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Auto plugs vs aviation

togaflyer

Well Known Member
I have this question also over in the electronic ignition forum, but I would like to here from the -10 people running auto plugs in their IO540s. I’m installing a Surefly and replacing my Bendix, so I need a new harness made. I’m looking at possibly switching to auto plugs from my Tempest fine wire. I have been told there are issues with durability and also performance at altitude with auto plugs, i.e. 10-14K feet.

Since my fine wire only have a couple hundred hours on them, unless I mess one up on the re-gapping, I should be good for at least several hundred more hours on them. But since I need to purchase a new harness, if it’s worth the change to auto plugs, I might as well do it now. Also, what auto plugs are used in the IO 540?
 
I have over a thousand hours on my 9A with IO360 flying autoplugs, most of it in cruise in the mid-teens, and have had it up to FL210 on two occasions. No issues with the plugs at all related to altitude.

I'm also running 91E10 fuel, so no lead fouling - which helps.

I do replace them at every annual, rather than try to clean/gap - they are just too cheap.
 
The six cylinder pMag in the RV-10 I built runs perfectly on NGK BR8ES auto plugs - the same as the pMag and NGK plugs in my RV-8 and the RV-8A I built. The planes all fly just fine at 17,500’.

I used to clean them, but gave up on that years ago as they are cheap to just replace each year. But the plugs I throw away look a lot better than the aircraft plugs I used to clean and reuse.

Carl
 
Autoplugs

I’ve been using NGK BR8ES in my 10 for about 5 years/700 hours. Like most I just toss them at annual. This is with a Bendix mag (G3i harness mod) on the left and a SDS CPI on the right.

I recommend getting the adapters from Ross at SDS. I’m not sure if there is a real difference or just a coincidence that I broke 2 of the 8 that I had from emag in my Glastar but have not broken any of the 12 in the -10 that I got from SDS. They look exactly alike and they might even be sourced from the same manufacturer for all I know. It’s just my experience.

I’m just about to swap the Bendix mag for an emag and I’ll continue using BR8ES plugs.
 
Got an e mail in to G3i, there is no phone number. Is there anywhere else to go for a slick cap with an auto plug set up?
 
I’ve been using NGK BR8ES in my 10 for about 5 years/700 hours. Like most I just toss them at annual. This is with a Bendix mag (G3i harness mod) on the left and a SDS CPI on the right.

I recommend getting the adapters from Ross at SDS. I’m not sure if there is a real difference or just a coincidence that I broke 2 of the 8 that I had from emag in my Glastar but have not broken any of the 12 in the -10 that I got from SDS. They look exactly alike and they might even be sourced from the same manufacturer for all I know. It’s just my experience.

I’m just about to swap the Bendix mag for an emag and I’ll continue using BR8ES plugs.

We machine our own adapters. :)
 
My take is that if you have perfectly good fine wire plugs, I'd just use them. Champion does sell a re-gapping tool and you can carefully re-gap them for .032. They will run fine as is, but you can more optimize the gap for use with the surefly. The plugs wear very well, and personally, I feel for the bottom plugs, I'd prefer to stay with a bolted on plug wire. I've had the boots get loose on the auto plugs before on my top plugs and one boot came off a couple times. My fault of course, because I should have noticed it and replaced it earlier, but, where gravity can make the plug wire fall off, I'd prefer the bolted on aviation plug with an all metal body, especially considering you already own them. If you want to swap to auto plugs in the long term, then sure, you have plenty of time to try to get a harness for doing so.

Also, a friend recently tried out the Denso TT type plugs and they wear pretty well too. You may want to check them out.
 
The six cylinder pMag in the RV-10 I built runs perfectly on NGK BR8ES auto plugs - the same as the pMag and NGK plugs in my RV-8 and the RV-8A I built. The planes all fly just fine at 17,500’.

I used to clean them, but gave up on that years ago as they are cheap to just replace each year. But the plugs I throw away look a lot better than the aircraft plugs I used to clean and reuse.

Carl

I’m the same as Carl now for about nine months. Works great! Quite a bit better than the original G3i that was previously installed.
 
My take is that if you have perfectly good fine wire plugs, I'd just use them. Champion does sell a re-gapping tool and you can carefully re-gap them for .032. They will run fine as is, but you can more optimize the gap for use with the surefly. The plugs wear very well, and personally, I feel for the bottom plugs, I'd prefer to stay with a bolted on plug wire. I've had the boots get loose on the auto plugs before on my top plugs and one boot came off a couple times. My fault of course, because I should have noticed it and replaced it earlier, but, where gravity can make the plug wire fall off, I'd prefer the bolted on aviation plug with an all metal body, especially considering you already own them. If you want to swap to auto plugs in the long term, then sure, you have plenty of time to try to get a harness for doing so.

Also, a friend recently tried out the Denso TT type plugs and they wear pretty well too. You may want to check them out.

A small pull tie around the boot will greatly reduce that issue.
 
Great info and thank you all. So since I need to go with a new harness I have contacted G3i and plan to get the auto wire kit with a Slick cap and convert over to auto plugs with the Surefly. So now I need to order some adaptors. When installing the plug adapters do you use anti seize on the adapter and the plug.
 
Early aircraft engines used auto, or more correctly tractor spark plugs. At that time there wasn’t a good boot or wire material and often the wire terminal was exposed to the weather. Also, the ignition wire was, well copper wire. As I understand it, Two things drove the evolution of aviation plugs and wires. One being weather. An exposed wet connection at the plug, especially at altitude would arc over. The other was radios. The plain wires and existing plugs generated quite a bit of EMI. Hence the shielded plug and wire arrangement still in use today. It solved the water issue with a weather tight connection, and the connection also maintained the integrity of the shielding.

IMO, modern high quality auto wires with silicone boots along with modern resistor plugs certainly are up to the task of EMC suppression and weather proofing the connection.
 
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