The oil leaves the vane pump located in the sump, and flows through a removable gauze filter, located in a separate well to the rear of the pump. From there it passes to the top of the sump, and through a gallery to the engine casting, and thence a vertical drilling in the rear wall of the timing chest. There it divides, and some of the oil passes on to the timing side bearing of the crankshaft, which is a plain bronze bush, which is also the pressure feed to the crankshaft (which is why it is a plain bearing rather than a ball bearing like the 350 and 600cc EWs and the OHV models.) The rest of the oil feeds the cam spindles as you noted. To get to the point where the circuit divides, the oil must lift the plunger of the indicator a little more than a quarter of an inch. This indicator rod resides in the vertical drilling mentioned in the rear wall of the timing chest. There is a pretty good illustration in the Care and Maintenance of the T6, S6, S5, C/31, D/31, E/31 Models handbook; reprints are currently available.
A picture of the oil indicator follows, I will post some dimensions tomorrow-
-Doug
