Early L16's used 38mm inlets and also some L14 engines. These 38mm valves fit A series heads easily even using original seats in some late 1500 heads.

The valves are shortened, new collet grooves cut to suit the desired installed height of the spring retainers and the ends turned down for lash caps unless the stem ends are hot metal sprayed with stellite. The valves will work if not capped or tipped but the stem ends soon mushroom.
The lash cap provides a hard surface on the end of the valve for the rocker to rub on.

In engines where the valve stem sizes have been reduced to aid gas flow, a cap is fitted to the end of the valve stem to increase the surace area for the rocker arm to rub on.