Engine Tune-Up
SUPPLEMENTARY GOVERNING DEVICE ADJUSTMENT
ENGINE LOAD LIMIT DEVICE
Engines with mechanical governors may be equipped with a load limit device (Fig. 1) to reduce the maximum
horsepower.
This device consists of a load limit screw threaded into a plate mounted between two adjacent rocker arm shaft brackets
and a load limit lever clamped to the injector control tube.
The load limit device is located between the No. 2 and No. 3 cylinders of a three or four cylinder engine or between the
No. 1 and No. 2 cylinders of each cylinder head on a V-type engine. However, when valve rocker covers with a breather
are used, the load limit device is installed between the No. 1 and No. 2 cylinders on in-line engines and between the No.
2 and No. 3 cylinders on V-type engines to avoid interference with the rocker cover baffles.
When properly adjusted for the maximum horsepower desired, this device limits the travel of the injector control racks
and thereby the fuel output of the injectors.
Fig. 1 - Engine Load Limit Device
Adjustment
After the engine tune-up is completed, make sure the load limit device is properly installed as shown in Fig. 1. Make
sure the counterbores in the adjusting screw plate are up. The rocker arm shaft bracket bolts which fasten the adjusting
screw plate to the brackets are tightened to 50-55 lb-ft (68-75 Nm) torque. Then adjust the load limit device, on each
cylinder head, as follows:
1.
Loosen the load limit screw lock nut and remove the screw.
2.
Loosen the load limit lever clamp bolts so the lever is free to turn on the injector rack control tube.
3.
With the screw out of the plate, adjust the load limit screw lock nut so the bottom of the lock nut is 7/8" from the
bottom of the load limit screw (Fig. 1) for the initial setting.
4.
Loosen the load limit lever clamp bolts so the lever is free to turn on the injector rack control tube.
4.
Thread the load limit screw into the adjusting screw plate until the lock nut bottoms against the top of the plate.
5.
Hold the injector rack control tube in the full-fuel position and place the load limit lever against the bottom of the
load limit screw. Then tighten the load limit lever clamp bolts.
6.
Check to ensure that the injector racks will just go into the full-fuel position -- readjust the load limit lever if
necessary.
7.
Hold the load limit screw to keep it from turning, then set the lock nut until the distance between the bottom of the
lock nut and the top of the adjusting screw plate corresponds to the dimension (or number of turns) stamped on the plate.
Each full turn of the screw equals .042", or .007" for each flat on the hexagon head.
NOTE: If the plate is not stamped, adjust the load limit screw while operating the engine on a dynamometer test
stand and note the number of turns required to obtain the desired horsepower. Then stamp the plate accordingly.
8.
Thread the load limit screw into the plate until the lock nut bottoms against the top of the plate. Be sure the nut
turns with the screw.
9
Hold the load limit screw to keep it from turning, then tighten the lock nut to secure the setting.
Page 105
