Sunbeam ALPINE I SERIES: APLINE II SERIES, Workshop Manual, Page: 64 / 413

2nd re-issue
Page 26
Exhaust
A = 1·312'/1·313' (33·33 mm./33-35 mm.).
B = 1·3155'/1·3165' (33.42 mm./33·+4 mm.).
Inlet
A= 1·56r/1·563' (39·67 mm./39·70 mm.)
B = 1 ·5655' /1 ·5665* (39·76 mm./39·78 mm.).
Fig. 30. Details of exhaust and inlet valve inserts
After recutting a seat Its refaced valve should be
inserted in the valve guide to check where the
valve seats. If the valve comes too low in the
seating a new valve should be tried. If this valve
comes too low in the recut seating a 15
°
cutter
should be used to reduce the width of the seating
as shown in Fig. 26. Occasionally It is necessary to
reduce the seating width from the bottom by
means of a 75
°
cutter. See Fig. 27.
It is important to ensure that the finished seat
width Is not greater than ·07' (1 ·8 mm.) and that
the valve seats correctly as shown in the upper
picture In Fig. 24.
After refacing valve seats the valves should be
ground In and only a little grinding should be
necessary to produce a good seating.
Figs. 28 and 29 illustrates the use of a valve seat
WSM.12-4
Section B (Engine)
cutting tool and a valve seat grinder. The later Is
preferable for facing valve seat Inserts.
EXHAUST AND INLET VALVE SEAT
INSERTS (See Fig. 30)
These inserts can only be fitted when the cylinder
head has been uniformly heated to 200
°
C. (390
°
F.).
The equipment previously described under
"VALVE GUIDES-TO RENEW", should be used.
Inserts cannot be extracted from a cold cylinder
head as they are fitted ·010' to ·032' (·25 mm. to
·81 mm.) below the combustion chamber face which
shrinks In above the 1.nserts.
To remove
Old inserts can be removed by boring out until the
insert collapses. The machine d�pth stop should be
set so that boring cannot continue beyond the
bottom face of the Insert recess In the cylinder head.
To replace
From the chassis numbers given In this section on
page 8, the Inlet valve seat bores, and the Inlet
ports Immediately behind the Inlet valve seats, are
enlarged by machining after the seats have been
fitted to the cylinder head.
If an Inlet valve seat Is changed from these chassis
numbers, It will be necessary to carefully enlarge
the inlet valve seat bore, after the Insert has been
fitted In the cylinder head, so that the bore of the
Insert blends with the already enlarged Inlet post
behind the Insert.
I. Check the valve recess diameter.
2. Select a suitable oversize valve seat Insert and
check Its outside diameter.
3. Machine the cylinder head recess diameter to
the best possible finish concentric to the valve
guide centre so that the Insert will have the
correct Interference fit (see Fig. 30).
4. Heat the cylinder head for 30 minutes from cold
In an oven maintained at a temperature of
200
°
C. (390
°
F.).