O.S. Engines FS81-a - Manual (Page 8)

14
It is suggested to use as heavy and rigid as possible engine mounting for highest performance and
safe running. Conventional wooden mounting beams should be of rigid hardwood and of at least
15mm or 5/8-in square section. Use at least 3.5mm steel screws, such as Allen type, with locknuts,
for bolting the engine to the bearers..
INSTALLATION
CORRECT
Top surfaces are in the same plane.
INCORRECT
Rear view Side view
Re-align the surfaces
as necessary
Opposite beam
Top surfaces are not in the
same plane.
Engine does not rest firmly.
Top surfaces are not
in the same plane.
Make sure that the mounting beams are parallel and that their
top surfaces are in the same plane.
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How to fasten the mounting screws.
Hardwood mounting beams
Radial motor mount (cast aluminum)
Tighten second nut
firmlydown onto first nut.
Tighten this nut first.
Steel washer
4mm steel nuts
4mm steel screw
Spring washer or
lock washer
15mm min.
15mm min. Hardwood such as
cherry or maple.
Spring washer
3.5mm
steel Allen screw
Make sure that these mounting beams are
accurately aligned and firmly integrated with
the airframe, reinforcing the adjacent
structure to absorb vibration. Use 3.5mm or
larger steel screws, preferably Allen type
hexagon socket head cap screws, with
washers and locknuts, for bolting the engine
to the bearers.
O.S. Radial Motor Mount
A special O.S. radial motor mount (Code
No.71905030) is available, as an optional
extra, for use where firewall type mounting is
required.