It also uses standard ignition wiring harnesses, but there's no impulse coupling
because the system controls the ignition timing by manifold pressure and RPM.
During a 500-hour magneto inspection, the impulse coupling was discovered to have cracks in its flyweight base plate.
Impulse coupling found cracked at advance stop notches of base plate.
I had the idea it was about a 6 hp with an external magneto and an impulse coupling
and weighed about 150 pounds.
Many Continental engines are equipped with a "shower of sparks" system to multiply the number of sparks from each plug per activation of a magneto's impulse coupling. The system has been around since the Ford Model T because it works.
Magneto impulse couplings disengage at an RPM as low as 180 and Sky-Tec's starters will turn up at about 120-140 RPM--so there's not a lot of room for improvement.
The stiff/frozen bearing was causing the impulse coupling
to be ineffective.
Consider that hand propping an engine could only be possible with impulse coupling
One way of overcoming this problem is installing an impulse coupling
on at least one magneto.
Developers (including SureFly) recognized this and have pursued STCs that require the retention of the right-hand direct-drive mag (or typically the one without the impulse coupling
), while replacing the left mag with the electronic unit.
The starter, or in the case of an airplane with no electrical system, the human arm, is required to swing the propeller and crankshaft, engaging an impulse coupling
typically built into the left magneto.
While doing so will prevent the impulse coupling
from winding up and snapping, Hughes cautioned doing so could damage vanes in the engine-driven vacuum pump, especially if it's a dry pump.