17
these mounts with larger engines is not recommended. Larger
engines should use an aluminum engine mount (not furnished).
❑
1) Note that the horizontal and vertical thrust lines are scribed
into the front of the firewall. Also, notice that the vertical thrust line
is slightly off center. This is to compensate for the right thrust that
is already built into the fuselage.
a) Draw two parallel vertical lines exactly 1" on each side of
the vertical thrust line.
b) Draw two parallel horizontal lines exactly 1-13/64" above
and below the horizontal thrust line (1-13/64" is just a thin pencil
line bigger than 1-3/16").
c) The intersections of these four lines indicate where the
Blind Nuts need to be installed for the Engine Mounts. Use a 1/4"
dia. bit to drill four holes in the firewall for the 8-32 Blind Nuts.
NOTE: The 2" total vertical spacing between the blind nuts, along
with the slotted holes in the engine mounts, should allow the
engine mounts to accommodate any engine that has a crankcase
width between 1-7/16" to 1-15/16".
That should cover most
engines that will be used in the Mustang. If the width of your
engine's crankcase is less than 1-7/16", or more than 1-15/16", you
will have to plan accordingly and adjust the dimension in step 1a)
above.
❑
2) Bolt the engine mounts in place on the front of the firewall
using the 8-32 8-32 x 1-1/4" S/H Bolts, Blind Nuts, and Washers
provided. The blind nuts go on the back of the firewall, inside the
fuselage (see Building Tip in next column). As you tighten the bolts
the first time, the prongs of the blind nuts will sink into the back of
the firewall, holding the blind nuts in place. After all the blind nuts
are installed, apply a little glue on the flanges of the blind nuts
inside the fuselage, to keep the blind nuts from ever coming loose.
Be careful not to get any glue in the threads of the blind nuts.
❑
1) a) Set your engine on the engine mounts and move it
forward or backward until you measure exactly 5-3/4" from the front
of the firewall to the front face of the prop drive washer. This is the
distance your engine needs to be from the firewall for proper cowl
alignment and prop clearance purposes.
Accurately mark the
engine's mounting bolt hole locations onto the engine mounts.
Then, set the engine aside.
b) Drill the four engine mounting holes completely through the
mounts. Be very careful to drill the holes perpendicular to the
mount -- use a drill press if available. These four holes should be
clearance holes for your mounting bolts (see Safety Note below).
For example, for the Saito 1.00 engine shown here, we used
8-32 x 1-1/4" socket-head bolts. To drill a clearance hole for the
8-32 bolts, which have a diameter of .162", we used a 11/64" dia.
(.172") drill bit. A #18 drill bit (.169") would also work OK.
c) Mount your engine in place on the engine mounts.
Note: This kit DOES NOT contain bolts for mounting your engine
to the engine mounts. That's because not all .90-1.00 size engines
use the same size. Most engines will need 8-32 size bolts, while
others may need 10-32. You will need to go to the hobby shop to
obtain the correct size mounting bolts and nuts for your engine.
The bolts need to be at least 1-1/4" long.
Building Tip: Inserting the blind nuts into the holes in the back
of the firewall, working through the belly of the fuselage, can be
a difficult job if you have big hands. A short stick and a little
piece of masking tape can make the job a lot easier. Simply
double back the tape and use it to hold
the blind nut on the end of the stick as
shown (a 1/4”sq. balsa stick is being
use in these pictures). This “handle”
makes it easy to insert and hold the
blind nut in the hole while you thread
the mounting bolt in from the front.