Automotive vs Aviation Spark Plugs

[gasman]

Originally Posted by mike newall

We have an RV7 with a Titan IO-360 running dual P-Mags and an MT 3 blade prop.

I have conversed with, discussed with, cussed, abused, agreed and hugged Brad Dement since the mid 2000's - he is a good man and produces exquisite ignitions.

We were the second dual P-Mag install in the UK and have had no issues whatsoever since install.

They went back for a firmware update once.

We re time them every annual because it takes moments.

The plugs cost $8 a piece from O'Reilly's - good people to deal with, especially on OBT in Orlando ;-)

Oh, and there is some old gadge in the Carolinas that does other stuff for P-Mags - diddles with the timing, tells you all sorts of stuff that is super cool and useful. Likes Dragons apparently

Move up to the 21st Century and enjoy easy and simple ignition.

M

ps Bill - You can buy me a beer at Sun n Fun

How far off is the timing at that time?

I don't expect it to move at all due to the fact that there is nothing to wear out.

[mike newall]

Probably not shifted at all, but it has just become part of the annual.

We had CHT issues some while ago and it was thought that the timing may have altered, we re timed the P-Mags and the CHT's came down.

[Toobuilder]

Originally Posted by gasman

How far off is the timing at that time?

I don't expect it to move at all due to the fact that there is nothing to wear out.

This thread stated out about spark plugs, and that has been answered. But since this has turned into another Pmag review let's throw some reality on the fire...

First off, per company guidance the Pmags need to be removed at very CI so they can be inspected for wear and damage, so even the company recognizes there are things to go wrong with the moving parts. Bearings can and do wear, magnets can and do shift, and control boards can and do corrode due to water intrusion. I have personally experienced ALL of these things with my Pmags over the years. Second, I do experience timing drift between inspections despite the fact that the ignitions "pass" the subsequent bench inspection.

This reality is a significant downside of stuffing the electronics, power generation, mechanical timing, and high voltage elements in one package. Sure, it's a nice marketing niche with good consumer appeal in theory, but in practice it's an engineering hurdle that the company has strugled with for its entire history - and has yet to overcome completely. Its also one of the reasons the auto manufacturers abandoned unitized ignition decades ago in favor of maintenance free distributed system.

And as for the well documented need to "spoof" or intentionally mis-time the Pmag so that it will function on an angle valve without damage - well, there's plenty of threads and flight test data on THAT subject too.

[JimWoo50]

Originally Posted by RV6_flyer

Would be interested in learning what part number automotive plug you use without adapters.

I have 200 or so hours on my first pmag w Autolite 386 plugs and when I added second pmag 50 hrs ago went right to that plug. Been flawless so far.

[drtgraves]

Lycoming will put a pmag on one side and delete the other mag. $500 credit i believe. Then buy your own pmag

[woodmanrog]

will the Autolite 386 plugs work on an IO390 with required long reach plugs? I would really not prefer to add adapters if possible.

[sailvi767]

Something to mention. Several engine builders including Lycon strongly recommend you not mix mags with electronic ignition. As mentioned it has to do with flame front inside the cylinder since the two plugs would often fire at different times.
I know it?s done all the time but it might impact overall lifespan on a engine.

[N941WR]

Originally Posted by sailvi767

Something to mention. Several engine builders including Lycon strongly recommend you not mix mags with electronic ignition. As mentioned it has to do with flame front inside the cylinder since the two plugs would often fire at different times.
I know it’s done all the time but it might impact overall lifespan on a engine.

Lycoming now ships their IO-390's to RV-14 builders with one mag and one P-mag installed, if desired.
My guess is they might have changed their mind. I really don't know as I have not spoken to anyone at Lycoming about mixing ignition types.

[sailvi767]

Hi Bill, just to clarify I was referring to Lycon not Lycoming. EMAG also has the same recommendation to not mix ignitions. They consider it acceptable but recommend you keep them alike.
G

[airguy]

Originally Posted by sailvi767

They consider it acceptable G

Then it's OK.

Originally Posted by sailvi767

but recommend you keep them alike.
G

Because they want to sell you two units, not one. Colgate also recommends about 1/4 pound of toothpaste on your brush, three times a day.