and ran just about all day. It had poured babbit bearings. It was 60 years old when I used it and is still running today, 35 years later.

 

A full throttle takeoff with no oil pressure would do it in with a high probability.

 

We did race for years without a windage plate between the engine and the pan. When braking hard, the entire oil supply would run up into the front cover and uncover the pickup.

Just a wiggle in the gage would indicate there was much reduced oil pressure. No damage ever resulted. 

 

Picture is my dry sump layout.

 

Lynn E. Hanover 

Lynn, I understand what you are talking about with respect to the bearings. Ed Anderson said there was some problem (not really identified as to what) that would cause the engine to run for as long as 20 seconds with no oil pressure! I know if you or I had an engine that wasn't showing oil pressure in 5 seconds we would be tearing it down to find out what was wrong. Ed said this was happening almost every time he started it, even when hot/warm. the engine should be primed at that point with oil pressure instantly, so something was very screwed up. He had run it for some time like that so the bearings were taking a beating at every engine start. The engine had to be pretty tough to hold up as long as it did. Your jointer example probably didn't run up to 2K rpm on start up every time either. A very small film will work for some time, but higher surface speeds require more lubrication at all times. Or perhaps I should clarify, they require the oil pressure to "float" the bearing. In a close fitted plain bearing wery little oil runs through at a given time. It depends on the design clearance.

Bill Jepson