Triumph MAYFLOWER 1951, Instruction Book

Page: 51 / 86

50
RUNNING ADJUSTMENTS— Engine
DECARBONISING AND VALVE GRINDING
It is recommended that the cylinder head be removed for decarbonising and valve grinding
after the first 5,000 miles (8,000 km.). This is chiefly to give attention to the valve seats,
the metal of which becomes stabilised during this period. Thereafter it will be found that
decarbonisation will be required only after a period of about 15,000 miles (24,000 km.).
Providing that the engine is running satisfactorily after this period and that each cylinder
gives a normal compression, showing that the valves are seating reasonably well, it is
much better to leave it alone and delay decarbonising for as long as the engine continues to
run satisfactorily.
Operations such as decarbonisation and valve grinding should be carried out by the skilled
mechanics at your nearest Triumph Agent, but for those who desire to do this work
themselves the main points to watch are outlined below:
1. Use a tool made of some soft material such as solder for removing the carbon.
2. For decarbonising it is not necessary to remove the tappet guide blocks. If,
however, they are removed, it is essential that the longer set screws secure the
central abutment plate. If they are used in the two end holes they will project
into No. 1 and 4 cylinders and damage the pistons. Take care also not to lose
any of the shims which may be fitted between the abutment and plate. When
securing the abutment ensure that the distributor shaft is pressed down and
the abutment just touches the cam before tightening the bolts.
3. After removing carbon from the combustion chamber in the cylinder head
clean out the stud holes before refitting. The cylinder head has been treated
against corrosion so on no account are the stud holes to be drilled out as that
may remove the protective coating.
4. When replacing cylinder head nuts refer to page 43. The tightness of the nuts
should be checked after the engine has been thoroughly warmed and allowed
to become cold. This is important if a new gasket has been fitted.