The big changes to the DB2 engine came with the introduction of the DB2/4 Mk3 in 1957 and owe their existence to the arrival of a new Aston Martin engine designer, Tadek Marek, a naturalised Pole, who joined the company in 1955. The major changes included the introduction of a redesigned cylinder block of 3 litre capacity, enabling the removal of the previous liner offsets, top seating wet cylinder liners, a modified cylinder head with enlarged intake valve seatings and a substantial increase in the size of the oil pump. The crankshaft design was also slightly modified. Corresponding improvements to the free breathing of the intake manifolds and a freer flowing exhaust system were also added with an increase in compression ratio. The Vantage specification camshafts and carburettors were standardised.
The Mk3 engine was also offered with a higher performance option, this being the DBD engine. This variant came with triple H6 SU carburettors.