While replacing my camshaft and exhaust valves 78 750k I notice that the oil passages in the outer cam carrier/bearing that are just like the inner ones but don't go any further than the bottom of the carrier casting where it meets the head? including an o ring between the two. . but the passage stops there.for the inner bearings it continues on down the motor. The head from the older motor that I salvaged my cam and valves from is the same way only the o rings between the cam carriers and the head are diff size and seat diff. My first question now is how then does the outer bearings get lubrication. Secon, why the o rings if there's no oil flowing there and does it really need those I cuz lost one of mine and the ones from the other head are diff. Can I just stick any little slice of rubber in that recess between the head and carrier casting since the passage just ends there anyway ? Please explain