SECTION 10 – ENGINE – CHAPTER 1
10-33
Valve Inserts
Insert Oversize
Counter Bore in Cylinder Head
Insert Oversize
Exhaust valve insert
Intake valve insert
0.010 in (0.25mm)
1.739–1.740 in (44.17–44.20mm)
1.969–1.970 in (50.01–50.04mm)
0.020 in (0.58mm)
1.749–1.750 in (44.42–44.45mm)
1.979–1.980 in (50.27–50.29mm)
0.030 in (0.76mm)
1.759–1.760 in (44.68–44.70mm)
1.989–1.990 in (50.52–50.55mm)
Refacing the valve seat should always be
co–ordinated with refacing of the valve to ensure a
compression tight fit.
1. Examine the valve seat inserts and reface if
pitted, renew if loose or damaged.
2. To install a new valve insert, the cylinder head
must be counter bored, as described in the
above chart. The new insert must be chilled in dry
ice prior to installation.
Valve Seat Specifications, Figure 39.
1.
Valve seat angle
Intake
30.0
°
–30.30
°
Exhaust
45.0
°
–45.30
°
2.
Valve seat width
Intake
0.078–0.098 in
(1.9–2.4mm)
Exhaust
0.072–0.092 in (1.8–2.3mm)
3.
Valve Head Face to Cylinder Head Face Depth
Intake
0.035–0.051 in (0.89–1.29mm)
Exhaust
0.048–0.064 in (1.2–1.6mm)
NOTE: Valve inserts of 0.010 in (0.25mm) and
0.020 in (0.5mm) oversize on diameter are some-
times installed during manufacture. Cylinder Heads
with oversize inserts are stamped so10/os, so20/os,
on the exhaust manifold side in line with the valve
seat concerned.
3. Check the width of the valve seat inserts, and as
required reface by grinding to dimensions
detailed above.
TA6010013
1
2
3
39
4. Measure the concentricity of valve seats, using
a dial indicator and measure concentricity of seat
to the valve guide bore.
Total Indicator Reading should not exceed
0.002 in (0.051mm), Figure 40.
40
