Vaz -21213 Repair Manual page 30

Fig. 2-46. Intake valve seat profile:
I - new seat; II - reconditioned seat
Put spring A.94069/5 on tool Ä.94059, fit tapered wheel
A.94078 on spindle Ä.94069 for the exhaust valve seats or wheel
Ä.94100 for the inlet valve seats, secure the spindle in a grinder
and recut the valve seat (Fig.2-48).
The grinding wheel must be off at the moment the grinding
wheel contacts the valve seat, otherwise vibration ensued will dis-
tort the chamfer. Frequent diamond dressing of the wheel is rec-
ommended.
The working chamfer width for the exhaust valve seats should
be as shown in Fig.2-46 using tools A.94031 (20°) and A.94092
to remove the wear hardening on the minor diameter. The tools
should be used with spindle Ä.94058 and are centered with tool
Ä.94059.
The working chamfer width for the inlet valve seats should be
as shown in Fig.2-47, first machine the inner chamfer with tool
Ä.94003 (Fig.2-49) to get the diameter of 33 mm, then machine
the 20° chamfer with tool Ä.94101 to achieve the working cham-
fer width of 1.9-2 mm.
Valves. Scrape away carbon from the valves.
Check the valve stem for deformation; check the valve disc
for cracking. Always renew the damaged valve.
Examine the valve working chamfer. Reface the valve in case
of minor damages, maintaining the chamfer angle at
±5'. Note, that the distance between the bottom valve seat face
and base diameter (36 and 30.5) must be as shown in Fig.2-50.
Valve guides. Check the valve guide - to - stem clearance by
measuring the valve stem diameter and valve guide bore.
The clearance for new guides is 0.022 - 0.055 mm for the inlet
valves and 0.029 - 0.062 mm for the exhaust valves; the maxi-
mum permissible clearance (in case of wear) is 0.3 mm provided
no excessive noise is produced in the valve train.
30
Fig. 2-47. Exhaust valve seat profile:
I - new seat; II - reconditioned seat
Fig. 2-48. Regrinding the valve seat working chamfer
45°30'
Fig. 2-49. Reducing the valve seat working chamfer using the cutting tool
with spindle Ä.94058