Keith, even if you have a fully functioning Pilgrim pump, the sight wells are vented to atmosphere via small diameter holes beneath the lipped edge of the ‘window frame’. The suction generated by the engine is partly proportional to engine revs, as every time that the piston rises it generates a partial vacuum, which is connected to the oil inlet pipes. More revs equals more suck…. A couple of days ago I sent an article about alternative oiling systems to Kev Bayliss. 🙂
