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  #1  
Old 09-14-2017, 01:52 AM
RicoB RicoB is offline
 
Join Date: Mar 2017
Location: Glendale, CA
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Exclamation Ignition decision help. Slick/pmag

I am to the point of installing my ignition system..

At this point I have 2 slick mags, the left will have the impulse coupler. They are both new. I still need the gears for it!
My question is i am really tossing the idea of running one Pmag if i do so what side of the engine should i install the Pmag and the second question is Should I install my mag with the impulse coupler or just the regular one? My ignition is wired to have the impulse coupler on the left side as per Vans plans!.
Thanks
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  #2  
Old 09-14-2017, 03:06 AM
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mike newall mike newall is offline
 
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Sell both as new and install 2 P-Mags - finished !

If you decide to install 1, please remove the impulse as it will do nothing to assist in the starting process as the P-Mag will provide impeccable starting on its own, and you can use auto plugs with it saving even more money.

If you do take out the impulse mag, do please remember to remove the spacer ring as well.......

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  #3  
Old 09-14-2017, 03:52 AM
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bullojm1 bullojm1 is offline
 
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Hi Rico,

I'm certain opinions will vary on this question, but here's my two cents. I currently have 500 hours with a slick mag with impulse coupling on the left side (bottom plugs), and a pmag on the right side (top plugs). I decided to keep the impulse coupler so I could keep both ignitions on for starting. If you don't use an impulse coupled mag, you run the risk of kickbacks as the non-impulse coupled mag will fire before TDC. I'm a belt-and-suspenders sort of engineer and like that I get the advantage of EI with the pmag, and the utter simplicity of the slick mag.

I haven't had any in flight issues with either ignitions in the last 7 years. I did rebuild the slick mag once at 300 hours as it showed some signs of wear on some of the internal parts, and the pmag exhibited issues on a run-up at 450 hours which was fixed at the factory for free.

If I were to do it all over again, I wouldn't change a thing except to use fine-wire plugs for the mag, and install the mag plugs on the top of the cylinder to reduce the fouling.

Hope that helps out with your decision making, and feel free to reach out to me at Mike (at) RVplane (dot) com if you have further questions.
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  #4  
Old 09-14-2017, 04:48 AM
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mike newall mike newall is offline
 
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The non impulse magneto will be struggling to do anything during starting, hence the use of impulse to rapidly spin the mag to help it create fire ! The P-Mag is producing max joules at the correct timing point irrespective of engine rotation speed. It can also be set up to pause to allow a couple of blades to pass so that any unburnt fuel in the inlet manifold is ingested and prevents induction fires from a backfire or indeed, prevents a starter kickback which will damage a lightweight starter.

Impulse coupling:-

Because the magneto has low voltage output at low speed, starting an engine is more difficult. Therefore, some magnetos have an impulse coupling, a springlike mechanical linkage between the engine and magneto drive shaft which "winds up" and "lets go" at the proper moment for spinning the magneto shaft. The impulse coupling uses a spring, a hub cam with flyweights, and a shell. The hub of the magneto rotates while the drive shaft is held stationary, and the spring tension builds up. When the magneto is supposed to fire, the flyweights are released by the action of the body contacting the trigger ramp. This allows the spring to unwind giving the rotating magnet a rapid rotation and letting the magneto spin at such a speed to produce a spark.
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  #5  
Old 09-14-2017, 06:00 AM
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Brantel Brantel is offline
 
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The impuse coupling also effectively retards the timing as well for easier starting (they call it Lag), the amount of Lag varies by part number. Non-Impulse mags should be grounded during start to prevent kickbacks.

I ran with 1 Pmag and 1 Impulse Mag initially and I picked the Impulse because I thought it would offer an advantage of being able to hand prop the plane if the battery was dead. The reality is I was never going to do that because the likelyhood of finding someone with hand proping experience with the balls to hand prop an O360 on a RV7 taildragger are pretty low when you need them.

Now I run dual Pmags.

I also don't like the reports of Impulse Mag failures where the Impulse coupling blows apart and sends parts all thru the accessory case.

That being said, one could run 1 Pmag with the non-impulse coupled mag as long as you keep the non-impulse coupled mag grounded during starting. Keyswitches have a jumper for this that needs to be in place. Toggle switches require the pilot to remember to do this or install them in some way that automatically interlocks out the non-impulse mag.

1 Pmag will produce super easy starts all by itself.
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  #6  
Old 09-14-2017, 06:14 AM
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N282S N282S is offline
 
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Default get pmag/s

Exactly what Brian and Mike said.
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  #7  
Old 09-14-2017, 06:48 AM
maus92 maus92 is offline
 
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I posed a version of this question by email to the E-Mag peeps a fews days ago with no reply, so I'll try it here:

If I were to replace the impulse mag on my O-360 with a P-Mag, I know that I cannot reuse the gear that is currently installed on the impulse mag. But what gear should I use? There is a gear offered on their website, but it's unclear (at least to me) if that gear can be used for either L or R P-Mag.

I'm leaning toward replacing the L mag to reduce the potential for damage in the event of a impulse coupling failure. I doubt I that I would ever consider hand propping my airplane; it's a skill that I do not posses, and frankly I don't want to learn. That said, I'll be inspecting both, and will replace the one that requires the most work (at least that's the plan today.)

As for pre-takeoff procedure, I don't want to install additional switches to cut ship's power when testing the P-Mag internal alternator. I am planning to use the VP-X "soft" switch on my EFIS to cut power to each P-Mag - is there a problem with this strategy? Alternately, I could replace the current P-leads SPST locking toggles with guarded DPDT 3 position switches, albeit with more complex switch wiring.
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  #8  
Old 09-14-2017, 07:05 AM
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Ditch the impulse coupler. Starting performance is better using any EI.
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  #9  
Old 09-14-2017, 07:06 AM
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Brantel Brantel is offline
 
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Quote:
Originally Posted by maus92 View Post
I posed a version of this question by email to the E-Mag peeps a fews days ago with no reply, so I'll try it here:

If I were to replace the impulse mag on my O-360 with a P-Mag, I know that I cannot reuse the gear that is currently installed on the impulse mag. But what gear should I use? There is a gear offered on their website, but it's unclear (at least to me) if that gear can be used for either L or R P-Mag.

I'm leaning toward replacing the L mag to reduce the potential for damage in the event of a impulse coupling failure. I doubt I that I would ever consider hand propping my airplane; it's a skill that I do not posses, and frankly I don't want to learn. That said, I'll be inspecting both, and will replace the one that requires the most work (at least that's the plan today.)

As for pre-takeoff procedure, I don't want to install additional switches to cut ship's power when testing the P-Mag internal alternator. I am planning to use the VP-X "soft" switch on my EFIS to cut power to each P-Mag - is there a problem with this strategy? Alternately, I could replace the current P-leads SPST locking toggles with guarded DPDT 3 position switches, albeit with more complex switch wiring.
The gear you need is the same one that is on the non-impulse coupled side. EmagAir will not sell you a gear unless you purchase direct and buy it at the same time with an ignition. The current gear they sell is a certified Lycoming gear. The old gear they sold was not certified and some had issues with them.

Superior and whatever ECI is now also make and sell a gear that would work fine.

68C19622 is the Lycoming number.

The VP-X will work fine for switching power to the Pmag.
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  #10  
Old 09-14-2017, 07:37 AM
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flytoboat flytoboat is offline
 
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Quote:
Originally Posted by maus92 View Post
I posed a version of this question by email to the E-Mag peeps a fews days ago with no reply, so I'll try it here:

If I were to replace the impulse mag on my O-360 with a P-Mag, I know that I cannot reuse the gear that is currently installed on the impulse mag. But what gear should I use? There is a gear offered on their website, but it's unclear (at least to me) if that gear can be used for either L or R P-Mag.

I'm leaning toward replacing the L mag to reduce the potential for damage in the event of a impulse coupling failure. I doubt I that I would ever consider hand propping my airplane; it's a skill that I do not posses, and frankly I don't want to learn. That said, I'll be inspecting both, and will replace the one that requires the most work (at least that's the plan today.)

As for pre-takeoff procedure, I don't want to install additional switches to cut ship's power when testing the P-Mag internal alternator. I am planning to use the VP-X "soft" switch on my EFIS to cut power to each P-Mag - is there a problem with this strategy? Alternately, I could replace the current P-leads SPST locking toggles with guarded DPDT 3 position switches, albeit with more complex switch wiring.
One note: You need to be able to turn on power (12V) to the P-Mags with the P-leads grounded to enter maintenance mode.
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