Triumph TR6 PI Operation Manual page 80

ENGINE
Valve seats
9. Check valve seats for wear, pits, scores and pocketing.
Reface where necessary removing only the minimum
of material, to avoid a gas tight seal and a correctly
seating valve.
a. Correctly seating valve
b. Incorrectly seating valve
10. If it has been necessary to remove more material than
desirable, a 15° cutter may be used to reduce the
width of the seating.
CAUTION: It is important to observe that when using this
cutter the machined diameter C must not exceed 1"43
in (36'21 mm) for the inlet port seat and I '26 in
(31'23 mm) for the exhaust. Failure to heed this
precaution may render the cylinder head useless for
the fitting of valve seat inserts at a later date.
Valve seat inserts
II. Where valve seats cannot be restored by machining.
Valve seat inserts may be fitted. In instances where a
valve seat insert is already fitted and requires
renewing the old insert should be ground away until
thin enough to be cracked and levered out. Care,
however, should be used to avoid damagiIl.& the insert
pocket during this operation otherwise difficulty may
be encountered in· fitting the new insert.
12. Machine the cylinder
h~ad
to. dimensions A, Band C
given in Data. Remove burr's and swarf and carefnlly
press the insert squarely into the cylinder head.
Secure the insert
by
peening over the surrounding
cylinder head material.
13. Cut the insert seat faces at an inclusive angle of 89°
providing a chamfer of 0'040 - 0-045 in (1.016 -
1'14 mm) dimension D.
**See data page 12.29.18 Sheet 5.**
Grinding in valves
14. Use coarse followed by fine carborundum paste to
lap-in the valves. Employ the diabalo action until a
continuous narrow line is o1>tained on the valve
seating.
15. Clean off all traces of grinding compound from the
valve and seating. Smear 11 small quantity of
engineers' blue on the seating and revolve the valve
against its seating about
It!
in (6 mm) in both
directions. A good seal in indicated by a continuous
band of markihg on the valve and its seat.
16. Mter lapping-in identify each valve for reassembly to
its respective seating.
continued
12.29.18 Sheet 3
NT 2758
NT2182
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Triumph TR6 Manual. Part Nn. 545277 Issue 2