Mount The Engine; Install The Servos And Make The Pushrods - GREAT PLANES EXTRA 300S Instruction Manual

through the hatch cover and supports where indicated on the
plan, then remove the hatch cover and drill a 3/32" clearance
hole through the holes in the hatch cover only.

Mount the Engine

1. Cut the "spreader bar" from the supplied Great Planes
motor mount, then use a hobby knife to remove any
flashing left over from the molding process so the halves fit
together well.
2. Temporarily mount the engine mount to the firewall
with four 6-32 x 1" Phillips head machine screws and #6 flat
washers. Do not tighten the screws all the way so you can
adjust the mount.
3. Place your engine on the mount and slide the halves
in or out so the engine fits. Position the mount so the
molded-in "tick marks" are equally spaced on the horizontal
center line you drew that connects the punch marks on
both sides of the firewall. When the engine mount is
adjusted and positioned, tighten the mounting screws.
4. Position the engine on the mount so the drive washer (or
the back of the spinner) is 4-3/4" away from the firewall. Refer
to the Expert Tip that follows, then mark and drill the engine
mounting holes for the #6 x 3/4" engine mounting screws.
HOW TO ACCURATELY MARK AND DRILL THE ENGINE
MOUNTING HOLES ON THE ENGINE MOUNT
A. Use C-clamps to hold the engine in position.
B. Use a torch or a lighter to heat the end of a sharpened wire
rod and mark the center of the engine mount holes. It just
takes a little pressure of the heated rod to dimple the plastic.
C. Remove the engine, then use a pin vise or an electric
drill to start the holes with a 1/16" drill bit.
D. Remove the engine mount from the fuselage. Use a drill
press if you have one to drill the 7/64" holes, or use your
hand held electric drill to drill the holes.
Optional: Modelers who prefer to mount their engine with
machine screws instead of sheet metal screws should drill the
engine mounting holes with a #36 drill, then tap the holes with
6-32 tap. 6-32 x 3/4" Screws (not supplied) are recommended.
5. Drill a 3/16" hole for the throttle pushrod guide tube at
the suggested location indicated by the punch mark on the
front of the firewall. This location will work for most two-stroke
engines but if you are using a four-stroke engine or would like
to change the location of the throttle pushrod, plan ahead and
make sure you drill the hole so the throttle pushrod will not
interfere with the fuel tank.
Install the Servos and
Make the Pushrods
Note: The instructions and photos show the radio
installation for a two-stroke engine. If you are installing a
four-stroke engine, you may have to route the throttle
pushrod in a location other than shown in this manual and
arrange the elevator and rudder servos and pushrods
accordingly. You may still use the following instructions as a
guide and building sequence.
1. Use medium CA to glue the die-cut 1/8" plywood
servo tray to the forward fuselage top in the location
shown on the plan. Trim, then glue a die-cut 1/8" plywood
servo tray doubler across the aft rail of the servo tray. You
can see the servo tray in the photo at step 5.
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