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Surefly install and Auto plug question

togaflyer

Well Known Member
Next week I will be installing a Surefly ignition, replacing a Bendix mag. I will also be building an auto plug harness from the harness kit G3i offers. I intend to run the timing fixed to start with since I have a solid performance base running on two mags for the past few years. This way I can see if any unusual flags pop up. Later I may add a manifold pressure line and switch it to allow timing advancement. But since most of my flying is at 10k and below, what I have read, your not gaining much from advancement when flying below 0k, but please correct me it this is not the case.

For an IO 54 D4A5 with 9:1 compression, it looks like the best plugs to use are either the NGK BR8ES (#3961) or the Denso IK27 (5312) iridium plugs. The KGK are yearly toss always (based on what I have read). The Denso, being iridium and twice the price, are they keep and reuse for a few years or not. Finally, what is the recommendation for the gap for each type plug. And any advise with the Surefly, the harness, and the plugs.

Thanks …..
 
But since most of my flying is at 10k and below, what I have read, your not gaining much from advancement when flying below 0k, but please correct me it this is not the case.

Thanks …..

Incorrect.

Pretty much any time you are at peak EGT or leaner, you benefit from advance greater than 25. The leaner you are, the more the additional advance is required for optimum power. Lower MAP also benefits from more advance, but much less so than mixture. At higher altitudes (well above 10K), I tend to run closer to peak with less advance. Engine power is falling off less than drag, so the higher you fly the more efficient it becomes. However, you need to richen up as you climb to maintain the same speed, but still lower GPH than lower Alt.

The 10 is quite over powered, so most seem to run LOP at cruise and if this is the case for you, proper advance can net at least 5 ktas at 10K. I don't run anywhere close to 25 at cruise and I still pick up 2-3 knots by tweaking the advance on the fly.

Larry
 
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The KGK are yearly toss always (based on what I have read).

Thanks …..

I run NGK BR8ES and DO NOT replace every year. I replace as they wear. No need to replace after 50 - 100 hours. They will last much longer than that. , just check the gap annually. Large gaps are hard on coils.
 
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... Finally, what is the recommendation for the gap for each type plug...
The Surefly manual should give you the recommendation for the spark plug gap. Most EIs say about 0.030", which is about where new NGK plugs are when they come out of the box.
 
Another plug recommended to me was the Denso 4045 plug. It is a 27 heat range, pre gapped at 31, but has a threaded screw tip. It compares to the Denso 5312 which is the iridium version and has a solid tip. Are threaded tips an issue at all.
 
Another plug recommended to me was the Denso 4045 plug. It is a 27 heat range, pre gapped at 31, but has a threaded screw tip. It compares to the Denso 5312 which is the iridium version and has a solid tip. Are threaded tips an issue at all.

Threaded tips seem to come loose. Not sure of the true impact of this. Every time I’ve used threaded tips, even squeezing the nut before installing it, they come loose. I’ve changed to the solid tips. I have found some caps that work on the threaded tips with the nut removed, but have not tried them. I bought a lot of solid tip plugs so probably won’t test the other caps for a few years.
 
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Threaded tips seem to come loose. Not sure of the true impact of this. Every time I’ve used threaded tips, even squeezing the “bush nut” before installing it, they come loose. I’ve changed to the solid tips. I have found some caps that work on the threaded tips with the nut removed, but have not tried them. I bought a lot of solid tip plugs so probably won’t test the other caps for a few years.

I pull off the tips and use a drop of red loctite. Never had them loosn that way.

Larry
 
Threaded tips seem to come loose. Not sure of the true impact of this. Every time I’ve used threaded tips, even squeezing the nut before installing it, they come loose. I’ve changed to the solid tips. I have found some caps that work on the threaded tips with the nut removed, but have not tried them. I bought a lot of solid tip plugs so probably won’t test the other caps for a few years.

Install the tip tight and then use wire crimpers to set it. Never had one back off.
 
I run NGK BR8ES and DO NOT replace every year. I replace as they wear. No need to replace after 50 - 100 hours. They will last much longer than that. , just check the gap annually. Large gaps are hard on coils.

For me, I replace all 8 NGK BR8ES plugs every year. It cost just $27 this year for 8 new plugs. They do look fine, especially the upper plugs. The lower plugs get some big lead deposits, but you can use a dental pick to remove them.

To each his own opinion!
 
Larry, I thought about locktite but wondered if it would create some resistance.

as long as you go sparingly, there is no issue. Keep it on the threads only. There is plenty of uncoated area at the base and therefore resistance in the threads is no issue if you insure that the base mating surfaces remain clean.

Remember that we are dealing with 25-35,000 volts here; It is VERY powerfull. If it can jump an .035" air gap, I wouldn't worry too much about loctite adding a few ohms.:D Heck, even your plug has a 5K ohm resistor in it. Anything that loctite would add is well within the tolerance range of that resistor

Larry
 
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Getting ready to do my Surefly mag install with an auto plug harness conversion.

Engine is an IO 540 with dual impulse mags. Replacing the right Bendix mag with the Surefly. The current Bendix mag harness (right mag) feeds the top 1,3,5 and the bottom 2,4,6 plugs.

So question is, should I install the auto plugs with the current configuration (right side top and left side bottom), or all auto plugs on top or all on bottom. Some have said put the auto plugs all on top to prevent the chance of fowling. But I m not sure if those who recommended that was running an IO 540 or they have a four cylinder with a different harness configuration.

Also, I know the spark doesn't care if it from the top or bottom as long as it’s the correct cylinder. Just want to find out what the norm is when it comes to auto plugs and harness set ups.
 
Getting ready to do my Surefly mag install with an auto plug harness conversion.

Engine is an IO 540 with dual impulse mags. Replacing the right Bendix mag with the Surefly. The current Bendix mag harness (right mag) feeds the top 1,3,5 and the bottom 2,4,6 plugs.

So question is, should I install the auto plugs with the current configuration (right side top and left side bottom), or all auto plugs on top or all on bottom. Some have said put the auto plugs all on top to prevent the chance of fowling. But I m not sure if those who recommended that was running an IO 540 or they have a four cylinder with a different harness configuration.

Also, I know the spark doesn't care if it from the top or bottom as long as it’s the correct cylinder. Just want to find out what the norm is when it comes to auto plugs and harness set ups.

I am not sure IF there is a norm.

One EI supplier says to put auto plugs on the top with their system when the other side is a mag.

Others have said mag on top plugs and EI on bottom plugs because any lead fouling can just replace the cheap plugs.
 
When you do this, is there no worry about the crush washer that comes on these? I was thinking that once you pull it off you technically should replace it because the washer has been flattened?

I run NGK BR8ES and DO NOT replace every year. I replace as they wear. No need to replace after 50 - 100 hours. They will last much longer than that. , just check the gap annually. Large gaps are hard on coils.
 
First, thank you all for the various information you provided. Helped out significantly 👍

Surefly was installed and set in the variable timing mode. I obtained the G3i auto plug harness kit and instructions and happy with the results. Tom at 3Gi was easy to work with. Since I had a TCI Bendix mag and harness set up, I purchased the Slick mag cap. For a very reasonable cost, Tom did the modification to the Slick cap for me. Even if I was replacing a Slick harness I would recommend purchasing the Slick cap and preserving the original Slick harness. I used Denso W 4045 plugs that are pre gapped to 31 thousands. I gapped the Denso plugs to 32 thousands. All auto plugs are installed in the upper cylinder location and the fine wire plugs I run were gapped to 18 thousands (TCI Bendix mag) and installed in the lower cylinder location. During my flight, engine leans much more without missing, all temps still good range, did a lean side mag test and very smooth. Did a hot start test and much easier without the hot start drama. This was a good upgrade with positive results in the RV 10.
 
When you do this, is there no worry about the crush washer that comes on these? I was thinking that once you pull it off you technically should replace it because the washer has been flattened?

No worry as long as you get them back to the proper torque. In the auto world, plugs are removed and reinstalled all the time during maintenance and diagnosing. It is not a crush washer per se, like seen in liquid environments, such as for an oil drain plug. They are NOT considered one use only.
 
I researched what was available in electronic mags and I believe they are all good products. It was almost like deciding which glass panel I wanted, Garmin, Dynon, etc. For me, Surefly was overall an easy install, other then it was some work running power from the battery to the mag. The Surefly Sim was simple to set up and it’s a set and almost forgot system. The G3i Slick auto plug harness kit also made my choice easier. I’m not an engine guy so I did not need the ability to tweak my timing etc. so the Surefly checked all my boxes for what I wanted out of the system.
 
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