Weasel

Weasel

Well Known Member
I have a love for "how things work" that began when I was little. If something is not working right I not only want to fix it but I would like to know what caused it and why it is causing the problem prior to fixing it as opposed to just trying this or that to "see" if that is the problem.

On a recent flight the engine on the -10 started running noticeably rougher.

I waited a little and it changed from intermittently rough to consistently rough.

I had several things immediately run through my mind.

The first was a slightly restricted "plugged" fuel injector. I began analyzing the data on the Dynon Skyview and noticed the EGT on Cyl #5 was about 100 deg F. higher than the average temperature on the rest of the cyl's.

However I was running LOP so if that injector was restricted I would have expected to see it running a lot cooler than the rest of them but it was not.:confused:

So the next step was to think about the ignition.

I switched from BOTH (magneto and Lightspeed) to Mag.

When I did this the engine ran rougher and the EGT for #5 started dropping like a rock. Ahah. Switched to Lightspeed and the roughness went away.

I was then sure that the problem was in the Mag, Mag Harness, or the sparkplug connected to the mag.

When I got home I pulled the plugs and there it was simple as pie!


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Check the other plug on that jug. Then I'd clean those six and get several hours and pull that dud plug and another for a color comparison. Dang leaded gas. Nice quick catch though.
 
Yes and think what value having an EMS and knowing what it was telling you was worth, not just in satisfaction but dollar terms.

Now some questions to ponder.

If running LOP how do you get a plug like that?

What heat range are they?

How many hours? and have you measured the resistance of them? Sub 5000 ohms please.

Well done ;)
 
Every 50 hours I would pull plugs, check them gap them and clean them if they pass the tests.

Every annual is fine if you only do 50 a year. We have ours out 4-5 times a year.
 
Unison fine wires, pull them once a year, lately that?s 100 hours but it has been as many as 250 hours, either way they look the same, scrape out the little bit of lead, check the resistance and go another year. Personally I think every 50 hours is over kill, at least it would be on my setup, I could probably go 500 hours, if it weren?t for the annual cylinder inspection I maybe would.

I?m a firm believer in leaving my airplane in its steady state as much as possible. YMMV
 
For the record. At 48hrs prior to this all plugs were cleaned, gapped, and the resistance checked. Just happens sometimes when you run this much lead through the engine. Not the first time..
 
Russ McCutcheon said:
Unison fine wires, pull them once a year, lately that?s 100 hours but it has been as many as 250 hours, either way they look the same, scrape out the little bit of lead, check the resistance and go another year. Personally I think every 50 hours is over kill, at least it would be on my setup, I could probably go 500 hours, if it weren?t for the annual cylinder inspection I maybe would.

I?m a firm believer in leaving my airplane in its steady state as much as possible. YMMV
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Russ, the unison (now Tempest) Fine Wire plugs I would agree with you. The Champoion not at all as the resistance value drifts, some a lot sooner than others. Tempest Massives need gapping just as the Champs do and for optimal performance with massives the gap seems to be on the outer limits at 100 hours some times, and 50 seems to be the go.

I wrote an aticle for the SAAA magazine and recently Aust Bonanza Society on this topic. I received an email from John Herman (big boss) from Tempest, and on opening it his words were about the artice sent to him by a customer. I thought Ohhh nook, I am about to get sued for something.

Truth was he wanted to thnak me greatly for such a great article and clearly explaining plug maintenance. I was pleasantly surprised. He agrees, and for a fine wire you can easily get long life without erosion so the gap is not the problem.

Tempest have some excellent documents on their website, none of which I wrote. :D http://www.tempestplus.com/PricesLiterature.aspx
 
RV10inOz said:
Russ, the unison (now Tempest) Fine Wire plugs I would agree with you. The Champoion not at all as the resistance value drifts, some a lot sooner than others. Tempest Massives need gapping just as the Champs do and for optimal performance with massives the gap seems to be on the outer limits at 100 hours some times, and 50 seems to be the go.

I wrote an aticle for the SAAA magazine and recently Aust Bonanza Society on this topic. I received an email from John Herman (big boss) from Tempest, and on opening it his words were about the artice sent to him by a customer. I thought Ohhh nook, I am about to get sued for something.

Truth was he wanted to thnak me greatly for such a great article and clearly explaining plug maintenance. I was pleasantly surprised. He agrees, and for a fine wire you can easily get long life without erosion so the gap is not the problem.

Tempest have some excellent documents on their website, none of which I wrote. :D http://www.tempestplus.com/PricesLiterature.aspx
Click to expand...
Ok that makes sense, my airplane had the Champion fine wire plugs when I bought it, they had 900 hours and 20 to 30 million ohms of resistance, surprised it even ran! 1300 hours on the Tempest plugs now and there still like new, 15 to 17 hundred ohms.

Never ran the mas electrode plugs, sounds like I would not want to.
 
Russ McCutcheon said:
Ok that makes sense, my airplane had the Champion fine wire plugs when I bought it, they had 900 hours and 20 to 30 million ohms of resistance, surprised it even ran! 1300 hours on the Tempest plugs now and there still like new, 15 to 17 hundred ohms.

Never ran the mas electrode plugs, sounds like I would not want to.
Click to expand...

Fine wires are good, unless you drop one:eek: but you reduce he risk by less handling.

It is an interesting debate, one that never ends...... :D
 
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