Does anyone have any idea on why my 1959 ford custom 300's 292 y block has external oil tubing for the valve covers?
 

Does the system work....as in...does it oil the overhead without starving the main and rod bearing in the engine.  There were some that used a small orifice through two head pan studs that was to ensure that not to much oil pressure was lost to the rest of the engine.  If yours works fine and there are no issues.....leave it alone.  Overhead oiling is a big subject with y-blocks.  Be careful when changing something that works.  Seems like most people don't even want to discuss the subject.  LOL  Look on you tube.  Good luck.