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Dual PMag Install

bkervaski

Hellloooooooo!
Testing
Ordering my dual Pmags tomorrow ... anyone have install notes, gotchas, or advice for installation on a 14 with an IO-390?
 
Options to consider (Also, I love mine)

Tom at TS Flightlines can fix you up with a MP line with taps for the mags. Also, I got some heat-indicating stickers from McMaster-Carr (170-200F in 10-degree increments) to make sure I’m properly cooling the mags. Emagair has great support and they will be happy to talk you through the install and timing process which is pretty easy. Also, Bill Repucci (EI Commander) was very generous with his advice and help.

I’m just over the state line...you are welcome to come take a look. I was a total amateur and I managed to get them working so it’s not that difficult.
 
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I use -5.6 degrees from the base map

after much testing I am using -5.6 degrees from the base map... basically this gives 20 degrees under high power sea level and 30 in typical cruise.
 
I got some heat-indicating stickers from McMaster-Carr (170-200F in 10-degree increments) to make sure I?m properly cooling the mags.

Thanks for the advice!

What are you finding with the temps?
 
temp monitoring...

I have a thermistor on one of my pmags that is displayed on my panel and the steady state temps are quite modest in the 120-170 range based on OSA. You can see the temperature recorded by the unit with the engine bridge module via wifi as well. The hottest temps are after a flight during taxi and shut down.
 
My stickers are indicating around 180-degrees which I suspect occurs after shutdown as well. The left one is getting hotter than the right. Possibly because I open the oil door after shutdown.

As another data point I am currently running mine timed at 4-degrees after TDC.
 
Just installed them this week, so easy to set the timing. Note, you don't need the diode they mention as an option. That is only if your EFIS requires 5volts. Only the older Advance Systems used 5 volts.
 
Do a search on timing P-mags.

You want to either clock them or if you time them to TDC, you need to change the configuration so they fire at 20 degrees BTC and set the max advance to around 25.2 degrees. (Less max advance for the IO-390 than what you see on a parallel valve engine seems to work really well.)

Feel free to contact me with any questions you may have.
 
Hi Bill, I think your earlier advice was to set max advance to 29.4; why the change to 25.2?

I think it might be good for my unscientific reasons: the system seem so to hunt a bit in the 26-28 setting range and I think I can feel when the ignition changes from one setting to the other..... Maybe I'm imagining it. I'm using the EngineBridge to see what it is doing.
 
Hi Bill, I think your earlier advice was to set max advance to 29.4; why the change to 25.2?

Can't speak for Bill, but I will back him here. Base 20, advancing to 25 with decreasing MP appears to be right within a mixture range of best power to around 25 LOP. I have dual maps, but mostly just run 23 fixed. Cruising at peak to 25 LOP, 29 BTDC is slower for me, with higher CHT. A trusted source finds 29 offers a small advantage when leaner, i.e. 50 LOP or further.

POSTSCRIPT: 29 BTDC with mixture at 55~65F LOP was good for about 3 knots, as compared to 23 BTDC. Note the mixture dependency...as noted previously, 29 at peak EGT offers a poor result.

the system seem so to hunt a bit in the 26-28 setting range and I think I can feel when the ignition changes from one setting to the other..... Maybe I'm imagining it. I'm using the EngineBridge to see what it is doing.

I suspect you're feeling the Power of Suggestion ;)
 
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I flew today at 10500 DA varying my advance and I thought I had better speed, lower CHT (just a bit) with around 25 too. Then I read this.... good timing. (har har).

Some advice to the unwary: don't change both PMAG at once. One at a time and the engine doesn't care.......
 
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Can't speak for Bill, but I will back him here. Base 20, advancing to 25 with decreasing MP appears to be right within a mixture range of best power to around 25 LOP. I have dual maps, but mostly just run 23 fixed. Cruising at peak to 25 LOP, 29 BTDC is slower for me, with higher CHT. A trusted source finds 29 offers a small advantage when leaner, i.e. 50 LOP or further....
Dan,

That is exactly why I have changed my recommendation for the angle valve engines.
 
Almost there!

P-Mag install going well. Alabama heat on a sunny day in an aluminum hangar not so much, I've had to stop before 11a both days this weekend.

A couple questions:

1) I have noticed a lot of pics of folks grounding their P-Mag Pin #1 to the mag's own installation stud. If I'm reading this right, the manual says not to do that as it's "not a reliable ground" because the retaining hardware is anodized aluminum. That was my original plan to ground, seemed clean and convenient. If the mag installation studs are off limits, on the IO-390, where are you guys grounding?

2) The RPM signal from Pin #6 to the G3X Touch .. had the hall sensor before, if I'm understanding all I really need to do is connect the actual G3X Touch RPM wire (from the 3-wire hall sensor connect) and I'm done, no additional ground needed.

Thanks for any help!
 
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I grounded to case bolts. On the right I went low and on the left I went high. Just backed out the 1/4 nut, put the ring terminal under a new star washer, and that did it. I don't think it matters which case bolts you pick. I wouldn't try to run wire to ground them both at the same place.

I don't know why exactly not to do it at the PMAG bolt, but perhaps uneven clamping forces can occur at the PMAG face that way? Or the ring terminal in the bolt stack there permits a change in torque over time? Either way, it was easy to pick another spot and do it.

As for the Tach, I don't remember about how to wire the RPM from a hall sensor, but I connected my pin 6 directly to the GEA24 J243 Pin 8 according to my records. I only connected one side.

Interestingly, my panel will show 2400RPM when the EngineBridge says the RPM is about 2430. I don't know why the difference. I don't know that there is a way to reconcile that with a setting somewhere even if I did put a tachometer on.
 
One caution when connecting the rpm wire to the p-mag: The wire is a shielded wire (at least it is in my Steinair harness), and you need to remove both the shielding and the insulation from the tiny inside wire before making the connection at the p-mag. Otherwise, it won?t work. Ask me how I know. :rolleyes:
 
Yes, I ran a shielded wire as well, grounded only on the Garmin side of the cable; the inner wire is the connection to the PMAG.

I wondered if I could connect the other PMAG to the other RPM connector on the GEA24 and decided not to since the system would probably show it like it was a second engine and not as a redundancy.
 
I wondered if I could connect the other PMAG to the other RPM connector on the GEA24 and decided not to since the system would probably show it like it was a second engine and not as a redundancy.

You can! Pin #8 (I think .. from memory) is RPM2, if single engine it will show the highest of the two, i.e., if one fails you still get a reading.
 
I?ve been reading about the manifold plumbing. What route did you take? Im thinking of just using some barb fittings with the silicon tubing running over the the spare spot on the sensor manifold block.
 
I’ve been reading about the manifold plumbing. What route did you take? Im thinking of just using some barb fittings with the silicon tubing running over the the spare spot on the sensor manifold block.

I did the manifold pressure plumbing this morning using the kit from Aircraft Specialty, they have it all figured out, no guessing. They send everything needed, even the small stuff, highly recommended.

I'll take some pics when it's done ... getting close! (I spend a lot of time getting wire routing the way I like it)
 
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I had a noise issue with my install. The Tach was reading way high. I put the diode in at AFS recommendation (12 v system), this helped. Ultimate cause: I use a shielded wire for the tach signal. I grounded the shield at each end. bad no-no. Cut the ground on the engine side and all was well.
 
I had a noise issue with my install. The Tach was reading way high. I put the diode in at AFS recommendation (12 v system), this helped. Ultimate cause: I use a shielded wire for the tach signal. I grounded the shield at each end. bad no-no. Cut the ground on the engine side and all was well.

Thanks! :D
 
I did the manifold pressure plumbing this morning using the kit from Aircraft Specialty, they have it all figured out, no guessing. They send everything needed, even the small stuff, highly recommended. . . .

They made up the manifold fittings/hoses for me as well. works great.
For timing, I pull off the two black hoses and plug into a autozone tee with hose to time both mags at once.
 
I did the manifold pressure plumbing this morning using the kit from Aircraft Specialty, they have it all figured out, no guessing. They send everything needed, even the small stuff, highly recommended.

I'll take some pics when it's done ... getting close! (I spend a lot of time getting wire routing the way I like it)

I've been running PMags for almost 3 years using black silicone tubing and nylon fittings (from McMaster-Carr) for the plumbing, so I'd be curious to see how your setup looks.
 
I've been running PMags for almost 3 years using black silicone tubing and nylon fittings (from McMaster-Carr) for the plumbing, so I'd be curious to see how your setup looks.


No pic at this time. Hangar is a 20 minutes away.
basically, braided hose with a straight piece in the middle with two connections for the two black hoses from the pmags.
one end of the braided hose goes to the #3 cylinder, the other goes to a firewall fitting for the manifold transducer which is on the cockpit side of the firewall.
Pretty simple installation, no idea what I paid for it.
 
Just making sure I got this right .. timing set to 20 degrees .. the tooth marked with a sharpy is TC .. between 2nd and 3rd tooth (each tooth is 2 degrees):

o5M.jpg
 
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I think it is easiest to find no 1 at TDC and put a -7 offset in the pmag settings to orient the system for our engine. TDC is found both on the flywheel and with a mark at the starter so it is located with confidence.
 
Well, glad I didn't decide to fire it up today ... appears I installed the drive gear cotter pins incorrectly.

The instructions say:

Make certain the cotter pin ends are secure and lay flat. The back wall of the accessory case will be close to the end of the shaft.

I took that to mean just make sure the cotter pin is laying flat on the top of the shaft with no excessive space.

After further review, I *think* what it means is to wrap the cotter pin around the castellated nut so none of it is above the shaft.

In either case, guess I need to pull them and re-do the cotter pins ...

... thinking it thorough, this will require re-timing them as well. Three steps forward, two steps back :p :eek:
 
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Well, glad I didn't decide to fire it up today ... appears I installed the drive gear cotter pins incorrectly.

The instructions say:

Make certain the cotter pin ends are secure and lay flat. The back wall of the accessory case will be close to the end of the shaft.

I took that to mean just make sure the cotter pin is laying flat on the top of the shaft with no excessive space.

After further review, I *think* what it means is to wrap the cotter pin around the castellated nut so none of it is above the shaft.

In either case, guess I need to pull them and re-do the cotter pins ...

... thinking it thorough, this will require re-timing them as well. Three steps forward, two steps back :p :eek:
I am not sure if this is correct. Your first take away was correct, in my opinion, as I have seen the cotter pin coming from both Lycoming and PMAG securely bent over the shaft but tightly as it has been mentioned.

Also, if you are setting your timing at TDC, then you will need to reprogram the PMAG to fire at 20 BDC instead of the standard 25 BDC which is for the O360 engines. If you have not reprogramed your PMAGs, you can set your timing at about 5 degree ATDC (about 2.5 tooth of the ring gear)
 
In re the cotter pins, your first interpretation is correct. Just make sure the tails of the cotter pins lie flat. I sent mine to Emagair a few years ago for the checkup and firmware upgrade. They replaced the older, thinner cotter pins with current cotter pin, and they bent the tails over as you've described.
 
Okay, good to go on the install! Ready to fire it up.

Everything passed the "prop pull-through" test outlined in the instructions.

Got a bit hot today, test run in the morning!

o5r.jpg
 
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I think you should review the Additional LED Signaling section at the end of the Installation Guide. To me it almost sounds like you turned the power on after you ungrounded the p-lead from reading the LED state decriptions. Do you see the LED color burst when you apply power?

I'm certainly not an expert here but just trying to follow along since I just ordered my IOX-370 with Pmags and suspect I'll be going through the same steps at some point in the future.
 
Well, fired up and everything worked as expected!

Things I noted:

* Much much much smoother idle
* Started easy, even the subsequent hot starts
* RPM drop at 1800RPM was more specific (can't think of a better description)
* Tach worked, yay! Not sure why I thought it wouldn't
* Engine seemed like a happy camper
* No surprises

Test flight tomorrow or first day I can get 4500-5000 over the field and fly circuits.
 
Successful test flight done! Dual P-Mag install complete!

4500ft
66°
#1 - 347° / 1375°
#2 - 345° / 1330°
#3 - 333° / 1355°
#4 - 346° / 1410°
Oil 190°
160kts @ 23² (70% Power)
9.3gph
 
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