Injector Timing
Whenever an
injector has been removed and reinstalled or a new injector has been installed in an
engine, the injector must be timed and the control rack positioned.
The injector
plunger is timed by the fact that it meshes with a flat area on the internal rack gear
inside the injector body. It is also timed to the fuel control rack—a dot on the gear
that is centered between two dots on the injector control rack. Actual effective length
that the plunger moves down in its bushing is controlled by the height of the injector
follower above the injector body.
To time an
injector properly, adjust the injector follower to a definite height in relation to the
injector body (fig. 5-26).
This will vary according to the size of the injector being used. This dimension is given
in the engine tune-up section of the service manual. Current timing pin dimensions can
also be found stamped on the valve rocker cover emissions decal. Be certain that you
select the proper timing pin gauge (fig. 5-27);
otherwise, the engine will run rough and fail to perform properly under load. In addition,
continued operation of the injector set at the wrong timing height can result in engine
damage.
All the
injectors can be timed in firing-order sequence during one full revolution of the
crankshaft on all two-cycle engines. A four-cycle engine requires two revolutions of the
crankshaft. The sequence for injector timing is as follows:
1. The
governor speed control lever should be in the IDLE position. If a stop lever is provided,
secure it in the STOP position.
2. Rotate
the engine crankshaft, using an engine barring tool, until the exhaust valves are fully
depressed on the cylinder that you wish to set the injector. If a barring tool is not
available, a 3/4inch-square drive socket set with a suitable socket to fit over the
crankshaft pulley will also do.
3. Insert
the small end of the timing pin (gauge) into the hole provided in the top on the injector
body, with the flat portion of the gauge facing the injector follower.
4. Gently
push the gauge by holding the knurled stem with the thumb and forefinger towards the
follower. There should be a slight drag between the gauge and the follower.
5. If
this cannot be done, loosen the injector pushrod locknut and adjust it until the drag of
the gauge (slight feel) has been determined. old the pushrod and tighten the locknut.
Recheck the feel, and, if needed, readjust.
6. When
hot setting this adjustment, wipe off the top of the injector follower and place a clean
drop of oil on it. When properly adjusted, the gauge should just wipe off the oil film
from the follower when the slight drag is felt.
7. Time
remaining injectors in the same manner. |
