an internal combustion engine is equipped to supply the camshaft bearings with pressurized oil via a first dedicated oil gallery independently of the hydraulic lash adjusters and any valve deactivation devices which are supplied from a second dedicated oil gallery . the galleries may be connected at their downstream ends and a flow restriction is placed in a connecting passage or within each hla . an improved hla is similar to a prior art hla except that the prior art annular oil distribution groove in the outer surface of the hla body is eliminated to prevent communication of the primary engine oil gallery with the hla . the secondary gallery is formed remotely from the first oil gallery in the hla residence bore in the engine , and the hla is prevented from rotating within the residence bore .