Great Planes Piper J-3 Cub 60 Kit - GPMA0162 - Manual (Page 40)

D 5. Trim the aft edge of the cowl along the cut lines.
Make final adjustments with a sanding block and 150-grit
sandpaper.
D 6. Cut the openings in the cowl for the engine only. This
step requires patience, so with the engine installed, cut a
little bit, test fit and cut a little more. Remove only a little
material at a time and inspect your work frequently. Allow
approximately 1/8" clearance around the engine and
muffler for air flow and position the cowl so there is at least
1/8" clearance for the propeller.
D 7. With the cowl taped in position, drill four 3/32" holes
through the cowl and through the 1/8" plywood cowl mount
blocks. Enlarge the holes in only the cowl to 1/8".
D 8. Secure the cowl to the fuselage with four #4 x 5/8"
wood screws and washers.
D 9. Now that the exact location of the cowl has been
determined, use a template for locating the needle valve or
other holes that must be made in the cowl.
D 10. Use the template to transfer the location of the
needle valve hole or other holes to the cowl. Cut the holes.
D 11. For easier installation, you may remove a section of
cowl from behind the engine or cut a slit and use a fifth
screw (one on each side of the slit) to secure the cowl. This
will require installing additional plywood cowl mount blocks
inside the engine compartment.
D 12. If you will be installing the dummy engine, cut along
the molded outlines and remove the section of cowl that
allows the dummy engine protrude out the side.
D 13. Use 30-minute epoxy to glue 1"-wide fiberglass cloth
to all seams on the inside of the cowl. For the best glue
bond, the seams must be thoroughly sanded. If installing
the dummy engine provided with this kit, do not add the
fiberglass cloth until after the engine is installed.
D 14. Install a fueling system. We used the Great Planes
Easy Fueler™ (GPMQ4160) mounted through the balsa
bottom sheet just ahead of the firewall. A small area must be
cut out of the aft edge of the cowl to accommodate the fueler.
D 15. Remove the fuel tank and lines, engine mount, and
other accessories. Fuelproof the engine compartment.
IMPORTANT: If you are mounting your engine inverted,
and the cylinder head does not protrude outside the
cowl, hot air generated by the engine MUST be
expelled from inside the cowl or your engine will
overheat. While the bottom of the cowl does extend past
the bottom of the fuselage creating a small hot air exit, a
section of the bottom of the cowl will have to be removed to
increase this air flow. This will not be a problem for side
mounted engine installations where the cylinder head is
well outside the cowl and in the air stream.
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