Valve lash adjustment device
A lash adjustment device is for a valve train in a marine engine. The lash adjustment device comprises an external hollow body and a ball shaft that is telescopically movable in the hollow body. The ball shaft has a through-bore for receiving oil and having an annular lower end surface and an upper end surface. Oil flow into the hollow body pushes on the lower end surface and forces the ball shaft to telescope outwardly with respect to the hollow body. An absence of oil flow in the hollow body allows the ball shaft to telescope inwardly with respect to the hollow body until the annular lower end surface engages with an internal stop surface formed in the hollow body.
1. A method of making a valve train apparatus for an engine, the method comprising:
providing a roller that engages with a cam lobe of a cam shaft;
providing a rocker arm that carries the roller and has a first end for engagement with an engine valve that is biased into a closed position, wherein engagement between the roller and cam lobe opens the engine valve, and a second end for engagement with a lash adjuster for adjusting mechanical lash between the roller and the cam lobe;
providing the lash adjuster with a hollow body and a ball shaft that is telescopically movable in the hollow body, the ball shaft having a through-bore for receiving oil and having an annular lower end surface;
wherein oil flow into the hollow body forces the ball shaft to telescope outwardly with respect to the hollow body and engage the second end of the rocker arm to reduce mechanical lash;
wherein the hollow body and through-bore together define a clear passage through the lash adjustment device; and
wherein the lash adjuster is configured such that an absence of oil flow in the external hollow body allows the ball shaft to telescope inwardly with respect to the hollow body and increase mechanical lash until the annular lower end surface engages with an internal stop surface formed in the hollow body; and
selecting a location of the internal stop surface as a function of a desired mechanical lash at startup of the engine.