Originally Posted by oldbogie
The Olds flows from the main galley via a drilling to each main bearing. It then taps drillings for the lifter galleys and the cam bearings using the back side of the bearing shell to close the passage.
I'm afraid that is not quite correct for Olds motors. Please see posts #3 and #7 above. The Olds oiling diagram is in the factory Chassis Service Manual. Oil from the pump flows directly to the main gallery that is the one that feeds the driver's side lifters first. A drilled passage from this gallery then feeds each of the mains, and from there additional passages feed the passenger side lifters and the cam bearings. Unlike Chevy motors, there is no dedicated main gallery that feeds the main bearings first. The only way to restrict oil to the rockers is with restrictors in the lifter feed holes, or with restricted pushrods.
As a side note, I have GM factory service manuals spanning the 1940s through the 1990s, from Olds, Chevy, and Cadillac, and every one of them calls these passages oil galleries, not galleys. Per Webster, one definition of gallery is a long narrow passage.