(2) Attach Dial Indicator Tool C-3339 to cylinder
head and set it at right angle of valve stem being
measured (Fig. 18).
(3) Move valve to and from the indicator. The total
dial indicator reading should not exceed 0.432 mm
(0.017 inch). Ream the guides for valves with over-
size stems if dial indicator reading is excessive or if
the stems are scuffed or scored.
Service valves with oversize stems are available as
shown below.
Slowly turn reamer by hand and clean guide thor-
oughly before installing new valve. Ream the valve
guides from standard to 0.381 mm (0.015 inch).
Use a 2 step procedure so the valve guides are
reamed true in relation to the valve seat:
• Step 1—Ream to 0.0763 mm (0.003 inch).
• Step 2—Ream to 0.381 mm (0.015 inch).
REFACING VALVES AND VALVE SEATS
The intake and exhaust valves have a 43-1/4° to
43-3/4° face angle and a 44-1/4° to 44-3/4° seat angle
(Fig. 19).
VALVES
Inspect the remaining margin after the valves are
refaced (Fig. 20). Valves with less than 1.190 mm
(0.047 inch) margin should be discarded.
VALVE SEATS
CAUTION: DO NOT un-shroud valves during valve
seat refacing (Fig. 21).
(1) When refacing valve seats, it is important that
the correct size valve guide pilot be used for reseat-
ing stones. A true and complete surface must be
obtained.
(2) Measure the concentricity of valve seat using a
dial indicator. Total runout should not exceed 0.051
mm (0.002 inch) total indicator reading.
Fig. 18 Measuring Valve Guide Wear
1 – VALVE
2 – SPECIAL TOOL C-3339
REAMER SIZES
REAMER O/S VALVE GUIDE SIZE
0.076 mm (0.003 in.) 8.026 - 8.052 mm
(0.316 - 0.317 in.)
0.381 mm (0.015 in.) 8.331 - 8.357 mm
(0.328 - 0.329 in.)
Fig. 19 Valve Face and Seat Angles
1 – CONTACT POINT
VALVE FACE AND VALVE SEAT ANGLE CHART
ITEM DESCRIPTION SPECIFICATION
A SEAT WIDTH– 1.016 - 1.524 mm
INTAKE (0.040 - 0.060 in.)
SEAT WIDTH– 1.524 - 2.032 mm
EXHAUST (0.060 - 0.080 in.)
B FACE ANGLE
(INT. and EXT.) 43
1
⁄
4
°-43
3
⁄
4
°
C SEAT ANGLE
(INT. and EXT.) 44
1
⁄
4
°-44
3
⁄
4
°
D CONTACT
SURFACE —
9 - 96 5.2L ENGINE DN
SERVICE PROCEDURES (Continued)
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