An apparatus for the adjustment of the valve control of a reciprocating piston internal combustion engine with a cam shaft driven from the crankshaft by an endless, flexible transmission member, in which the cam shaft and a valve control adjustment device are brought into engagement with each other by a control member arranged transversely to the plane of the separating surface of a control space housing with a loosened threaded connection; the driving gear is nonrotatably fixed with respect to the cam shaft by way of the transmission member drivingly connected with the crankshaft and tensioned by a tensioning roller while the crankshaft is nonrotatably fixed in the top dead center position with respect to the crankcase by a locking pin.