Chrysler RAM TRUCK 2500 1994 Service Manual page 826

(6) Before removing valves, remove any burrs from
valve stem lock grooves to prevent damage to the
valve guides. Identify valves to ensure installation i n
original location.
VALVE CLEANING
Clean valves thoroughly. Discard burned, warped
and cracked valves.
Remove carbon and varnish deposits from inside of
valve guides with a reliable guide cleaner.
VALVE INSPECTION
Measure valve stems for wear. I f wear exceeds
0.051 mm (0.002 inch), replace the valve.
Measure valve stem guide clearance as follows:
(a) Install Valve Guide Sleeve Tool C-3973 over
valve stem and install valve (Fig. 13). The special
sleeve places the valve at the correct height for
checking with a dial indicator.
Fig. 13 Positioning Valve with Tool C-3973
(b) Attach Dial Indicator Tool C-3339 to cylinder
head and set i t at right angle of valve stem being
measured (Fig. 14).
Fig. 14 Measuring Valve Guide Wear
(c) Move valve to and from the indicator. The to­
tal dial indicator reading should not exceed 0.432
mm (0.017 inch). Ream the guides for valves with
oversize stems i f dial indicator reading is excessive
or i f the stems are scuffed or scored.
Service valves with oversize stems are available
(Fig. 15).
Reamer O / S Valve Guide Size
0.076 mm 8.026 - 8.052 mm
(0.003 in.) (0.316-0.317 in.)
0.381
mm
8.331 - 8.357 mm
(0.015 in.) (0.328 -0.329 in.)
J9309-30
Fig. 15 Reamer Sizes
Slowly turn reamer by hand and clean guide thor­
oughly before installing new valve. Ream t h e valve
guides from standard to 0.381 mm (0.015 inch).
Use a 2 step procedure so the valve guides are
reamed true i n relation to the valve seat:
• Step 1-Ream to 0.0763 m m (0.003 inch).
• Step 2-Ream to 0.381 mm (0.015 inch).
REFACING VALVES I VALVE SEATS
The intake and exhaust valves have a 45° face an­
gle and a 44 1/2° seat angle (Fig. 16).
CONTACT
POINT
A - SEAT WIDTH - INTAKE 1.016-1.524 mm ( 0 . 0 4 0 - 0 . 0 6 0 in.)
EXHAUST 1.016-1.524 mm ( 0 . 0 4 0 - 0 . 0 6 0 in.)
B - FACE A N G L E (INTAKE & EXHAUST)
C - SEAT A N G L E (INTAKE & EXHAUST)
D - CONTACT SURFACE
J9409-80
Fig. 16 Valve Face and Seat Angles
VALWES
Inspect the remaining margin after the valves are
refaced (Fig. 17). Valves with less than 1.190 mm
(0.047 inch) margin should be discarded.