3 holes? try 6, 2 at either end of the head and 2 under the cams on the exhaust side side, the valve it the block is a restrictor to help oil pressure, theres nothing in it just makes the hole smaller to increse oil pressure, in the 8v its mounted in the head.
description on epc says its a one way valve . Its located in the oil way to the head.
Just thought this mite be the cause of my oil light taking a while to go out due to the oil draining back down over night on the pressure side