MK II SQ Top End 1953-58

For gasket sets click here; individual gaskets click here; pistons, rings and liners click here.

The MK II does not suffer with head gaskets blowing to the same degree as the MK I but they can and do blow but the problem can be overcome. The standard gaskets work very well but for extra piece of mind the ‘Otto’ gaskets are the business. Please read the notes on the MK I with respect to condition of threads, flatness of surfaces etc.  The studs should be tightened when the engine is cold as shown in the table below, note that these figures give an equivalent torque of 28 ft/lb when the engine is hot due to the differing rates of expansion of the aluminium head and the steel studs. Stud Initial torque with a new gasket Torque when re-tightening 1 to 4 and 11 to 14 15 ft/lb 10 ft/lb 7 to 10 19 ft/lb 14 ft/lb 5 & 6 and 15 to 18 22 ft/lb 17 ft/lb The above is based on research and theories by Bruce Longman, fount of all knowledge on Square Fours.

Head Studs For 1953 substitute the central, rear 0309 for an 0308 (use 198-53 nut and 118B-53 spacer).

The series A engines produced in early 1953 used the conventional location for the tappet adjuster over the valves; the series B engines have the adjusters over the push rods. This involved the use of different adjusters, adjuster lock nuts, rocker arms and push rods.

As the top end is fed by oil from the feed side of the oil pump rather than the return, over-oiling was always a problem leading to a smoky engine. Reducing the oil flow, as was done on the KH, was not really an option as this oil lubricates the cam and followers. An attempt was made to reduce the problem in 1955 by fitting a shroud to the valve guide along with a larger diameter valve spring to make room for it and an altered design of top spring collar and split collets. The valve guides were modified to give a ‘knife edge’ at the top so that oil was more likely to run down the side. At the same time the rocker arms were modified by chamfering the top edge, details of this modification are in the workshop manual.