Surefly install and Auto plug question

[togaflyer]

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 …..

[lr172]

Originally Posted by togaflyer

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

[lr172]

Originally Posted by togaflyer

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.

[rv8ch]

Originally Posted by togaflyer

... 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.

[togaflyer]

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.

[rv8ch]

Originally Posted by togaflyer

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.

[lr172]

Originally Posted by rv8ch

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

[togaflyer]

Larry, I thought about locktite but wondered if it would create some resistance.

[gasman]

Originally Posted by rv8ch

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.

[bruceh]

Originally Posted by lr172

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!