14mm Automotive Plugs in Lycomings

[revenson]

My experience after reading Paul Dye's article in Kitplanes, "Automotive Plugs in Lycomings", June 3, 2023. I also posted this as a comment online under the Kitplane article.

I’ve used PMAGS now for 13 years, always using the recommendation from the manual. However, after reading Paul’s article, the idea to use a higher torque for the adapter made sense.

So I tried it the other day with less than perfect results: I intentionally broke an old BR8ES plug at the base of the ceramic to allow plenty of room for my adapter size socket to clear this modified plug. Inserted the modified plug into the brass adapter and then torqued the adapter to 35 ft lbs. Backed out the modified plug, then inserted the real spark plug and torqued that to 16 ft lbs. This worked fine on 2 plugs.

But, on the third cylinder the adapter broke off prior to reaching 35 ft lbs. This left most of the adapter firmly in the spark plug hole. Since I was hoping to fly the next morning, this was a real disappointment. Fortunately, a local mechanic had the appropriate easy-out and was able to remove the broken adapter.

My torque wrench had not been recently calibrated, so maybe I was using too much torque. Also, my brass adapters were all 13 years old. As luck would have it, I intended to replace all adapters at next condition inspection. Regardless, my take is that while aviation plug torque may be fine for steel adapters, I think it’s too high for brass, particularly old brass.

I hope my experience may prevent someone else from having a similar problem. For me, I’m going back to the Emagair recommended method that has worked so well for 13 years.

 

[lr172]

Have not read Paul's article, but 35 ft lbs for that brass adaptor seems awefull high. There is not a lot of meat between the bottoms of the male and female threads. Most engine mfr's recommend around 18-20 ft lbs for spark plugs; It doesn't take a lot to keep them in place. I see no need to go any higher than that, especially on a thin brass adapter. Seems to be asking for trouble.

 

[Mike S]

With my SDS system the brass adapters are recommended to be torqued to 25, plugs at 19.

 

[Ironflight]

I respect everyone’s opinions on this because, quite frankly (and as we said in the article), different ignition manufacturers specify different procedures, even with the same adapters and plugs. And of course, there are different adapters - brass and steel.

What we put in the article is a method to achieve different torque values for the plugs and adapter for those who want to salute that method. It’s up to everyone to decide what torques they want to use - and yes, at the torque values we’re talking about, wrench calibration can make a big difference! This is the low end for a ft-lb wrench, and a small percentage error is a significant number of ft-lbs.

Paul

 

[Mike S]

and yes, at the torque values we’re talking about, wrench calibration can make a big difference! This is the low end for a ft-lb wrench, and a small percentage error is a significant number of ft-lbs.

Paul

Totally correct. 15 is the lowest my ft-lb unit goes.

I try to use a torque wrench with a range that puts the needed torque close to the middle.

For sparkling plugs and adapters, I use an inch pound unit, and convert the values.

I am thinking I might try one of the torque sensing units that HF sells, great excuse to buy a new tool.

https://www.harborfreight.com/38-in-drive-59-59-ft-lb-digital-torque-adapter-58705.html

 

[Tooch]

I stick to the Pmag instructions and have never had a problem.

 

[rmarshall234]

Most engine mfr's recommend around 18-20 ft lbs for spark plugs;

I must be behind the times, I thought the typical torque values were 35 ft lbs for Lycoming and 30 ft lbs for Continental. ?

 

[Northernliving]

My experience after reading Paul Dye's article in Kitplanes, "Automotive Plugs in Lycomings", June 3, 2023. I also posted this as a comment online under the Kitplane article.

I’ve used PMAGS now for 13 years, always using the recommendation from the manual. However, after reading Paul’s article, the idea to use a higher torque for the adapter made sense.

So I tried it the other day with less than perfect results: I intentionally broke an old BR8ES plug at the base of the ceramic to allow plenty of room for my adapter size socket to clear this modified plug. Inserted the modified plug into the brass adapter and then torqued the adapter to 35 ft lbs. Backed out the modified plug, then inserted the real spark plug and torqued that to 16 ft lbs. This worked fine on 2 plugs.

But, on the third cylinder the adapter broke off prior to reaching 35 ft lbs. This left most of the adapter firmly in the spark plug hole. Since I was hoping to fly the next morning, this was a real disappointment. Fortunately, a local mechanic had the appropriate easy-out and was able to remove the broken adapter.

My torque wrench had not been recently calibrated, so maybe I was using too much torque. Also, my brass adapters were all 13 years old. As luck would have it, I intended to replace all adapters at next condition inspection. Regardless, my take is that while aviation plug torque may be fine for steel adapters, I think it’s too high for brass, particularly old brass.

I hope my experience may prevent someone else from having a similar problem. For me, I’m going back to the Emagair recommended method that has worked so well for 13 years.

I ended up buying a set of Lightspeed adapters after trying the standard PMAG adapters. Light Speed Engineering's spark plug adaptors are made of high strength aluminum bronze according to their on line material. I found them to be superior compared with brass adapters that PMAG provided.

There installation/torque instructions are also quite different, and more consistent with Lycoming torque specs.

https://lightspeed-aero.com/Manuals/Plasma_CdiManual_20130317.pdf

2.4 SPARK PLUG ADAPTORS AND SPARK PLUGS
• Aircraft engines using 18mm & ½” reach spark plugs use adaptors with the same outside thread and a 14mm & ¾” reach inside thread. Use LSE high performance HP plugs, Denso spark plugs starting with a W or NGK spark plugs starting with a B in their designation.

• Aircraft engines using 18mm & 7/8” reach spark plugs use one of the following:
o LSE long reach adaptors with 12mm inside thread for Denso X27GPR-U or X24GPR-U or equivalent 12mm spark plugs.
OR
o Optionally, for high performance applications, use LSE HP-LR (long reach) adaptors with 14mm inside thread for high performance HP-LR or IKH 14mm spark plugs.

• Install adaptors in cylinder head using the supplied copper washer.
Torque to 35 - 45 ft-lbs using anti-seize compound.
• Install automotive style spark plugs with their washer. Torque to 20 ft-lbs using anti-seize compound.

* WARNING- DO NOT USE SHORT REACH ADAPTERS IN ENGINES THAT USE LONG REACH AIRCRAFT PLUGS OR VICE VERSA.

 

[bruceh]

I stick to the Pmag instructions and have never had a problem.

Same here.
At my recent annual when removing the plugs/adapters only a couple of the adapters came out with the plugs. I have found that the plugs usually come out without the adapters, then I have to remove the adapters to clean everything up. I use the nickel based anti-seize and haven't had any issues with torquing just the plugs to turn the adapter tight.

 

[rocketman1988]

Anti Seize

You may want to research anti seize and spark plugs. NGK, for example, recommends against using any...

 

[Bavafa]

For those of us that haven't read the Kitplane article, would someone please explain what is the issue with the standard 19lb torque with the sparkplug put in the adaptor and torqued at the same time?
'

 

[lr172]

I must be behind the times, I thought the typical torque values were 35 ft lbs for Lycoming and 30 ft lbs for Continental. ?

Honestly never looked at the Lyc torque spec. Most every auto engine I worked on used around 20 and I use my arm based torque wrench for plugs on my Lyc's and never had one back out. Let's say the 35 is correct. That is for a steel plug threaded into a steel thread sert. Why would we assume this same torque value applies when threading that steel plug into a thin brass adapter? Brass is NOWHERE near the strength of steel. 35 sounds like A LOT for brass though have no equipment to verify this is too much.

Major Dia of the 14mm internal is 13.96 and the minor dia of the 18mm external is 15.93. The leaves 2 mm or .078" of brass (not steel) to hold all of that torque. That is not a lot; barely more than 1/16". If the adapters were steel, I would not be concerned with 35.

 

[rongawer]

SDS Plug Adapters

I agree that 35 ft-lbs is too much for brass into aluminum.

The SDS adapters are a brass alloy construction. I recommend using the their instructions for your adapters as well:

Install plugs into adapters and slide the copper washer over the adapter. Use only a thin stripe of anti-seize compound on the plug and adapter. Do not coat the threads.

1. Thread the spark plug into the adapter
.
2. Torque the assembly into the cylinder head using the PLUG hex to 19ft./lbs.
3. Torque the ADAPTER further to 25 ft./lbs.

Note 1: If you install and torque the adapters separately, stresses will be focused at the adapter neck and can cause it to fail during installation.

Separate item is anti-seize; many plug vendors recommended against anti-seize, but that is based on folks shorting their plugs by putting too much on the threads and it getting on to the electrodes. It’s a good thing to put on your plug threads; simply be sparing with it and don’t allow it onto the the couple threads closest to the tip.

 

[rocketman1988]

Not necessarily

“…Separate item is anti-seize; many plug vendors recommended against anti-seize, but that is based on folks shorting their plugs by putting too much on the threads and it getting on to the electrodes. It’s a good thing to put on your plug threads; simply be sparing with it and don’t allow it onto the the couple threads closest to the tip...”

Not necessarily true. There are several good articles available, especially from NGK, that recommends NOT using anti seize due to over torquing the plugs. Also, the say that the plugs with shiny threads already have an anti seize built in. The go on to say that plugs with black threads do not have this feature and anti seize can be used…

 

[hpdmp3486]

Lycoming O-320-D2A in my RV9A. Confused on which adapter, long reach or short reach?

 

[RV8JD]

Lycoming O-320-D2A in my RV9A. Confused on which adapter, long reach or short reach?

According to Lycoming SI No. 1042AH, the O-320-D has short reach plugs. See page 4, Table 2 in the link below:

https://www.lycoming.com/sites/default/files/attachments/SI1042AH%20Approved%20Spark%20Plugs.pdf​

 

[rongawer]

“…Separate item is anti-seize; many plug vendors recommended against anti-seize, but that is based on folks shorting their plugs by putting too much on the threads and it getting on to the electrodes. It’s a good thing to put on your plug threads; simply be sparing with it and don’t allow it onto the the couple threads closest to the tip...”

Not necessarily true. There are several good articles available, especially from NGK, that recommends NOT using anti seize due to over torquing the plugs. Also, the say that the plugs with shiny threads already have an anti seize built in. The go on to say that plugs with black threads do not have this feature and anti seize can be used…

I hear what you're saying, and it is common to over torque lubricated threads, versus dry - generally as a result of using the "that feels about right" torque spec. This is a very common issue with lubricated versus unlubricated cadmium coated thread torque specifications, such as a standard AN bolt would have. But even the pre-coated spark plug threads that you reference will benefit from anti-seize after the first insertion.

If you use a decent torque wrench, you won't "over torque" spark plug thread with, or without, anti-seize - regardless of what the vendor or others are saying. And when I say over torque, I mean not exceeding the torque margin of the spark plug.

To prove this, I use NGK BKR8EIX spark plugs, which have a 19mm reach (the depth of threads that insert into the cylinder head). Torque the spark plug dry to 19 ft-lbs (+/-0) and then measure the break-away torque. And then apply a very thin sheen of anti-seize, reinstall to the same torque spec. Then measure the break away torque again. Dry break-away torque (20.9 ft-lbs) will actually be higher than with anti-seize (19.7 ft-lbs); this is on a cold head, but can change after many heat cycles, although still within a ft-lbs or two - well within the operational torque margin of the fastener threads, which is generally +/-10% of the torque spec. The crush washer (assuming not reused) also assists in limiting over torque.

This topic is often well over-cooked. The simple reality is that anti-seize when sparingly applied to a fastener, and then properly torqued, minimizes gauling of the threads, inhibits corrosion, and extends thread life.

 

[lr172]

Iinsertion.

If you use a decent torque wrench, you won't "over torque" spark plug thread with, or without, anti-seize - regardless of what the vendor or others are saying. And when I say over torque, I mean not exceeding the torque margin of the spark plug.

.

That is not really correct. A torque spec is given NOT to set a specific torque, but instead to establish a desired level of stretch on the fastener. It is this stretch that keeps the fastener from backing out. The engineer will convert that desired stretch to a fastening torque value with conditions on achieving that torque, as stretch can't be measured on blind fasteners and torque is easier to achieve than using a stretch gauge. Lubricant significantly changes the amount of torque required to reach any given stretch level, as do several other procedural issues. Therefore, if the OEM wants dry torque, then adding lube will result in more stretch at the specified torque. Over stretching a fastener can create numerous problems depending upon the alloy and the margin that the designer left. Sensitive parts, like thin brass, likely have a very limited margin over the spec. To be clear, the margin is all about the strain on the fastener material and not the torque itself. Torque is a means to an end and the end is material stretch.

 

[rongawer]

That is not really correct. A torque spec is given NOT to set a specific torque, but instead to establish a desired level of stretch on the fastener. It is this stretch that keeps the fastener from backing out. The engineer will convert that desired stretch to a fastening torque value with conditions on achieving that torque, as stretch can't be measured on blind fasteners and torque is easier to achieve than using a stretch gauge. Lubricant significantly changes the amount of torque required to reach any given stretch level, as do several other procedural issues. Therefore, if the OEM wants dry torque, then adding lube will result in more stretch at the specified torque. Over stretching a fastener can create numerous problems depending upon the alloy and the margin that the designer left. Sensitive parts, like thin brass, likely have a very limited margin over the spec. To be clear, the margin is all about the strain on the fastener material and not the torque itself. Torque is a means to an end and the end is material stretch.

Always fun to debate with you Larry. I presented physical data that discussed torquing specific spark plugs in specific adapters, not the theoretical concepts behind material yield strength. I'm trying to keep this simple for the average person changing their spark plugs, not slicing and dicing the minutiae of material sensitivity and stretch. Even more so, we're discussing using 19 ft-lbs of torque in a Lycoming cylinder head that has a torque spec of 30-35 ft-lbs (a SET value from Lycoming). My response is to a practical question with a practical application. You're not going to cause any stretch of the cylinder head threads at 19, or 25 ft-lbs, lubed or dry - and those are the threads I would be most concerned with, more so than the easily replaceable adapters or plugs.

Most automotive spark plug vendors pre-coat (lubricate) their plug threads. That coating is generally ablated after the first use. Proper application of anti-seize after that is fine. Torque the plug to the vendor spec as I described previously, which for most 14mm plugs is about 19 ft-lbs, and you'll be fine.

 

[rocketman1988]

Always fun to debate with you Larry. I presented physical data that discussed torquing specific spark plugs in specific adapters, not the theoretical concepts behind material yield strength. I'm trying to keep this simple for the average person changing their spark plugs, not slicing and dicing the minutiae of material sensitivity and stretch. Even more so, we're discussing using 19 ft-lbs of torque in a Lycoming cylinder head that has a torque spec of 30-35 ft-lbs (a SET value from Lycoming). My response is to a practical question with a practical application. You're not going to cause any stretch of the cylinder head threads at 19, or 25 ft-lbs, lubed or dry - and those are the threads I would be most concerned with, more so than the easily replaceable adapters or plugs.

Most automotive spark plug vendors pre-coat (lubricate) their plug threads. That coating is generally ablated after the first use. Proper application of anti-seize after that is fine. Torque the plug to the vendor spec as I described previously, which for most 14mm plugs is about 19 ft-lbs, and you'll be fine.

Sorry, I'm going to go with Larry on this. Also, those torque specs are for an 18 mm steel plug in the cylinder. There is a big difference in material properties between the steel plug threads and the brass adapter threads. Also, concerning anti seize, who do you propose listening to...the spark plug manufacturer, the adapter manufacturer, or the engine manufacturer? It would seem that there isn't a definitive consensus.

As for me, running EFII and 14mm NGK plugs, I inserted the plug in the adapter, then installed the assembly in the cylinder. I torqued the plug to around 19 ftlbs, with the adapter. Been fine for over 300 hours so far...

 

[Bavafa]

As for me, running EFII and 14mm NGK plugs, I inserted the plug in the adapter, then installed the assembly in the cylinder. I torqued the plug to around 19 ftlbs, with the adapter. Been fine for over 300 hours so far...

This is how I have been doing it and not sure if it is right or wrong but I have not had any issues with the last three RVs that I have owned, close to a 1000 hours combined together.

 

[lr172]

AEven more so, we're discussing using 19 ft-lbs of torque in a Lycoming cylinder head that has a torque spec of 30-35 ft-lbs (a SET value from Lycoming).

I am not starting a debate with you. However, this is apples and oranges. You are quoting a torque spec for an 18mm steel thread. This post is taking about 14mm brass threads. The fact that you don't seem to think there is a difference doesn't mean you should be telling everyone else that this is the spec and don't be afraid to use it. It IS NOT a general sparkplug torque. It is for 18mm steel theaded plugs into a steel thead sert. I don't know how you can just universally apply that to brass parts.

 

[rongawer]

I am not starting a debate with you. However, this is apples and oranges. You are quoting a torque spec for an 18mm steel thread. This post is taking about 14mm brass threads. The fact that you don't seem to think there is a difference doesn't mean you should be telling everyone else that this is the spec and don't be afraid to use it. It IS NOT a general sparkplug torque. It is for 18mm steel theaded plugs into a steel thead sert. I don't know how you can just universally apply that to brass parts.

It's not apples and oranges... we're discussing inserting a 14mm spark plug into a brass alloy adapter, which is then threaded into the 18mm steel threads. The 18mm steel bore is accepting the torque being applied to the 14mm spark plug through brass adapter, and then the adapter itself.

The values I provided are specific to the application; no mention of "universal" was used by me and the only generalization I offered was in regard to the ablating of initial thread coating and torque margins offered. I provided real-world values for this practical application. You can disagree, but the data is factual.

As for me, running EFII and 14mm NGK plugs, I inserted the plug in the adapter, then installed the assembly in the cylinder. I torqued the plug to around 19 ftlbs, with the adapter. Been fine for over 300 hours so far...

Your process is in line with the procedure I provided in my previous post, so yes, I agree with this - and your inferred sentiment, but with the addition that I torque the adapter AFTER torquing the plug - which protects the adapter. Torquing the adapter first, especially without the plug inserted, could distort the adapter.

I also want to add that if you remove the spark plug, even if the adapter didn't come out, you should still retorque the adapter when you reinstall the plug.

Just the same as if you were using 18mm spark plugs, the 14mm adapter still uses a crush washer between it and the cylinder head; I personally replace these crush washers at annual (or when I replace the plugs, which may not be at annual) and recommend doing so. I also use anti-seize on the adapter, as well as the plug threads....

 

[rmarshall234]

I’m not getting into the “Who has better free advice to dispense” but will say this…

The last CI I did the owner wanted me to torque the automotive plugs/adapters to something ridiculous like 15 ft lbs which I did, and then applied my “ ok that feels about right additional torque which put me at ease “. You do not want a spark plug or adapter to loose torque, those baby’s get really hot and need the torque to dispense their heat into the cylinder. Losing torque is a sure fire way to get preignition or even detonation and you likely wouldn’t even know until the damage was done.

But you all do what you want.

 

[dmattmul]

NGK 6747 BR8EIX vs NGK 2668 BKR8EIX (Short reach plugs)

After hearing and reading about multiple incidents where a Lycoming engine blew a plug and adapter off, I came to the conclusion that I wanted to be able to torque the adapter at a different value than the plug. (First torquing the plug then adapter) The Kit Planes article on this process was helpful.

I first saw the part number NGK BKR8EIX in a thread and initially thought it was a typo. It's a valid part number and has one added benefit in that it has a 16 mm Hex Size vs the non-K part number 21 mm. Gap, reach, solid terminal, thread diameter (14 mm), thread pitch, heat range, resister value, torque specs, center electrode size, materials identical. There are 2 differences 1) The center electrode is non-projected on one and projected on the other. (See pic) and 2) The ceramic body on the K version is 10.0 mm and the non-K 11.5 mm. The rubber/elastomer boot still fits tight on the 10.0 mm body but obviously not quite as tight.

Seems like a good alternative to more easily torque the adapter while clearing the hex on the spark plug. FYI the Denso plugs on my long reach angle valve 390 have the smaller hex and projected center electrode like the K version of the short reach.

PIREP on the K version? Issues?

 

[riobison]

After using junk torque wrenches I finally broke down and bought a good Snap on torque wrench. I just changed out all 4 cyls due to the ECI AD and while waiting on the cyls I bought the wrench for the project. Amazing the accuracy and repeatability of a good torque wrench.

Should have done this 50 yrs ago.

 

[rocketman1988]

After using junk torque wrenches I finally broke down and bought a good Snap on torque wrench. I just changed out all 4 cyls due to the ECI AD and while waiting on the cyls I bought the wrench for the project. Amazing the accuracy and repeatability of a good torque wrench.

Should have done this 50 yrs ago.

CDI is the industrial version of the snap on wrench. Great quality at a much lower price…

 

[taor]

NGK 6747 BR8EIX vs NGK 2668 BKR8EIX (Short reach plugs)

After hearing and reading about multiple incidents where a Lycoming engine blew a plug and adapter off, I came to the conclusion that I wanted to be able to torque the adapter at a different value than the plug. (First torquing the plug then adapter) The Kit Planes article on this process was helpful.

I first saw the part number NGK BKR8EIX in a thread and initially thought it was a typo. It's a valid part number and has one added benefit in that it has a 16 mm Hex Size vs the non-K part number 21 mm. Gap, reach, solid terminal, thread diameter (14 mm), thread pitch, heat range, resister value, torque specs, center electrode size, materials identical. There are 2 differences 1) The center electrode is non-projected on one and projected on the other. (See pic) and 2) The ceramic body on the K version is 10.0 mm and the non-K 11.5 mm. The rubber/elastomer boot still fits tight on the 10.0 mm body but obviously not quite as tight.

Seems like a good alternative to more easily torque the adapter while clearing the hex on the spark plug. FYI the Denso plugs on my long reach angle valve 390 have the smaller hex and projected center electrode like the K version of the short reach.

PIREP on the K version? Issues?

Hi:
I wonder if anybody knows where can I buy DENSO W27ESR-U spark plugs or the direct replacement on other brands like NGK, Champion, etc.?
I own a RV6A with a Lycoming O360 A1A
I'd appreciate your help-
Angel Olea
taor

 

[dmattmul]

Hi:
I wonder if anybody knows where can I buy DENSO W27ESR-U spark plugs or the direct replacement on other brands like NGK, Champion, etc.?
I own a RV6A with a Lycoming O360 A1A
I'd appreciate your help-
Angel Olea

Looks like a NGK BR9EIXSOLID is a more common cross reference.

 

[taor]

Looks like a NGK BR9EIXSOLID is a more common cross reference.

Thank you! I'll try it

 

[bjdecker]

I've been using NGK BKR9EIX -- stock # 2669, solid tip. No issues. The "BK" is a 5/8" hex instead of the 3/4" hex.

 

[Dad's RV-10]

I first saw the part number NGK BKR8EIX in a thread and initially thought it was a typo. It's a valid part number and has one added benefit in that it has a 16 mm Hex Size vs the non-K part number 21 mm.

NGK BKR9EIX -- stock # 2669, solid tip. No issues. The "BK" is a 5/8" hex instead of the 3/4" hex.

You're both right

 

[gear1]

One more data point: Thunderbolt IO 360 M1A 10:1 engine with P-mags. For the past 3200 hours the NGK BPR8EIX Projected nose plugs have been installed in my engines (yes plural). .032-.035 gap. Torqued with adapter and copper anti-seize to 17 ft-lb per Lycoming/Pmag instructions. Spark plugs are run for 200 hours before replacement. So far no problems.

Unfortunately these plugs have threaded terminals, so I use red LockTite to hold the terminals in place. Can anyone advise how to specify the solid terminal in my next plug order?

Great thread! A lot of good information. Thanks to everyone who has contributed!

 

[MiserBird]

NGK part # 6747 for solid terminal

 

[dmattmul]

One more data point: Thunderbolt IO 360 M1A 10:1 engine with P-mags. For the past 3200 hours the NGK BPR8EIX Projected nose plugs have been installed in my engines (yes plural). .032-.035 gap. Torqued with adapter and copper anti-seize to 17 ft-lb per Lycoming/Pmag instructions. Spark plugs are run for 200 hours before replacement. So far no problems.

Unfortunately these plugs have threaded terminals, so I use red LockTite to hold the terminals in place. Can anyone advise how to specify the solid terminal in my next plug order?

Great thread! A lot of good information. Thanks to everyone who has contributed!

Here's a comparison. Yours vs one with a solid terminal. NGK does not recommend anti-seize with their plugs, but the brass adapter might need. My guess is as long as used sparingly ok. I still like torquing the plug to 19 lb. ft (which is close to the middle of the NGK recommended spec for an aluminum head) and the brass adapter to 25 lb. ft.

 

[taor]

Hi:
I wonder if any of you has the replacement of DENSO 27 ESR-U in the Light Speed Engineering system? The only number I v´ e got was IK 27

 

[RV8JD]

Hi:
I wonder if any of you has the replacement of DENSO 27 ESR-U in the Light Speed Engineering system? The only number I v´ e got was IK 27

Here are the plugs Light Speed Engineering recommends for their systems. Be careful of short reach versus long reach plugs/adapters, and which ones are appropriate for your engine. See Post #16 if you're not sure.

Light Speed Engineering- Products- Sparkplugs

​

I've been happy with the Denso IK27 Iridium plugs for my LSE Plasma III EI on the 180 HP Lycoming YIO-360-M1B.

 

[riobison]

One more data point: Thunderbolt IO 360 M1A 10:1 engine with P-mags. For the past 3200 hours the NGK BPR8EIX Projected nose plugs have been installed in my engines (yes plural). .032-.035 gap. Torqued with adapter and copper anti-seize to 17 ft-lb per Lycoming/Pmag instructions.

Spark plugs are run for 200 hours before replacement. So far no problems.

One more data point: Thunderbolt IO 360 M1A 10:1 engine with P-mags. For the past 3200 hours the NGK BPR8EIX Projected nose plugs have been installed in my engines (yes plural). .032-.035 gap. Torqued with adapter and copper anti-seize to 17 ft-lb per Lycoming/Pmag instructions. Spark plugs are run for 200 hours before replacement. So far no problems.

As I'm just finally running an Electronic Ignition in my RV9 on an O320. I'm wondering why 200 hrs? Thats equivalent to an automotive average of 10,000 miles. Now I know before we had electronic ignition in our vehicles that is all we could get out of plugs. But today they appear to easily run 100,000 miles+- So, why not go 1/2 of that or 1000 hrs or even 500 hrs if we are nervous.

Our AC fine wires typically go 1500 hrs so why wouldn't the Auto Fine Wire plugs run at least as long?

 

[Toobuilder]

Our AC fine wires typically go 1500 hrs so why wouldn't the Auto Fine Wire plugs run at least as long?

One reason: because it’s easier to replace than clean. And at less than two bucks per plug, why not?

 

[Jetmart]

One reason: because it’s easier to replace than clean. And at less than two bucks per plug, why not?

I am using Denso 5347 plugs on my 390. Is there a cheaper alternative? They go for about $12 per plug.

​

 

[riobison]

One reason: because it’s easier to replace than clean. And at less than two bucks per plug, why not?

I can't even buy a spark plug for my lawn mower for $2 so Im not sure what your putting in. Generally a decent fine wire automotive plug for the Lycoming are $25+ each. And generally with the fine wire plugs there is very little cleaning. Maybe a ball of lead to pick out that takes less time to clean than it does to open up a new box. Always a risk getting a brand new plug that fails. It doesn't happen often but it does happen.

Tim

 

[Toobuilder]

I can't even buy a spark plug for my lawn mower for $2…

NGKBR8ES plugs are by far the most popular automotive plug we use in our aircraft engines. A 10 second search on Google turned them up for $1.99 at Summit.

NGK Spark Plugs BR8ES NGK Standard Series Spark Plugs | Summit Racing

Free Shipping - NGK Standard Series Spark Plugs with qualifying orders of $109. Shop Spark Plugs at Summit Racing.

www.summitracing.com

 

[rv8ch]

Here's the iridium with solid terminals for $6 at RockAuto:

More Information for NGK 6747

 

[airguy]

As I'm just finally running an Electronic Ignition in my RV9 on an O320. I'm wondering why 200 hrs? Thats equivalent to an automotive average of 10,000 miles. Now I know before we had electronic ignition in our vehicles that is all we could get out of plugs. But today they appear to easily run 100,000 miles+- So, why not go 1/2 of that or 1000 hrs or even 500 hrs if we are nervous.

Our AC fine wires typically go 1500 hrs so why wouldn't the Auto Fine Wire plugs run at least as long?

I run the NGK BR8ES plugs top and bottom, and running about 300 hours between annuals for the last few years. I can visually see (with no magnification) just the barest amount of erosion on the electrodes at annual - but at $2 each they get replaced, not cleaned.

 

[riobison]

I run the NGK BR8ES plugs top and bottom, and running about 300 hours between annuals for the last few years. I can visually see (with no magnification) just the barest amount of erosion on the electrodes at annual - but at $2 each they get replaced, not cleaned.

The BR8ES are a massive electrode. In Canada $4.50 to $5.00 Cdn pesos each and yes, that is cheap. The NGK 6747 are a fine wire at $14 to $15 cdn pesos each and still relatively cheap. Light Speed recommends fine wire and these don't appear to be one of them.
I'm running BKR8E1X that I paid around $20 each for the top 4. And will run on condition and aim for 500 hrs. Never really ever much cleaning to do on fine wires so not a big deal. Again a lot of vehicles today run 100,000 plus miles on the original plugs with zero problems. Yes autos are unleaded and we are fully leaded.

Here we can't buy much for $2.00

Tim

 

[airguy]

The BR8ES are a massive electrode. In Canada $4.50 to $5.00 Cdn pesos each and yes, that is cheap. The NGK 6747 are a fine wire at $14 to $15 cdn pesos each and still relatively cheap. Light Speed recommends fine wire and these don't appear to be one of them.


Tim

Correct, I bought my engine with 105 TTSNEW back in 2010 and it can with the Plasma 1 setup on it. I talked to Klaus about one day before installing it in my plane, and he said the BR8ES which were in the engine when I received it were acceptable, so that's what I ran. I guess later on he changed his mind and started recommending fine-wire plugs, but I've never had a lick of trouble from the massive electrodes.

 

[riobison]

, but I've never had a lick of trouble from the massive electrodes.

You never had any problems on the bottom plugs with fouling or lead?

 

[airguy]

You never had any problems on the bottom plugs with fouling or lead?

Not once yet. I lean aggressively on the ground, and fly LOP in cruise/descent. The only time I go rich is for takeoff/climb and entering the pattern for landing. 1560 hours and 8 years so far on auto plugs. To be fair, only about 1/3 of that time has been on 100LL - when I'm on long trips and need to buy fuel away from home. The rest of the time I am burning 93E10 from my private strip at home.

 

[Toobuilder]

Not once yet.

Same here. Ive been running this plug top and bottom for 20 years now on plenty of airplanes. They ALWAYS hit the 4500 ohms out of the box and are perfectly gapped. Never had an issue with them. And when they go in the trash, they still look like new.

 

[riobison]

Same here. Ive been running this plug top and bottom for 20 years now on plenty of airplanes. They ALWAYS hit the 4500 ohms out of the box and are perfectly gapped. Never had an issue with them. And when they go in the trash, they still look like new.

Shouldn't really be surprised with zero problems. 80+ yr old sparkplug technology in aviation with Astronomical prices and no real change in technology. Like our engine's and propellers.