Hobbico SUKHOI SU31 .50-.91 ARF Assembly Instructions Manual page 14

3. The engine will be mounted to the firewall on
its side (see photograph at step 7). On the firewall
there are reference marks. On the engine mount
there are also reference marks.
4. Align the reference marks of the engine mount
with the lines on the firewall and center the sides of the
engine mount with the reference lines on the firewall.
5. With the engine properly positioned mark the
engine mount holes onto the firewall. Remove the
engine from the firewall and drill through each of the
marks with a 3/16" [4.8mm] drill.
6. Position a 4mm blind nut behind one of the
holes you drilled in the firewall. Insert a 4mm [5/32"]
machine screw and washer into the hole, threading
it into the 4mm blind nut. Tighten the bolt until the
blind nut is pulled tight against the backside of the
firewall. Remove the bolt and repeat this for each of
the three remaining holes.
7. Install the engine mount to the firewall with
four 4 x 19mm [3/4"] machine screws, 4mm lock
washer and 4mm flat washer.
FUEL TANK
SILICONE
FUEL LINE
8. Assemble the fuel tank as shown. If you will be
using a fuel valve (not included) for filling the tank
rather than filling the tank by removing the line from
the carburetor, install it in the fuel line following the
instructions included with the valve.
9. Install the fuel tank into the fuselage, and
through the hole in the firewall. From the 6 x 6 x
127mm [5"] balsa stick, cut the stick to fit and glue
it in place behind the tank.
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PRESSURE
TAP TO
MUFFLER
FUEL
PIPE
TO NEEDLE
FUEL CLUNK
FIREWALL
VALVE