Different spark patterns

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blacklarry67
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Different spark patterns

Post by blacklarry67 » Tue Jul 23, 2019 7:37 pm

So.... kinda random, but I like to learn.
Tons of knowledge from great folks on here.
I've heard of "impulse", "slick", and recently "shower of sparks" magnetos, and even more recently Pacemaker electronic ignition.
My dad ran an impulse and a slick on his old hopped up 180.
(if memory serves me right)
I have a couple questions.
Is one type of Mag and/or combination of mags more efficient... AND what spark patterns do the Pacemakers produce and/or are the spark patterns on the Pacemaker something you can toggle to personal preference?

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GMAC 76
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Re: Different spark patterns

Post by GMAC 76 » Tue Jul 23, 2019 9:50 pm

slick is a brand name not a type of mag...impulse is a mag that retards the timing to fire the engine.....shower of sparks is used in place of the impulse coupling assembly......I remember waaay back when an impulse mag was refered to as a Bendix and a straight or non impulse mag was referred to as a slick but in fact they are just 2 different brands of magnetos....the pacemaker question is way above my pay grade but someone will tell ya

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Slidin Gator
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Re: Different spark patterns

Post by Slidin Gator » Tue Jul 23, 2019 10:59 pm

Pacemaker is an electronic ignition system vs. the magneto based systems mentioned. Pacemaker is designed and sold as an Airboat system. The Aviation world does offer electronic ignition options, but they cost way to much to justify. I keep intending to write up a thread specific to installation and operation of the Pacemaker, just have not gotten to it.

Mag ignitions are fixed timing, set em and forget em. You definitely can vary your timing curve with the Pacemaker. You can adjust the curve for normal operation and also add switch inputs that change timing based on desire (such as retarding timing when hitting the engine with Nitrous). I cover some of the points in the thread below. Make particular note of the fact that this is a thread about cylinder temps. Mag spark energy varies depending on engine speed. Electronic spark energy is pretty constant and higher (voltage/energy). The long and short is that what works on mags may not work on electronic.

https://southernairboat.com/phpBB3/view ... hp?t=71997
I grew up thinking I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540, 72” NGQ. A Bob Stossel original.

blacklarry67
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Re: Different spark patterns

Post by blacklarry67 » Wed Jul 24, 2019 5:53 am

GMAC 76, SLIDING GATOR,

Thanks for the replies gentlemen, I remember exactly what you're saying about "Bendix and Straight" my dad would crank on one Mag and then turn on the other (something about kickback on the high compression 4 cylinder breaking the pin in the starter).
Once again thanks for the knowledge, I'm an old gearhead and even at 52 years old I still like to learn.

Keep up the good fight, Black.

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Slidin Gator
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Re: Different spark patterns

Post by Slidin Gator » Wed Jul 24, 2019 8:09 am

Your dad was starting on the Impulse mag. The impulse has springs, weights etc. that retards timing to about 0 degrees BTDC for start up. Once the engine speed comes up, centrifugal force takes the impulse out of play and the mag goes to the run settings, typically 25 deg BTDC.

Once running, he turned on the second mag to fire the second set of plugs. Both mags need to fire at the same time.
I grew up thinking I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540, 72” NGQ. A Bob Stossel original.

blacklarry67
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Posts: 9
Joined: Fri Jul 05, 2019 12:45 pm

Re: Different spark patterns

Post by blacklarry67 » Wed Jul 24, 2019 6:24 pm

@S.G.
Makes perfect sense now, had no idea back then.
I'm waiting around for a fellow to finish cleaning out a barn, he has an angle valve four cylinder Lycoming all apart in a couple crates can't tell for sure if it's a 170 or 200 the intake tubes are pretty big but I'll have to measure the jugs.
I've been looking on here for a complete parts list to kinda inventory everything to see how much I'm missing before I get too excited.
I know for sure that the mags are missing, that's why I'm wanting the lowdown on ignition options.
Once again I appreciate and respect the knowledge you guys offer to a stranger for free.

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