Pelican Global Engine Runup

Описание: This single-seat taildragger is powered by a half-VW engine.
This engine was made by Global in the eighties and is based on parts of VW bug motors. Only the crankcase, head and valve cover castings are made by Global. The rest is all VW bug components that an be found easily online. It is a 2-cylinder, 4-stroke boxer that pumps 35 hp @ 3250 rpm.

There is no electrical system on this airplane. It is started by hand propping. The spark comes from a magneto keyed to the camshaft. That magneto is special in that it provides retarded spark for starting and it also spins the magneto faster as it approaches TDC so that the spark is stronger when hand propping. When the engine runs, the magneto acts normally and provides the normal timing.

In this video, I want to show how I learned to start this motor reliably.

1 ) First, I tie the tailwheel to a secure post because when it starts, the whirling propeller moves suddenly toward me. Wheel chocks might also be used but I never tried that.

2 ) Second, I prime the carb (from the cockpit) so that fuel flows into the carb float bowl and the excess flows back to the fuel tank.

3 ) Third, I have to choke this thing in a specific manner because the carb lies below the engine and it takes some work before the air-fuel mixture flows through the long intake manifold pipes and finally reaches the cylinders. So, I put full choke and full throttle but I make sure the ignition switch is OFF. I then rock the prop rapidly between compressions (10-20 times). This creates a fuel puddle inside the horizontal carb throat.

4 ) Fourth. Still with the switch OFF, I push the choke off but I leave the throttle at max opening. I then hand prop 4 to 6 times so that the rich mixture inside the carb throat is pulled up to the cylinders. Now that the mixture has reached the combustion chambers, it is ready for a spark.

5) Fifth, I put the switch ON, I set the throttle at high idle, and I set the choke at one third. I then hand prop only 1 or 2 times for the engine to start (and keep running long enough so that I can manage the idle speed and the choke until it is completely warmed up - 5 min). It works every time.

Now, the Zenith carb is reliable but primitive. It has 1 air screw for adjusting the idle mixture and 1 fuel screw to adjust the high speed mixture. At some point between idle and full throttle, there is a lean spot. Sometimes when I warm up the engine at that throttle setting, it leans out and stops running. Usually happens when I remove the choke too soon. I then have to go through the same choking and starting procedure described above to have it running again.
Also, there is no accelerator pump to squirt fuel while the throttle is advanced so the throttle has to be moved progressively from idle to full power otherwise one can feel some hesitation through the lean spot. This lean spot can be reduced to a certain extent by enriching the hi-speed and lo-speed circuits.

The one mistake to avoid: try to start this engine with full choke. Because as soon as the engine starts, it will drown immediately. No time to put the choke off. Half choke is the maximum it can take in the winter (1/3 choke in the summer).
Full choke is only used when rocking the prop before starting.

That is my experience with the Global engine. That does not apply to other engines.