SUBSECTION 11H
ENGINE TUNE-UP
Normally, when performing a tune-up on
GENERAL
an engine in service, it is only necessary
to check the various adjustments for a
This subsection will include tune-up in-
possible change in settings. However, if
formation
including
governor
the cylinder head, governor or injectors
have been replaced or overhauled, then
tle linkage adjustments and exhaust
certain preliminary adjustments are re-
valve clearance adjustments.
quired before the engine is started.
The preliminary adjustments consist of
ENGINE TUNE-UP PROCEDURES
the first four items in the tune-up se-
quence. The procedures are the same
except that the valve clearance is great-
General
er for a cold engine.
There is no scheduled interval for per-
To tune up an engine completely, per-
forming an engine tune-up. As long as
form all of the adjustments, except the
the engine performance is satisfactory,
no tune-up should be needed. Minor ad-
valve bridge adjustment in the applicable
justments in the valve and injector oper-
tune-up sequence given below after the
engine h a s r e a c h e d n o r m a l o p e r a t i n g
ating mechanism, governor, etc. should
temperature, Since the adjustments are
only be required periodically to compen-
normally made while the engine is
sate for normal wear on parts.
stopped, it may be necessary to run the
engine between adjustments to maintain
To comply with emissions regulations, in-
normal operating temperature.
jector timing, exhaust valve clearance,
engine idle and no-load speeds, and
throttle delay or fuel modulator settings
NOTE
must be checked and adjusted, if neces-
sary,
at
50,000
miles
(80
467
km)
justed at the time the cylinder
intervals (refer to Section 5 of operators
head is installed on the engine
manual). The type of governor used de-
and, until wear occurs, no further
pends upon the engine application.
adjustment is required. When
Since each governor has different char-
wear is evident, perform a com-
acteristics, the tune-up procedure varies
plete valve bridge adjustment as
accordingly. The variable speed mechan-
outlined in Subsection 11B.
ical governor is used.
The mechanical governors are identified
Use a new valve rocker cover gasket af-
by a name plate attached to the governor
ter the tune-up is completed.
housing. The letters D.W.-L.S. stamped
on the name plate denote a double-weight
limiting
speed
governor.
A
single-weight variable speed governor
plate is stamped S.W.-V.S.
Subsection 11H