ENGINE BALANCE AND BALANCE
WEIGHTS
Description
Both rotating and reciprocating forces
are completely balanced in the engines.
The eccentric rotating masses of the
crankshaft and connecting rods are bal-
anced by counterweights on the crank-
shaft cheeks.
The reciprocating masses (the piston and
upper end of the rod) produce an unbal-
anced couple by virtue of an arrange-
ment on
the
which
crankshaft
in
Figure 11B-140. Installing Cylinder
reciprocating masses, though equal, are
Liner in Cylinder Block
not opposite.
This unbalance couple,
which tends to rock the engine from end
(81-95 Nm) torque (lubrite nut) or 65-75
to end, is balanced by an arrangement of
lb-ft (88-102 Nm) torque (castellated
rotating counterweights, mounted at the
nut).
front and rear ends of the camshaft and
balance shaft, which produces a couple
equal and opposite in magnitude.
NOTE
Con-
the
sequently
engine
will
operate
Be sure the connecting rod bolt
smoothly and in balance throughout its
entire speed range.
has not turned in the connecting
rod before torque is applied to the
nut.
Each set of weights (weights on one
shaft comprise a set) rotates in an oppo-
site direction with respect to the other.
8. Check the connecting rod side clear-
When the two weights at either end of
ance.
The clearance must be 0.006" to
the engine are in a vertical plane, their
0.012".
centrifugal forces are in the same direc-
tion and oppose the unbalance couple;
9. Install the remaining liner, piston and
when they are in a horizontal plane, the
forces of
r o d a s s e m b l i e s i n t h e s a m e m a n n e r . Use
centrifugal
these balance
hold-down clamps to hold each liner in
weights are opposite and are therefore
place.
cancelled. The front balance weights are
eccentric in a direction opposite to the
rear balance weights.
10. After all of the liners and pistons
Therefore, rota-
have
been
installed,
remove
the
tion will result in the desire couple
hold-down clamps.
effective only in a vertical plane.
11. Install new compression gaskets and
The balance weights consist of two ec-
c e n t r i c w e i g h t s a t e a c h end
water and oil seals as outlined in "Cylin-
of
the
der Head" on page 11B-14. Then install
engine.
the cylinder head and any other parts
which were removed from the engine.
The front balance weights are keyed to
the front end of the camshaft and the ba-
12. After the engine has been completely
lance
shaft (Figure 11B-141 on page
reassembled,
refer to Section 11H and
11B-92).
Balance weights are of one
refill the crankcase to the proper level
piece construction.
on the dipstick.
13. Close all of the drains and fill the
R e m o v e Front Balance Weights
c o o l i n g system.
1. Remove the balance weight cover.
14. If new parts such as piston, rings,
cylinder
liners
or
were
installed,
operate
the
engine o n t h e
run-in schedule given in this subsection.
Engine (Less Major Assemblies)
