Top Flite TOPA0951 - Manual (Page 20)

20
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3. Use a Great Planes Dead Center hole locator to
mark the engine mounting bolt holes onto the mount.
❏
4. Remove the engine from the mount. Use a drill
press or a hand drill to drill #29 (or 9/64" [3.6mm])
holes at the marks. Use an 8-32 tap to cut threads all
the way through the holes—turning the tap by hand is
not necessary—you can make the job easier simply
by chucking the tap in a cordless hand drill.
If you are using
the O.S. .91
four-stroke and
wish to mount
it the same way
as shown in the
manual, reverse
the carburetor so
the throttle arm
will be on the
left side of the
engine. Then,
it will be easier
to hook up the
throttle. (For the
O.S. .95, the carb arm should be on the right side
of the engine so the needle valve will come out the
top of the cowl if side-mounting the engine.)
❏
5. Mount your engine to the mount with four 8-32 ×
1" [25mm] SHCS and #8 lock washers.
❏
6. Remove the nuts and bolts holding the engine
mount halves together. Temporarily mount the muffl er
to the engine. Hold the mount up to the fi rewall and
decide which way you are going to position the engine—
vertically, horizontally, a 45-degree angle or any other
angle around the circle inscribed on the fi rewall. Note
that the “X” marks on the fi rewall indicate the bolt hole
locations for the vertical or horizontal position. The
intersection of the horizontal and vertical lines and the
circle indicate the bolt hole locations for the 45-degree
position. The O.S. .91 four-stroke was mounted at a
45-degree angle positioning the muffl er directly under
the fuselage (this also required a #72109600 O.S.
FS70-91 Exhaust Header Pipe (OUT – OSMG2625).)
The O.S. .65AX with the included O.S. muffl er may also
be mounted at a 45-degree angle with the O.S. #744B
muffl er extension (OSMG2582). This will position the
muffl er just far enough away (1/8" [3mm]) from the
bottom of the fuselage.
The .65AX may also be mounted horizontally with a
Bisson Pitts-style muffl er (BISG4061).
The O.S. .95V was side-mounted with the O.S. M11
in-cowl 80D exhaust header pipe (OSMG2568).
❏
7. If mounting your engine in a different orientation,
make new marks around the circle inscribed on the
fi rewall where necessary. Drill precision 1/16" [1.6mm]
pilot holes at the proper marks, then enlarge the holes
with a 3/16" [4.8mm] drill.
❏
8. Use one of the 8-32 SHCS and a #8 fl at washer
to draw the 8-32 blind nuts into the back of the fi rewall
through the holes.