Engine Alignment; Anti-Vibration Mounts - FNM HPE Series Installation Manual

4 Engine alignment

The engine alignment with the transmission must be carried
out carefully. Depending on the type of transmission to which
the engine is coupled, it is necessary to follow different
alignment methods.
The installer of the engine in the boat is responsible for the
alignment of the engine to the transmission system. Once
finished the alignment, these must always be checked again
after the first set in motion and before delivery of the boat to
the customer.
An improper alignment leads to vibrations of the
propulsion unit that may damage parts of the engine
and transmission, as well as to affect their operation.
One of the purposes of a correct alignment of the engine it is
to eliminate all the vibrations of the propulsion system and
thereby reducing the mechanical stresses and noise.
The failure of parts of the engine and
transmission due to a bad alignment may cause
danger to the boat user.
All transmission parts with parts in motion must
be suitably protected to prevent the user's
contact with running engine.

4.1 Anti-vibration mounts

Regardless of whether it is equipped with stern drive, inverter,
water-jet propulsion unit or sail drive, the engine must rest on
some anti-vibration mounts installed directly on the side
members.
The anti-vibration mounts are made as in Figure 10:
Engine tightening nut
Stud bolt
(preferable)
Engine
support nut
Figure 10 - Anti-vibration mounts
14 – FNM® Series HPE – Installation Manual
Hex Head
Screw
(alternative)
Anti-
vibration
mount
It is always better to use stud bolts rather than screws with
hexagon head because it ensures a greater fixing duration: if
you need to loosen the support in fact, the stud bolt remains
stationary in the longitudinal member. Prevent that the screw
is removed every time ensures durability of the bond between
screw and nut.
The orientation and the number of mounts necessary to fix the
engine are indicated in the following table:
Transmission
On-line inverter stern flywheel
Angle inverter stern flywheel
V inverter (V-drive) bow flywheel
Water-jet propulsion
stern flywheel
unit
Stern drive
Mercruiser® (Z- stern flywheel
drive)
Sail drive stern flywheel
Stern drive Volvo®
stern flywheel
(Z-drive)
In some cases (stern drive engine) it is not necessary the use
of supports on the flywheel side because the engine is
connected integrally to the transmission which acts as a
support for the engine.
The nuts for supporting and clamping the engine on the
threaded pin of the anti-vibration mount must be carried out
with a torque wrench at a torque of 150 Nm (110 lb-ft).
The selection of the correct hardness and type of anti-
vibration mounts is made by the installer and it should be
made taking into account the type of boat and the stresses
that the hull will transmit to the propulsive assembly, in
addition to the weight and arrangement of the latter inside of
the boat.
The choice of mounts of incorrect size can cause
engine damage and preclude its operation.
Supports
Orientation Distribution
side
2
2
2
2
2
2
2
Flywheel
side
2
2
2
2
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