Dodge ram truck 3500 1996 Service Manual page 1120

DESCRIPTION
AMD O P E R A T I O N
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ENGINE
COiPONENTS
CYLINDER HEAD COVER
Die-cast magnesium cylinder head covers reduce
noise and provide a good sealing surface. A steel
backed silicon gasket is used with the cylinder head
cover. This gasket can be used again.
CYLINDER
HEADS
The alloy cast iron cylinder heads (Fig. 5) are held
in place by 12 bolts. The spark plugs are located i n
the peak of the wedge between the valves.
INTAKE VALVES INTAKE VALVES INTAKE VALVE
EXHAUST EXHAUST
VALVES • VALVE
J9409-1
Fig.
5 Cylinder
Head Assembly
WALWES AMD WALWE SPRINGS
The valves are arranged in-line and inclined 18°.
The rocker pivot support and the valve guides are
cast integral with the heads.
PISTON AMD CONNECTING ROD
ASSEMBLY
The pistons are elliptically turned so that the
diameter at the pin boss is less than its diameter
across the thrust face. This allows for expansion
under normal operating conditions. Under operating
temperatures, expansion forces the pin bosses away
from each other, causing the piston to assume a more
nearly round shape.
All pistons are machined to the same weight,
regardless of size, to maintain piston balance.
The piston pin rotates in the piston only and is
retained by the press interference fit of the piston
pin in the connecting rod.
The pistons have a unique dry-film lubricant coat­
ing baked onto the skirts to reduce friction. The
lubricant is particularly effective during engine
break-in, but with time, the material becomes embed­
ded into cylinder bore walls and continues to reduce
friction.
S E R V I C E P R O C E D U R E S
VALVE TIMING
(1) Turn crankshaft until the No.6 exhaust valve is
closing and No.6 intake valve is opening.
(2) Insert a 6.350 mm (1/4 inch) spacer between rocker
arm pad and 'stem tip of No.l intake valve. Allow spring
load to bleed tappet down giving in effect a solid tappet.
(3) Install a dial indicator so plunger contacts
valve spring retainer as nearly perpendicular as pos­
sible. Zero the indicator.
(4) Rotate the crankshaft clockwise (normal running
direction) until the valve has lifted 0.863 mm (0.034 inch).
The timing of the crankshaft should now read from 10°
before top dead center to 2° after top dead center. Use a
protractor as there are no timing marks on the engine.
CAUTION: DO NOT turn crankshaft any further
clockwise as valve spring might bottom and result
in serious damage.
(5) I f reading is not within specified limits:
(a) Check sprocket index marks.
(b) Inspect timing chain for wear.
(c) Check accuracy of TDC mark on timing indicator.
MEASURING TIMING CHAIN STRETCH
(1) Place a scale next to the timing chain so that
any movement of the chain may be measured.
(2) Place a torque wrench and socket over camshaft
sprocket attaching bolt. Apply torque in the direction of
crankshaft rotation to take up slack; 41 N-m (30 ft. lbs.)
torque with cylinder head installed or 20 N-m (15 ft. lbs.)
torque with cylinder head removed. With a torque applied
to the camshaft sprocket bolt, crankshaft should not be
permitted to move. It may be necessary to block the crank­
shaft to prevent rotation.
(3) Hold a scale with dimensional reading even with the
edge of a chain link. With cylinder heads installed, apply
14 N-m (30 ft. lbs.) torque in the reverse direction. With
the cylinder heads removed, apply 20 N-m (15 ft. lbs.)
torque in the reverse direction. Note the amount of chain
movement (Fig. 6).
Fig. 6 Measuring Timing Chain Wear and Stretch