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Fine wire or massive?

Abbygirl1

Well Known Member
OK guys....opinions needed. Annual conditional coming up and I need to replace the plugs (Lyc O-320 D1A). Normally use 90 octane no-ethanol gas. Never any probs. Tried 100LL on a trip and fouled a plug. Should I bite the bullet and put in fine wires, or new massives?
 
I like the ___37BY spark plugs. They are the massive electrode plugs that have the tip and electrodes sticking out to reduce lead fooling.

Others swear by the fine wire. The fine wire are a LOT more money. I have had no issue with the massive electrode plugs so I stick with the less expensive option.
 
I was constantly having to clean my plugs even though I aggressively leaned on the ground running 100LL. I bit the bullet and put in the fine wires and it is worth it to me. That and running TCP fuel additive and I haven't cleaned a plug since.....If you can run auto gas all the time then maybe the massives will work but they claim the fine wires will last to TBO. Coarse Ive only got 20 hrs on my plane so take that for what its worth!:eek:
 
I was constantly having to clean my plugs even though I aggressively leaned on the ground running 100LL. I bit the bullet and put in the fine wires and it is worth it to me. That and running TCP fuel additive and I haven't cleaned a plug since.....If you can run auto gas all the time then maybe the massives will work but they claim the fine wires will last to TBO. Coarse Ive only got 20 hrs on my plane so take that for what its worth!:eek:


Mike, I had the same problem a few years ago with a Mooney. Changed to Tempest fine wires....problem solved. But that is a much more expensive choice now. $24.50 ea vs $74 ea.
 
half n' half ?

some of us run fine wire on the lower, massive on top.
no convincing data proving anything that I know of....but YOU'll see the story next time you pull them!

.....can't hurt eh?
 
some of us run fine wire on the lower, massive on top.
no convincing data proving anything that I know of....but YOU'll see the story next time you pull them!

.....can't hurt eh?

Except now you won't want to rotate plugs from top to bottom for more even wear?

Fine wire costs 3x but are also supposed to last 3x longer.
 
OK guys....opinions needed. Annual conditional coming up and I need to replace the plugs (Lyc O-320 D1A). Normally use 90 octane no-ethanol gas. Never any probs. Tried 100LL on a trip and fouled a plug. Should I bite the bullet and put in fine wires, or new massives?

If you think you will be putting in EI in the future you might as well go with the massive plugs (cheaper) because most likely you will want to switch to auto plugs with EI.

Another consideration is that if you drop a plug it is much less painful with the cheaper plugs.

Jim
RV9A flying
 
Except now you won't want to rotate plugs from top to bottom for more even wear?

Fine wire costs 3x but are also supposed to last 3x longer.

That seems like more reason to put the fine wires on the bottom. I can replace the top plugs 3 time before the bottoms need replacing ...and eliminate (virtually) all the fouling of the bottom plugs.
 
Tempest UREM37BY

I was dealing with the same lead fouling problem in my RV6 running O-360-A4A. The builder/seller always run car gas so this fouling issue is new to the plane. The plane came with Champion plugs - 7 massive and 1 fine wire.

I first looked into fine wire plugs, and discovered a lot of Bonanza drivers were having their share of problems with fine wire. I am not sure if that is unique to Continental or maybe only for Champion fine wire plugs. In any case, I ruled out fine wire because the cost is just too high. I know you can run them longer, but I don't see the manufacturer guaranty the plugs for the life of engine TBO so if anything goes wrong it is on me.

My research then found Lycoming Service Letter L192B recommending 37BY plugs:
http://www.lycoming.com/Portals/0/t...s/SL 192B (01-19-1988)/Spark Plug Fouling.pdf

So I order 8 Tempest UREM37BY plugs from Chief for just under $200. I only had 3 flights so far with no indication of fouling plugs.

Just one data point. I hope it helps.
 
The resistors will usually fail in a plug way before the electrode wears out. This is especially true of Champion plugs, or at least the old Champions before they supposedly changed the internal resistors. The Resistors in a fine wire plug will not last any longer than in a massive type plug. The fine wire plugs do not foul due to bridging as often as a massive plug due to the extra clearance between the center electrode insulator and the inside diameter of the housing, but they will still foul just the same due to over priming or poor technique and flooding on start up. The 37BYs do a good job of keeping the lead build up away from the electrodes.
 
I have over 1,000 hours on the Tempest Wine Wire plugs in both top and bottom of my RV-10 and love them. I just pick out a few lead balls at annual time, but other then that they are clean with running 100LL.


Ray Doerr
RV-10 (N519RV)
 
....

The Resistors in a fine wire plug will not last any longer than in a massive type plug. The fine wire plugs do not foul due to bridging as often as a massive plug due to the extra clearance between the center electrode insulator and the inside diameter of the housing, but they will still foul just the same due to over priming or poor technique and flooding on start up.

....


Good point. I am wondering if spark is stronger between massive electrodes vs fine wire.
 
I have a low compression O320E3D that is supposed to be very prone to fouling. Have the Champion massive plugs. After 100 hours I have had zero lead fouling issues using the Lycoming recommended techniques:

Lean aggressively on the ground
Lean after reducing takeoff power and throughout cruise
Run engine at 1800 rpm for 15-20 seconds just prior to shut down

I just inspected my plugs and all looked excellent. Not saying it will work for everyone, but sure works for me so far.

Chris
 
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I like the ___37BY spark plugs. They are the massive electrode plugs that have the tip and electrodes sticking out to reduce lead fooling.

Others swear by the fine wire. The fine wire are a LOT more money. I have had no issue with the massive electrode plugs so I stick with the less expensive option.

Same experience here. 300 hours and never had fouling issues or found deposits on the plugs. I always run LOP in the air and never lean on the ground.

Larry
 
Good point. I am wondering if spark is stronger between massive electrodes vs fine wire.

A hotly debated topic. In my experience, a hotter spark will provide no improvement to performance under normal circumstances. It will, however, help to avoid misses and better maintain combustion timing in overly lean or overly rich mixtures.

Spark energy is dictated by the power of the coil setup, which is throttled by the sparkplug gap. electrode material will have no meaningfull effect on spark energy, though it does impact electode wear and longevity.

Larry
 
I have a low compression O320E3D that is supposed to be very prone to fouling. Have the Champion massive plugs. After 100 hours I have had zero lead fouling issues using the Lycoming recommended techniques:

Lean aggressively on the ground
Lean after reducing takeoff power and throughout cruise
Run engine at 1800 rpm for 45 seconds just prior to shut down

I just inspected my plugs and all looked excellent. Not saying it will work for everyone, but sure works for me so far.

Chris

Are you doing this in front of your hangar? don't think that would go too well where I'm at.....:rolleyes:
 
Are you doing this in front of your hangar? don't think that would go too well where I'm at.....:rolleyes:

Yep, I do this in front of my hangar, so long as there aren't others nearby (there usually aren't). There is nothing else nearby where I am located, so no issues there. Obviously you may have a vastly different situation with homes, etc, nearby. If I am at a different field, I'll use my best judgement to decide if it is reasonable or not to do it. I certainly don't do it on a busy ramp in front of an FBO.

Chris
 
I have 1200 hrs on my Husky with fine wires and zero issues. Runs smoother and last a lot longer. IN the RV i use NGK's and just replace them yearly
 
You mean "always" lean on the ground right???

No.

There is no need to lean, via the red knob, below about 900-1000 RPM, as the mixture is controlled directly by the idle mixture adjustment and I have that adjusted for an optimum mixture; No need for further adjustment. That leaves taxi above 1000 RPM. Leaning, via the red knob, is done by setting the maximum fuel flow through the carb or injector with no minimum setting and no other interaction with units variable mixture function. A Mixture leaner than that provided by the carb or inj's internal metering circuit(s) can only be set for a specific MAP / RPM configuration by limiting the fuel flow to a specific rate (that is what your red knob does). The optimum fuel rate required by your engine is constantly changing based mostly upon the RPM & MAP. The setup we have only realistically works for constant power settings and provides no help for variable power settings, such as taxiing.

If you don't believe me run a test. Run your engine up to 1400 and set the mixture for peak EGT or on the lean side of peak. This would be considered "leaned." Then push in the throttle and try to get to 1600 RPM. Conversely, drop it to 1200 and you'll find that it is no longer at Peak or LOP.

My engine (100 hours as O-320 / 200 hours as IO-320) does not run filthy rich at lower RPMs like it does at higher RPMs. In 300 hours, I have never had a fouled plug and never had an unsuccessful run-up after taxiing. My speculation is that many engines do no have the idle mixture set properly and this causes the fouling problems and this is fixable without using the red knob. Yes, I am running richer than necessary while taxiing above 1000, but there is not much I can do about it and any build up will burn right off when I push the throttle to full on take off or when I run it up before shut down.

As I mentioned, I lean religiously once my wheels leave the ground and my power settings are less variable.

EDIT: I will add that the RPM drop method of setting idle mixture is a bit crude & difficult to perform, as the mixture control is very course at lower fuel flow rates. It can give erroneous results to those not familiar with carb tuning. I set my idle mixture via best vacuum or lowest MAP. This is a much easier method that provide better feedback to the operator. Unfortunately it means standing next to a spinning prop.

Larry
 
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Very Interesting

Love to hear more about your leaning procedures and as my tag line suggests,
I don't even believe everything I know anymore but you are defying 100 years of leaning procedures by simply suggesting that everyone has poorly adjusted carburetors.
Maybe in a new thread, we are getting too far away from spark plug issues.
 
No.

There is no need to lean, via the red knob, below about 900-1000 RPM, as the mixture is controlled directly by the idle mixture adjustment and I have that adjusted for an optimum mixture; SNIP

Larry

Larry,

A lot of people, including me, strongly disagree with leaving the engine rich on ground. I lean until the engine almost stops.

I note that from my reading the leading cause of Lycoming engine stuck exhaust valves is from running the engine excessively rich.

Carl
 
No.

There is no need to lean, via the red knob, below about 900-1000 RPM, as the mixture is controlled directly by the idle mixture adjustment and I have that adjusted for an optimum mixture; No need for further adjustment.

...

Larry

I certainly don't have your level experience with these engines, but it seems like if lead is an issue, "optimum mixture" may be too rich. It may be optimum for combustion, but still result in more lead fouling than needed. Since there is no harm in leaning a good bit beyond "optimum" at these low power settings, wouldn't that help prevent lead build-up?

In practice, some people just seem to have issues, and others don't. With my low-compression setup, I am fairly religious about leaning on the ground as well as in flight when able, and after almost 200 hours have never had a fouled plug or any other lead issues. Maybe what I am doing is working, maybe it wouldn't be an issue anyways, but it doesn't seem to hurt. I am open to more knowledge though!

Chris
 
I certainly don't have your level experience with these engines, but it seems like if lead is an issue, "optimum mixture" may be too rich. It may be optimum for combustion, but still result in more lead fouling than needed. Since there is no harm in leaning a good bit beyond "optimum" at these low power settings, wouldn't that help prevent lead build-up?

In practice, some people just seem to have issues, and others don't. With my low-compression setup, I am fairly religious about leaning on the ground as well as in flight when able, and after almost 200 hours have never had a fouled plug or any other lead issues. Maybe what I am doing is working, maybe it wouldn't be an issue anyways, but it doesn't seem to hurt. I am open to more knowledge though!

Chris

First, the most common problem that people are looking to address with leaning on the ground is lead fouling. Unfortunately lead fouling has little to do with mixture, it really has to do with heat. Your fuel has scavanger additives that will help prevent lead from depositing by converting it's form (lead oxide -> lead bromide). Unfortunately, this conversion requires a certain temperature and you typically won't get to that combustion temp until around 1200 RPM. The best way to eliminate lead deposits is to never run your engine below that specific combustion temp (not that it is a realistic goal). Maintaining an optimum mixture will marginally reduce the potential for deposits, but don't kid yourself, the deposits form at pretty much the same level at most mixture levels. The deposits are not due to a rich mixture level. All of the fuel (rich, lean or otherwise) contains lead oxide and all of that lead oxide is available to deposit in the chamber unless it is converted to lead bromide (the lead oxide is not burned or otherwise changed during the combustion process like the hydrocarbons are - this is why they add scavengers). The mixture does nothing to accelerate or inhibit the potential for that lead to deposit. Only conversion to lead bromide can prevent the deposits. It does this by getting the combustion temp up high enough for hte scavangers to do their work

Sure, if you reduce the total fuel introduced to the combustion chamber by 5% by leaning from fitlhy rich to optimum, you can theoretically reduce deposits by 5%, but I can't imagine that helps.

Now, leaning can increase combustion temp, however, it is not moving it much at low RPMs. I have not done the research, but I doubt you could be precise enough in your leaning activities to make that much of a difference. Also, overly lean is just as cold as overly rich. The only thing that could help is to maximize combustion pressure (think red box), thereby increasing combustion temp. That said, anything that you can do to reduce the total fuel delivered and, more importantly, to get to the desired combustion temp isn't going to hurt. I am just not convinced it is helping much.

My goal here is not to encourage anybody to change their behavior, only to encourage people to stop honoring old wives tales and do the research necessary to truly understand what is happening in your engine and develop strategies to address any issues.

Lead deposits are a reality with 100LL. There are steps that can be taken to eliminate the build up. There is a reason that Lycoming recommends running your engine up to 1200+ RPM for 30 seconds before shut down. This helps to burn off the depoists that were built up during the low RPMs during taxi. It does this by getting the combustion temp up high enough for hte scavangers to do their work and convert the lead oxide. Spark plug type makes a big difference. The plug mentioned earlier in this thread was designed specifically to reduce deposits by making the crevices bigger and letting the deposits form in such a way that they won't bridge to the center electrode.

I would argue that some of these steps and other issues create the difference between user experiences with fouling and not the mixture setting. Again, just some food for thought and not a crtiicism on how other manage their engine.

Larry
 
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Larry,

A lot of people, including me, strongly disagree with leaving the engine rich on ground. I lean until the engine almost stops.

I note that from my reading the leading cause of Lycoming engine stuck exhaust valves is from running the engine excessively rich.

Carl

My belief is that the exhaust valve problem is due to lycoming's inadequate oil flow to the valve box. The lack of cooling available to the exhaust valve allows it to run hot enough for the oil to coke (oxidized oil due to heat) and create the deposits. I imagine that overly rich mixtures could exacerbate that build up, but it is far more likely that would come from running rich at high power, when the valves are much hotter and not during ground ops when they are colder. Deposits need heat to form. Look at the bottom of your piston. The build up is MUCH heavier on the ceiling than the sides, because it is much hotter. If it was just mixture and not heat, your intake valve would have the build up as well.

I will add the following: Compare the build up on the exh valve stem. Every picture I have seen show it as a very hard and brittle, deep black substance. That is coked oil or other carbon based element. Compare that to the lead build up up that you chip out of your spark plug. It is a gray cast and not brittle. Lead, by it's elemental makeup, cannot be brittle. It is just like the build up we see on our piston sides around the ring lands. We know this to be coked oil, as fuel doesn't get below the top ring, rich lean or otherwise (at least under normal circumstances and excluding the very slight trace of fuel from blowby).

I also want to reiterate that I am not necessarily rich on the ground. My idle mixture is adjusted well and I am NOT rich when running under 1000 RPM (this is adjusted via the Idle mixture and requires no additional leaning). It is only when I raise the RPM above that level am I not leaning. That, however, should not assume that I am rich. We know the carbs and Inj's run very rich at high air flows. I have not done enough testing or research to assume they are also filthy rich in the lower RPM levels (1000-1400 RPM). I speculate that they are not that bad down there.

Just a competing opinion for consideration. I'll restate that I am not trying to change opinions on leaning. A poster asked why I don't lean on the ground and I am providing the logic and rationale that I use for my approach.

Larry
 
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Here is an interesting article about lead fouling, written by a fuel company. You will not find anything about leaning or rich mixtures, but will see a lot of good information and advice on dealing with lead fouling.

http://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/technical-talk/techart-18-30071600.html

This is the type of information that I tend to absorb. I routinely dismiss the things I hear arond the aiport regarding engines as most of it I have proved inaccurate. There are still people telling me my engine will blow up because I cruise lean of peak. Same guys tell me to pump the throttle on my carb twice before I hit the starter button. You get the drift.

Larry
 
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