Valve Seat - Mazda MX-5 1990 Workshop Manual

EX
1_
INSPECTION I REPAIR
B
05UOBX-130
'j
o
05UOBX-131
05UOBX-132
IN
05UOBX-133
05UOBX-134
Valve Seat
1. I nspect the contact su rface of each valve seat and valve
face for the following:
(1) Roughness.
(2) Damage.
2. If necessary, resurface the valve seat with a 45° valve seat
cutter and/or resurface the valve face.
3. Apply a thin coat of Prussian blue to the valve face.
4. Inspect the valve seating by pressing the valve against the
seat.
(1) If blue does not appear 360 0 around the valve face,
re~
place the valve.
(2) If blue does not appear 360 0 around the valve seat,
resurface the seat.
5. Measure the seat contact width.
Width: 0.8-1.4mm (0.031-0.055 in)
6. Verify that the valve seating position is at the center of the
valve face.
(1) If the seating position is too high, correct the valve seat
with a 75 ° cutter and a 45 ° cutter.
(2) If the seating position is too low, correct the valve seat
with a 35° (IN)
or
15° (EX) cutter and a 45° cutter.
7. Seat the valve to the valve seat with lapping compound.
8. Inspect the sinking of the valve seat.
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