An engine block, comprising: a cam rail comprising a rotating eccentric cam; a follower, comprising: a first end in contact with the rotating eccentric cam; a second end configured to contact with a portion of a valve train mechanism configured to open and close a fluid pathway of a combustion cylinder; a body extending between the first end and the second end; and a fluid port; an oil gallery bore parallel to the cam rail, the oil gallery bore configured to supply fluid to the follower fluid port; and a gallery insert in the oil gallery bore, the gallery insert configured to abut the follower body to prevent rotation of the follower with respect to the cam rail, the engine block further comprising a plurality of followers aligned with the follower, wherein the oil gallery bore is configured to supply fluid to the plurality of followers, and wherein the gallery insert in the oil gallery bore is configured to abut the respective followers to simultaneously prevent rotation of the respective followers with respect to the cam rail; characterized in that: the oil gallery bore comprises an internal surface and the gallery insert further comprises: a first end that extends out from the oil gallery bore to abut the followers to prevent rotation of the followers with respect to the cam rail; and a second end that either extends out from the oil gallery bore to abut the followers to prevent rotation of the followers with respect to the cam rail; or abuts the internal surface of the oil gallery bore. a cam rail comprising a rotating eccentric cam; a follower, comprising: a first end in contact with the rotating eccentric cam; a second end configured to contact with a portion of a valve train mechanism configured to open and close a fluid pathway of a combustion cylinder; a body extending between the first end and the second end; and a fluid port; a first end in contact with the rotating eccentric cam; a second end configured to contact with a portion of a valve train mechanism configured to open and close a fluid pathway of a combustion cylinder; a body extending between the first end and the second end; and a fluid port; an oil gallery bore parallel to the cam rail, the oil gallery bore configured to supply fluid to the follower fluid port; and a gallery insert in the oil gallery bore, the gallery insert configured to abut the follower body to prevent rotation of the follower with respect to the cam rail, the engine block further comprising a plurality of followers aligned with the follower, wherein the oil gallery bore is configured to supply fluid to the plurality of followers, and wherein the gallery insert in the oil gallery bore is configured to abut the respective followers to simultaneously prevent rotation of the respective followers with respect to the cam rail; characterized in that: the oil gallery bore comprises an internal surface and the gallery insert further comprises: a first end that extends out from the oil gallery bore to abut the followers to prevent rotation of the followers with respect to the cam rail; and a second end that either extends out from the oil gallery bore to abut the followers to prevent rotation of the followers with respect to the cam rail; or abuts the internal surface of the oil gallery bore. a first end that extends out from the oil gallery bore to abut the followers to prevent rotation of the followers with respect to the cam rail; and a second end that either extends out from the oil gallery bore to abut the followers to prevent rotation of the followers with respect to the cam rail; or abuts the internal surface of the oil gallery bore.