Matchless 46/G3L 1946 Maintenance Manual And Instruction Book page 29

42 TO REMOVE AND REPLACE THE VALVES
Remove the cylinder head.
Rest, in turn, head of each valve on small wood block and compress springs to allow
removal of valve split collets. The collets are a taper fit in the valve spring collars and
it may be necessary to give the collar a sharp tap to release them.
Replace valves by :—
Clean valve guide bores with rag.
Smear each valve stem with engine oil.
Reverse procedure described above.
N O T E :—
A distance sleeve is fitted under the cup for the exhaust valve springs, but not
under the cup for the inlet valve springs.
It is essential that the collets are correctly located on the valve stems. It will
be observed that the collet has two grooves machined in the bore and those
two grooves must register with the two rings on the valve stem.
only one of the grooves engages the ringed valve stem, damage will almost certainly
result.
On 350 c.c. the inlet valve head is larger in diameter than the exhaust. Therefore
inlet and exhaust valves are not interchangeable and no mistake can be made
when replacing same in the cylinder head.
On 500 c.c. both valve heads are identical in dimensions but are made of different
materials. Therefore, upon removal, valves should be laid aside so that they
may be identified for re-fitting.
on top of stem above collet grooves.
43 DECARBONISATION
Need for decarbonisation depends on fuel, oil and driving conditions. It will be indicated
by a tendency to knock on hills or accelerating after rounding a corner.
Every two thousand miles is a fair average.
Generally only necessary to take off cylinder head, clean head and piston top of deposit
and grind in valves.
Every other time also remove cylinder barrel and inspect piston rings and clean out
piston ring grooves.
leakage) replace same w i t h new.
Do hot use any abrasive, such as emery cloth, to remove deposit from the top of a piston.
It is preferable to use a scraper made of soft metal.
It is usually not necessary to clean the inside of a piston and no attempt should be made
to polish the skirt.
44 VALVE GRINDING
It is advisable to grind in the valves at every decarbonisation.
Clean valve stems with very fine emery cloth, using up and down motion with cloth
held between thumb and forefinger.
Scrape off all carbon deposit that is on the valve heads.
Smear the face of each valve, in turn, with valve grinding compound and revolve the
valve on its seat in a slight forward and backward direction, at the same time, maintaining
slight pressure on the valve head to keep it on its seat.
ally raise the valve off its seat and turn it slightly, afterwards lowering the valve to the
seat and repeating the forward and backward movement.
(See Para. 41).
In case of doubt, see marking " In " or " Ex "
If rings show any black portions on their bearing faces (indicating
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If fitted so that
During this operation, occasion-