Chrysler RAM TRUCK 2500 1994 Service Manual page 827

I - 111 8.0L ENGINE
•
INTAKE
VALVE
FACE
•STEM-
VALVE SPRING
R E T A I N E R LOCK
G R O O V E
EXHAUST
VALVE
J 9 2 0 9 - 1 2 7
Fig. 17 Intake and Exhaust Waives
VALWE SEATS
(1) When refacing valve seats, i t is important that
the correct size valve guide pilot be used for reseat­
ing stones. A true and complete surface must be ob­
tained.
(2) Measure the concentricity of valve seat using a
dial indicator. Total
r U f i o u t
should not exceed 0.038
mm (0.0015 inch) total indicator reading.
(3) Inspect the valve seat with Prussian blue to de­
termine where the valve contacts the seat. To do this,
coat valve seat LIGHTLY with Prussian blue then set
valve i n place. Rotate the valve with light pressure.
I f the blue is transferred to the center of valve face,
contact is satisfactory. I f the blue is transferred-to
the top edge of valve face, lower valve seat with a 15°
stone. I f the blue is transferred to bottom edge of
valve face raise valve seat with a 60° stone.
(4) When seat is properly positioned the width of
valve seats should be 1.016-1.524 mm (0.040-0.060
inch).
VALVE SPRING INSPECTION
Whenever valves have been removed for inspection,
reconditioning or replacement, valve springs should
be tested. As an example the compression length of
the spring to be tested is 1-5/16 inch. Turn table of
Valve Spring Tester Tool C-647 until surface is i n line
with the 1-5/16 inch mark on the threaded stud. Be
sure the zero mark is to the front (Fig. 18). Place
spring over stud on the table and lift compressing le­
ver to set tone device. Pull on torque wrench until
ping is heard. Take reading on torque wrench at this
instant. Multiply this reading by 2. This will give the
spring load at test length. Fractional measurements
are indicated on the table for finer adjustments. Re­
fer to specifications to obtain specified height and al­
lowable tensions. Discard the springs that do not
meet specifications.
SPECIAL
TOOL C-647
9209-37
Fig. 18 Testing Waive Spring for Compressed
Length with Tool C-647
INSTALLATION
(1) Make sure there are no burrs on valve stems.
(2) Coat valve stems with lubrication oil. Insert
valves into valve guides i n cylinder head.
(3) Install new seals on all valve guides (BLACK
on intake and BROWN on exhaust). Install valve
springs and valve retainers.
(4) Compress valve springs with Valve Spring
Compressor Tool MC-998772A and adapter 6716A, in­
stall locks and release tool. Tap the retainer with a
brass or heavy plastic hammer to ensure locks have
been seated.
(5) I f valves and/or seats were ground, measure
the installed height of springs. Make sure the mea­
surement is taken from bottom of spring seat i n cyl­
inder head to the bottom surface of spring retainer. I f
spacers are installed, measure from the top of spacer.
I f height is greater than 42.86 mm (1-11/16 inches),
install a 1.587 mm (1/16 inch) spacer i n head coun-
terbore. Ensure this brings spring height back to nor­
mal, 41.27 to 42.86 mm (1-5/8 to 1-11/16 inch).
VALVE STEM SHIELD / SPRING REPLACEMENT
This procedure is done with the cylinder head in­
stalled.
(1) Disconnect the negative cable from the battery.
(2) Set engine basic timing to Top Dead Center
(TDC) and remove air cleaner.
(3) Remove cylinder head covers and spark plugs.
(4) Using suitable socket and flex handle at crank­
shaft retaining bolt, turn engine so the N o . l piston is
at TDC on the compression stroke.
(5) Remove rocker arms.
(6) With air hose attached to an adapter installed
in N o . l spark plug hole, apply 620-689 kPa (90-100
psi) air pressure.