CAMSHAFT, BALANCE SHAFT AND BEARINGS
On both the camshaft and the balance shaft, the gear
The camshaft and the balance shaft are located just
thrust load is absorbed by two thrust washers, one on
below the top of the cylinder block (Fig. 1). The
each end of the front end shaft bearings. The thrust
camshaft actuates the exhaust valve and injector
washers bear against thrust shoulders on the shafts.
A helical drive gear with a counterweight is secured to
The accurately ground cams ensure efficient, quiet cam
each shaft with a Woodruff key (Fig. 2), nut, nut
follower roller action. They are also heat treated to
retainer, retainer bolts and lock washers. The drive
provide a hard wear surface.
gears are attached to the rear end of the shafts on all
Both ends of the cam and balance shaft are supported
by bearing assemblies, each consisting of a flanged
To help maintain engine balance, a balance weight is
housing and two bushings. In addition, intermediate
installed on the front end of each shaft.
two-piece bearings support the camshaft at uniform
intervals throughout its length.
bearings are secured to the camshaft by lock rings,
thereby permitting them to be inserted into the cylinder
Advanced Timed Camshafts
block with the shaft. Each intermediate bearing is
secured in place, after the camshaft is installed, with a
Effective with four and six cylinder engines built
lock screw threaded into a counterbored hole in the top
approximately June, 1976 which require advanced
of the cylinder block.
timing in conjunction with N65 mm or larger fuel
injectors are equipped with the current camshaft which
The current engines are equipped with a low velocity,
also has the required advance timing incorporated into
low lift injector cam lobe and a long closing ramp
Fig. 1. Camshaft and Balance Shaft Assemblies