DETROIT DIESEL 53
2.0 Shop Notes
FUEL INJECTOR PLUNGERS
injector are, to a great extent, determined by the type
of plunger used. Three types to plungers are illustrated
in Fig. 4. The beginning of the injection period is
controlled by the upper helix angle, The lower helix
angle retards or advances the end of the injection
period. Therefore, it is imperative that the correct
plunger is installed whenever an injector is overhauled.
If injectors with different type plungers (and spray
tips) are mixed in an engine, erratic operation will
result and may cause serious damage to the engine or
to the equipment which it powers.
Injector plungers cannot be reworked to change the
Fig. 4 Types of lnjector Plungers
output or operating characteristics. Grinding will
destroy the hardened case and result in chipping at the
helices and seizure or scoring of the plunger.
The fuel output and the operating characteristics of an
REPLACING INJECTOR FOLLOWER SPRING
When replacing the injector follower spring (.120"
diameter wire) in a low clamp body injector built prior
to June, 1965 with a new injector follower spring
(.142 " diameter wire), it will be necessary to relocate
the timing pin holes as illustrated in Fig. 5, or grind
.022 " from the side of the injector timing gage shank,
to permit continued use of the injector timing gage.
Fig. 5 - Relocating Timing Pin Hole in Injector
REFINISHING FACE OF INJECTOR FOLLOWER
When refinishing the face of an injector follower, it is
extremely important that the distance between the
injector face and the plunger slot is not less than the
1.645 " minimum shown in Fig. 6.
If the distance between the injector face and the
plunger slot is less than 1.645 ", the height of the
follower in relation to the injector body will be altered
and proper injector timing cannot be realized.
NOTE: To ensure a sufficiently hardened surface
for rocker arm contact, do not remove more
than .010 " of metal from the injector follower
Fig. 6 - lnjector Follower