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stonewallhayes

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I?m trying to figure out why the builder?s poh for my Lycoming O-320 has you start on the slick mag rather then the lightspeed II. It seems like it would be better to start on the electronic ignition unless I?m missing something.
 
I have an Electroair and a Slick with impulse and start using both. Never a problem.

If I were you I would give Clause a call at Lightspeed and ask if there is any reason not to use both when starting. Perhaps there was/is a set up problem that was never resolved...
 
Whatever you do, you want to start with the timing retarded to close to TDC, not advanced. With a mag, this may be accomplished with an impulse coupling, or a retard breaker/SlickStart box. For the electronic ignition, the designer will have needed to build-in a retarding mechanism or circuit. So you need to find out how your electronic system works, and in particular if it retards the timing back to zero (top dead center) or thereabouts for starting, before using it for that purpose. Failure to do this can be expensive.
 
I have a slick mag and light speed ll as well. I always start on the light speed. My mag does NOT have an impulse coupler. I broke a starter by accidentally starting on the mag first. It kicked back pretty hard and broke the starter.

You can start on the mag if you have an impulse coupler. If not, start on the lightspeed. It will retard the timing during start, especially if you have the manifold sensor hooked up.
 
stonewallhayes said:
That makes a lot of sense. Thanks! Is there any advantage to starting on both mags if my slick has an impulse coupler.
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Mostly convenience, i.e. just flip on both switches without concern for kickback. Convenience aside, there are two sparks with similar timing, so statistically the chances of ignition is higher.

The magneto's spark output is limited at impulse coupler RPM, while the EI offers full output. In general, start performance is much superior using the EI, so much so that quite a few folks install a non-impulse mag and always start using just the EI. I did so for about a year, and single EI start performance was always superior to the previous impulse-coupled mag.

The advantage is the elimination of the impulse coupler. Although the rate is low, they do fail, usually by shedding hard parts. The failure rate of an impulse coupler parked on a hangar shelf is zero.

I note you're in Anchorage. For you, maintaining an impulse coupler may be worthwhile, as it allows hand propping in the backwoods with a dead battery. Not much of a factor in my part of the world.
 
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The earlier LS II had different software. Mine is the earlier software and I start on mag to avoid kick back. I could send mine in for the updated software and it would alleviate the problem. The problem only occurs if you have a weak battery and the volts get too low. Give Lightspeed a call, they can explain.
 
DanH said:
Mostly convenience, i.e. just flip on both switches without concern for kickback. Convenience aside, there are two sparks with similar timing, so statistically the chances of ignition is higher.

The magneto's spark output is limited at impulse coupler RPM, while the EI offers full output. In general, start performance is much superior using the EI, so much so that quite a few folks install a non-impulse mag and always start using just the EI. I did so for about a year, and single EI start performance was always superior to the previous impulse-coupled mag.

The advantage is the elimination of the impulse coupler. Although the rate is low, they do fail, usually by shedding hard parts. The failure rate of an impulse coupler parked on a hangar shelf is zero.

I note you're in Anchorage. For you, maintaining an impulse coupler may be worthwhile, as it allows hand propping in the backwoods with a dead battery. Not much of a factor in my part of the world.
Click to expand...

Hey Dan, have you ever hand propped a 0-360? Mine seems to turn about 2 revolutions before it fires with the impulse mag.
 
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