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Permalink Reply by John Austin on August 23, 2023 at 7:18am

I don't know about the latest generation of Jabiru engines, but I "think" the much older ones did not have suppressed cables.  I have a late Gen 2/early Gen 3 engine and switched to CAMit (now defunct but once manufactured a quality "clone" of the Jabiru) ignition cables which were definitely suppressed and it did help with rf interference.  Most quality cables will usually have it printed right on the cable if they are suppressed.  I think Magnecor in the UK makes quality suppressed cables for the Jabiru 3300 and have heard many good reports about them.

As far as a resistor plug, I run NGK DR9eix iridium resistor plugs and they work well and also lower rf interference , but of course they are much more expensive than regular plugs.  Iridium plugs last for 100's of hours and fire at a much lower voltage, so starting is easy and no worries about too much resistance in the plug wires and plugs themselves to inhibit firing.

John

N750A

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Permalink Reply by Stephen R. Smith on August 23, 2023 at 9:27am

Steffen, I have had two Jabiru engines and one CAMit engine. None had resister connectors at the spark plug.

My second Jabiru and the CAMit both came with Magnecor wire which is a suppression wire that works well.

I have used NGK DR9EIX which work well. For the past 1,000+ hours have been using Denso 5373 (IX27) which are also resister plugs. The Denso plugs are available here: https://www.rockauto.com/en/moreinfo.php?pk=292278

The Jabiru starts better with Iridium plugs and the gap can be much wider than with the "standard" plug. If you clean the Iridium plugs every few hundred hours they last a vary long time. I have gotten over 800 hours on a set of Iridium plugs.

Another possible source of radio interference would be the leads that run from the magnetos to the distributors. The magnetos come from the factory with solid core wire. Jabiru replaces these with resistance wire as well they should. But Jabiru charges a ridiculous amount for there magnetos.

For the past 2,000 hours I have been using Honda magnetos which I get for $44 from here: https://www.boats.net/product/honda/30500-Z1C-023

I had three magneto failures with Jabiru supplied magnetos. The Honda magnetos just always work as you would expect from Honda. Yes, if you buy the Honda magnetos, you DO need to replace the solid core leads with suppressor wire.

Steve

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Permalink Reply by John Austin on August 23, 2023 at 9:52am

Steve,

Thanks for the excellent information - I see Rock Auto has good prices on both the NGK and the Denso iridium plugs - do you think one has any advantages vs the other or no difference?

I "think" my original magnetos came from Jabiru with solid core wire, and, as I recall, I replaced them with Honda magnetos that I modified with resistor wires.   That worked great, but for some reason I got a little nervous about depending on modified magnetos - I was not comfortable digging out the original wire from the magneto and inserting and epoxying in the new wire (that's how I recall I did it).   Maybe you have a better method?  If so, it would be great if you could write up a how-to-do-it post? That would be a really handy reference in the event I or others ever had a mag failure and had to modify a Honda magneto!

So, when CAMit came along with magnetos with resistor wire, I installed those along with the CAMit distributor caps and plug wires and have had zero problems.  <sigh>, wish CAMit was still around!

John

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Permalink Reply by Stephen R. Smith on August 23, 2023 at 10:46am

Hello John,

Yes, CAMit was the real deal. I have over 1,200 hours on my CAMit with ZERO problems. Much better than my two Jabirus. I wish someone would start producing that engine again.

I think the NGK and the Denso iridium plugs are both good options. I would not twist anyone's arm to buy one or the other. The standard plug Jabiru recommends is clearly inferior and I would never go back to using them. Why?: shorter life, weaker spark, hard starting if the gap widens, wasteful.

I understand your reluctance to stray from the official solutions offered by Jabiru. That's how I felt back in 2007 when I first started flying my 601. Sadly, I learned the hard way that the "experts" don't always know what they are doing. My first engine had significant problems because of the "experts". The cowling was designed incorrectly; the oil cooler was too small; there was too much scat tube in the intake system. The firewall forward kit came from Jabiru with the engine! Why was it so wrong? Well it turns out the "experts" don't know everything after all. I finally realized this: "its my airplane and its my experiment". I have to make this work myself with the best information I can find.

I rigged my current magnetos many years back so wont claim to recall the process perfectly. Yes, I dug out the old wire, like you say. There is a electrical post in the recess which delivers the spark into the wire so one must take care not to damage it when digging out the solid core wire. I simply went to an automotive parts store and bought their best resistance wire and a box of boots/connectors for the distributor-end. I used 5-minute epoxy to glue the new wire into the magneto and attached the boot/connector. (Keep the glue off the center post!) Should a regular guy undertake this task? Depends on the guy! That's how it works with experimental aircraft. Get it wrong and you may die. Do it correctly and you may have a better solution than the "experts" would provide for you.

Experimental aircraft have a very poor safety record; right down there with crop dusters. Why? Because folks have the legal right to experiment and the results vary with the individual conducting the experiment. Some folks kill themselves; others do not. We all must strive to work within our knowledge level, which should be expanded with due caution. The risks and rewards are both quite substantial. :) Builder! Be sure you really know what you are doing. Thankfully good information is out there but it takes time to understand and acquire dependable information. It can be quite aggravating.

OK, I will climb down off my soapbox now. :)

Steve

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Permalink Reply by John Austin on August 23, 2023 at 10:57am

Your description of the mod is what I recall doing, also.  I have seen on the Jab/CAMit Engine Owners Group that Magnecor UK would lend a hollow drill the correct diameter to cut the old wire loose, but that's all I know about it.  Sure would be nice if the Honda magnetos were available without the wire already installed!

John

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Permalink Reply by John Burns on August 24, 2023 at 8:08pm

I might switch my Gen 4 over to resistor plugs at this annual just to see if it will get rid of the last bit of static in the intercom and radio.  Thanks Steffen for starting this thread and thanks to everyone else for all the information.   I took a picture of my stock GEN 4 spark plug wires today.  Not much information on them, but it looks like it might be resistor wire.  Any thoughts from the picture?

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