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of fuel line tubing. The fuel lines should be kept as short as
possible for best fuel draw, but not so short that there is danger of
them coming off in flight. Leave a little slack in the lines.
WHEN FILLING THE FUEL TANK
To fill a fuel tank with this vent arrangement, first remove the fuel
lines from the carburetor and the muffler pressure fitting. Pump the
fuel into the tank through the fuel feed line (carb line). When the
tank is full, fuel will begin to run out the vent line (muffler line). Stop
pumping when you see the fuel start to come out the vent line! Re-
connect the fuel lines and you are ready to start the engine.
COWLING
1) An opening needs to be made in the top of the cowling to clear
the engine head and allow access to the carburetor. Begin by
marking a centerline on the top of the cowl, as shown.
Then take width and length measurements off your engine and
transfer them to the top of the cowl, using the centerline as the
base reference point. The simple pattern shown in the photo was
quickly made by measuring the diameter of the engine head and
the overall length of the engine. It will serve as an undersize
starting point for removal of material.
2) Cut or grind out the material inside the lines of your pattern. Be
aware that there are no hard and fast rules for the perfect shape
for the cutout in the cowling. The best method is to “sneak up” on
final shape, trial fitting the cowling over the engine and adjusting
the cutout as often as necessary. Make sure you achieve access
to the engine’s needle valve and to the fuel line tubing at the carb.
NOTE: A Dremel
®
tool, or similar power tool, with a coarse grit
sanding drum is without a doubt the best tool to use for removing
the cowling material quickly, easily and accurately. However, if you
do not have access to such a power tool, you can cut the opening
with a drill and a hobby knife. First drill a series of almost touching
holes inside the pattern lines (1/8” dia. works well). Then use the
knife to cut through the connecting material between each hole.
Smooth the edges of the opening with the file or a sanding block.
3) When satisfied with the opening, place the cowling over the
engine and in correct position on the front of the fuselage. Mount
the propeller and spinner on the engine. Move the cowling into
correct position on the fuselage, leaving a 3/32” to 1/8” gap
between the front of the cowling and the back of the spinner, for
clearance. Tape the cowling in exact position using a low-tack tape.
4) Near the rear of the cowling are four small pre-drilled holes -
two on each side of the airplane. These holes are for the cowl
mounting screws. With the cowling in exact position, drill a 1/16"
dia. pilot hole in the fuselage side, through any one of the cowl
mounting holes. Install an M2.6 x 10mm screw into the pilot hole
and screw it in place - do not over-tighten the screw. Recheck the
overall fit of the cowling on the fuselage to make sure nothing has
shifted, and make any necessary adjustments to the tape. Then on
the opposite side of the fuselage, drill another 1/16" pilot hole
and install a screw into that hole. Repeat this process for the
remaining two cowl mounting holes. Then remove the tape.