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TM
DEHAVILLAND BEAVER 120 ARF
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STEP 3.3 – MOUNTING YOUR EN-
GINE ON THE ENGINE MOUNTS.
Locate the two cast aluminum T-beam engine
mounts. There are four black machine screws
shipped installed in each T-beam mount and a ply-
wood spacer applied to the firewall side of each
mount.
Locate the horizontal thrust line that was factory
positioned on the front face of the forward removable
firewall. Draw a vertical thrust line up and down so
that it is centered left and right and intersects the
factory positioned horizontal thrust line at a 90 degree
angle. You will have a large plus sign or cross hair like
set of two lines when you are done.
Install your engine on the T-beam mounts. Generally
this is done using the clamp plates and positioning the
engine mounting lugs between the clamp plates and
the T-beams. Some modelers prefer to tap and drill
exact mounting holes in the T-beams to accommo-
date their particular engine.
Trial fit the T-beams and engine to the front face of
the forward removable firewall. Regardless of engine
orientation, upright, inverted, 90 degrees or any other
intermediate angle, the T-beams must be mounted to
the forward removable firewall so that that an imagi-
nary line centered through the length of the crank-
shaft would pass at a perpendicular angle through the
forward removable firewall at the intersection of the
horizontal and vertical thrust lines. Please review the
previous statements carefully before doing any drilling
or mounting of the T-beams to the forward removable
firewall. In summary… the engine crankshaft must be
centered on the forward removable firewall with no left
or right or up or down displacement. Do not worry
about thrust angles at this point… just the location.
Carefully mark the location of the firewall to T-beam
mounting bolts. Drill four holes in the firewall to
accommodate the bolts. Secure the T-beam mounts
to the forward removable firewall. The plywood
spacers are supplied to offset the engine from the
forward removable firewall when necessary for
carburetor clearances (some four strokes), fuel line
passages etc. In some cases the plywood spacers
may not be necessary and then do not have to be
used. Check the alignment again to ensure that the
center of the crankshaft lies directly in line with the
intersection of the horizontal and vertical thrust lines.
Adjust the engine in the clamps to get the intersection
right or re-drill the firewall holes if badly out of line.
Again, do not worry about thrust angles at this point…
just the location. You will work on thrust angles a bit
later.
Re-install the fuel tank mounting dowels so they protrude
from the back face of the forward removable firewall. Glue
them in place with Pacer Zap-A-Gap or Pacer 30 Minute
Zpoxy. Seal the back side and all edges of the forward
removable firewall with Pacer Zpoxy Finishing Resin or
other fuel proof sealant. Let the adhesive and finishing
resin cure thoroughly.
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STEP 3.4 – MOUNTING THE FUEL
TANK.
Temporarily join the metal tank tubes with a length of tubing
to prevent contaminants from entering the tank. Install the
fuel tank on the dowels. To do this, apply a bead of Pacer
Dap-A-Gap-A-Goo to both sides of the black sealing donut
around the neck of the tank. Apply a bead of Pacer Dap-A-
Gap-A-Goo to the top faces of each dowel. Position the
tank firmly against the firewall such that the tubes protrude
through the hole in the firewall. Push the tank firmly forward
and down onto the dowels to seat the sealant. Wrap and
secure the tank to the dowels with duct tape and then with
two or three tie wraps.
TM
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