P-lead support

Webb · #1 05-26-2008, 02:08 PM

I've searched the threads but can't find this.

Looking for how the p-leads have been supported when they leave the mags. It seems so flimsy to have that wire leave the mag and then be hanging out there in space just waiting to break.

Same concern for the oil temp sensor.

Any good pics out there?

Thanks,

az_gila · #2 05-26-2008, 03:09 PM

...as one option. I prefer 18 gauge shielded here, and use a soldered joint to the terminal rings and several layers of heatshrink.

Also do a good termination job on the shield. I have seen many P-lead shields just twisted and stuck in a crimp terminal, and broken after a short while....

A short wire soldered to the shield, and well supported with heat shrink, is a good technique for the shield, and is shown here in AeroElectric Bob's web site...

http://www.aeroelectric.com/articles...l/pigtail.html

At our frequencies, a ground connection of 1.5 inches or less is OK.

gil A

uk_figs · #3 05-26-2008, 06:37 PM

As a FWIW I just installed the P leads yesterday and initially twisted the shields and crimped on a connector. After sleeping on it I decided I did not like the twisted shield/crimp approach as it seemed very flimsy and prone to breakage so I did exactly what Gil suggested and did the aeroelectric solder pigtail approach for the grounds on both ends using 18awg wire and heatshrink. The result is cleaner and seems far stiffer and stronger.
Glad I did it.

Webb · #4 05-26-2008, 07:57 PM

Mine is similar with heat shrink and quite strong on the mag. What I'm wondering is how the wires are supported once they leave the mag. I've have several ideas but I'm looking for a successful installation to copy.

For instance, do you curl back to the engine support? Do you bring the 2 leads together and go the fire wall? Do you put an adel clamp somewhere and go there?

My concern is it seems there is more than just a few inches between the mags and anything to attach them to. Too much wiggle and a potential broken P-lead.

Also wondering the same for the oil temp sensor. Not as critical but would like to support it too.

szicree · #5 05-26-2008, 08:09 PM

Hi Webb,

I'm always reluctant to chime in on these type of questions because what usually comes back is a dozen people saying that the proposed method is sure to result in a smoking hole...but what I did was put an Adel clamp around the upper oil cooler hose right before it enters the engine. To this, I attached a very small Adel and passed my mag wire and oil temp wire through it and forward to the engine mount. Everything is then routed back along the mount to the firewall. YMMV.

Webb · #6 05-26-2008, 08:28 PM

Quote:

Originally Posted by szicree

Hi Webb,

I'm always reluctant to chime in on these type of questions because what usually comes back is a dozen people saying that the proposed method is sure to result in a smoking hole...but what I did was put an Adel clamp around the upper oil cooler hose right before it enters the engine. To this, I attached a very small Adel and passed my mag wire and oil temp wire through it and forward to the engine mount. Everything is then routed back along the mount to the firewall. YMMV.

Thanks Steve. I just an trying to figure out how to keep the wires from turning into wigglers and breaking later. I did think think about the oil cooler line.

uk_figs · #7 05-27-2008, 07:09 AM

For now I have mine through an adel clamp attached to the oil pressure sensor line that is clamped to the firewall. I have the oil temp sensor through there as well. I do not yet have the oil cooler hooked up so I cannot tell if this would be better but it is closer to the mag so may be a better choice.
FWIW on my Pacer the wires just run from the mags to a clamp on the firewall.

asav8tor · #8 05-27-2008, 07:17 AM

What happens if the P-lead breaks off? The engine keeps running.

scard · #9 05-27-2008, 09:10 AM

I stabilized my P-lead to the mag case with a good old glob of red RTV. Works great, no jiggle.

Webb · #10 05-27-2008, 12:55 PM

Quote:

Originally Posted by asav8tor

What happens if the P-lead breaks off? The engine keeps running.

So true and your engine keeps running when you lose your vacum pump and gyros in IMC but I would prefer either one doesn't happen - LOL.

I'm just looking for some clean installations. As you know, most of us over-do these things but I still don't like a single wire hanging out there.