Abstract: A roller type tappet body has a tappet, a lock pin type guide member, and axial guide grooves which cooperate with one another to secure the body against rotation, an axial guide groove in the cylindrical tappet bore that guides the tappet body into the cylinder block or head being formed from the remaining part of a small longitudinally extending bore that is initially bored and subsequently opened by the boring of the larger cylindrical tappet bore to form a semicircular cross-section, the guide member being secured to the tappet body and formed with a round or partly round cross-section from a cover plate for a portion of the tappet assembly.