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Pmag plug wires bad

Larry DeCamp

Well Known Member
Recent thread discussed broken spring clips, 180ohm per foot and wiggle boots to diagnose. Well, I found 4 of 8 wires completely open circuit between coil and plug connectors ��
Details:
- All 4 bad wires had RUSTY spring clips on plug terminal, none broken.
- The conductor wire contacting the clips were all in tact, not broken.
- With VOM across both ends touching the black conductor wire, NO continuity.
So, where does the black conductor fail ?
Why does it fail ?
What do the rusty spring clips (plug end) tell me about what is going on ?

Cant get a response yet from Brad D. But wondering if a switch to MSD harness (more robust) is wise. Pmag is looking for 180ohm per foot. Will a different wire resistance stress the coil or cause other problem?
Would appreciate your thoughts.
 
Larry, I'm NOT an ignition guy by any stretch. But, back in the racing days, we used to use dielectric grease at the plug connectors. Before that, we'd see some rust on the connectors, ans figured that they we loose on the plugs and the spark energy would be trying to make a connection and burn. Thus rust.

Dont know about PMags, but we switched to a 8.5mm wire and that solved several 'other' issues we had. High output electronic system and some induced crossfire.

Dont know if that helps---maybe some of the ignition guys can chime in and give use their feedback.

Tom
 
More information discovered

Reading ohms with VOM on metal connectors (both ends) gives no continuity. And, with the metal plug connector off, touching the black conductor has NO continuity. But. pushing the VOM probe between the black conductor and the insulation, bingo, proper resistance per foot.
Does anyone know what is going on. I have not reached Emagair yet for input. Just put it back together ?

To Toms suggestion, I leaning heavily toward complete replacement with MSD 8.5 system. Any thoughts are appreciated.
 
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To Toms suggestion, I leaning heavily toward complete replacement with MSD 8.5 system. Any thoughts are appreciated.
I bought a complete new set from Jegs I believe. I found one wire that was very bad, and replaced the plug cap and connector, and it solved my issue. I still have all the other parts ready to go in case I get any other issues. My idea was to replace all the other wires during the 100 hour pmag inspection.
 
Reading ohms with VOM on metal connectors (both ends) gives no continuity. And, with the metal plug connector off, touching the black conductor has NO continuity. But. pushing the VOM probe between the black conductor and the insulation, bingo, proper resistance per foot.
Does anyone know what is going on. I have not reached Emagair yet for input. Just put it back together ?

To Toms suggestion, I leaning heavily toward complete replacement with MSD 8.5 system. Any thoughts are appreciated.

Typically the center conductor is left long and bent over the insulation and the terminal crimped over that. Sounds like cheap quality wire and the core of the conductor broke at the point it was bent 90* coming out of the insulator, losing conductivity. That is why shoving the probe past that bend point and into the insulation provides continuity. Suggest buying MSD or taylor wire kits this time. I have never seen the failure you describe with those wires. Not perfect by any means, but certainly strong enough to handle the bend required for installation. Better quality wires have a SS core wire with carbon around it. Cheaper wires just mash a bunch of carbon powder into a cloth matrix & sheathing. The former will give better service, though the other method typically works when sourced through high quality mfr's.

Could have been an installation error as well. The instructions are clear to not pull too much tension on the core as you crimp on the terminal. That would create a permanent stress and lead to the failure mode you experienced.

Larry
 
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Thanks LR172

Based on your input, regardless of the quality of the wire, when bending the core wire under the crimp fitting, a radius will be better than a 90degree pull down the face of insulation.

I am working with Jegs and Summit on MSD components. Pmag has a coil tower like a distributor. Does anyone know part numbers ( connector &boot) that work on Pmag ?
 
Based on your input, regardless of the quality of the wire, when bending the core wire under the crimp fitting, a radius will be better than a 90degree pull down the face of insulation.

I am working with Jegs and Summit on MSD components. Pmag has a coil tower like a distributor. Does anyone know part numbers ( connector &boot) that work on Pmag ?

I don't know, but I have seen Dan mention that the Pmag uses the Ford EDIS coil pack.
 
I'd like to make a new set of wires for my two PMAGs just to have the lengths right. I've got 165 hours on them without any problems but I suppose problems are eventually going to arise. I'd be really appreciative of a good writeup of what to buy and what tools to have to build up a set and then have the spare material on hand to make a new one when needed. Is that already posted somewhere?
 
I'd like to make a new set of wires for my two PMAGs just to have the lengths right. I've got 165 hours on them without any problems but I suppose problems are eventually going to arise. I'd be really appreciative of a good writeup of what to buy and what tools to have to build up a set and then have the spare material on hand to make a new one when needed. Is that already posted somewhere?

Just by an MSD or Taylor custom length kit (4,6 or 8 wires) and it comes with everything you need to make the cables, including a crimping die. You can select the angles on the plug end (straight, 90 or 135*) and need to choose the right package for the type of connection you have at the coil. Hopefully someone will jump in with the type used on a pmag. The kits come with good instruction for making the cables.

Jegs and summit are affordable, with a wide selection.
 
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Just by an MSD or Taylor custom length kit (4,6 or 8 wires) and it comes with everything you need to make the cables, including a crimping die. You can select the angles on the plug end (straight, 90 or 135*) and need to choose the right package for the type of connection you have at the coil. Hopefully someone will jump in with the type used on a pmag. The kits come with good instruction for making the cables.

Jegs and summit are affordable, with a wide selection.
Mine are all 90° on both the plug and the mag end. I have a parallel valve io-360, and can't say if all engines have their plugs at the same angle, but I think so.

This is the kit I bought and seems like it will work fine, but I have not yet installed it - just used one of the plug boots on the existing wire. The wire is fatter than "normal", so you will have to drill out the grommets that allow the wire to pass through the baffles.

https://www.jegs.com/i/MSD-Ignition/121/31239/10002/-1
 
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I am running the MSD 8.5mm superconductor wires on my EI (not Pmag). The 90 degree terminals have a separate crimp for the center conductor vs the insulation. It is a nice solution. I have had no issue yet. I will say, the boots glue themselves to the wire. Even doused with dielectric grease, once the boot is on there is no getting it off the wire.
 
Mine are all 90° on both the plug and the mag end. I have a parallel valve io-360, and can't say if all engines have their plugs at the same angle, but I think so.

This is the kit I bought and seems like it will work fine, but I have not yet installed it - just used one of the plug boots on the existing wire. The wire is fatter than "normal", so you will have to drill out the grommets that allow the wire to pass through the baffles.

https://www.jegs.com/i/MSD-Ignition/121/31239/10002/-1

That is a chevy SB/BB kit. Definately check the fit on the Pmag. I thought the pmag used Ford EDIS coils and not sure the Chevy style coil connectors will fit properly. I thought the EDIS coils are different.
 
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MSD Coil socket terminals don't fit Pmag

Received my MSD set with two styles of boots and terminals, not usable. Facts for reference:
The perceived failure mode of the Pmag plug terminal was 180degree conductor bend or nicked conductor. Brad was fantastic and sent new terminals same day.

MSD plug terminals are dual crimp and logically superior. However, Jegs and Summit thought the coil terminals were also dual crimp, they are not. So how is MSD an improvement ?

The Pmag coil has small brass studs in the bottom of the socket the boot covers. The MSD connector does not mate because the ID of the connector is too large.

So, one easy solution is order 8 new coil terminals from Emagair for MSD wire Set. But, whats the point ? The chain is no stronger than the weakest link whether it is a Pmag or MSD coil terminal:mad: Any suggestions ??
 
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The Pmag coil has small brass studs in the bottom of the socket the boot covers. The MSD connector does not mate because the ID of the connector is too large.

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That's disappointing. I saw that they were not dual crimp, but I didn't check the size. :(


Here's a thread with a link to the ETCO connector that Emagair said that they require. I had forgotten about this thread - I need to check the MSD connectors I have to see if they are the same as Larry got, or are the "correct" ETCO version.

https://vansairforce.net/community/showthread.php?t=146573
 
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But, whats the point ? The chain is no stronger than the weakest link whether it is a Pmag or MSD coil terminal:mad: Any suggestions ??

The point is that the Cores on the MSD wires are superior in quality. They are designed to take the 90* bends at the terminal and history has shown that they do not fail the way that your inferior wires did. It is a well engineered product and will work when installed properly. You have already proven that the Pmag supplied wires will not, assuming the crimps were done correctly. Why repeat the effort, when you already know the weakness exists.

Also, there are different quality levels on the MSD products. The set that I put on my 10 had a dual crimp terminal for both sides. I think is was the spiral core line. That said, I have installed many MSD wire sets that used the bent over core and worked very well. The key is not to pull the core tight around it's bend and apply stress where it comes out of the insulation.

Larry
 
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ETCO fit to Pmag stud ?

Thanks to all for great participation. I took the Pmag distributor terminal to the hanger today and it was surprisingly loose on the Pmag coil stud . So, how important is a forced contact . The .171 number on the ETCO web sight is in the ball park, but interference fit required is above my pay grade . Comments appreciated.
 
Final update for Pmag pilots

The bottom line, all my leads are in spec after 250 hours use. Here are lessons learned:
* The problem was my low budget multimeter . It lied and finally died, and the new $200 Fluke says all is well .
* Both plug and coil connectors (from Emagair) WILL snap securely onto the terminal. I confirmed this with the rubber boot off and connector in hand. Coil tower connections require a hard push to POP over the terminal. The rubber boot makes it hard to sense when you are twisting around through FWF obstructions. So, there is nothing inferior about Pmag wire connectors. The latest coil terminals from Brad are brass not SS. They snap on securely also.
*I was convinced that MSD was a logical upgrade and bought a set, only to find the coil connector options do not fit the Pmag as Ross Farnam warned . So I fabricated brass inserts to sit over the Pmag coil studs and SNAP like a spark plug into HEI/Spark plug style MSD DUAL crimp connectors.
* So, the unres0lved questions
* Why does MSD boast about dual crimp when one style in there wire set
is " bend 180 degree" over the wire insulator ?
* Is MSD really any better than Pmag wires when used much more than
250 hour service? Apparently the ohm meter is your friend if it tells the
truth.
 
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