Lycoming IO 360 Sparkplugs (BY type)

[redbaron1982]

Hey, this is kind of a idiot question. 

So I keep having fouling issues with my bottom spark plugs so I was planning to get the BY model from tempest. 

The thing is that my airplane has 3/4 #20 leads. So no BY model for me. 

I don't know from where I got the (now I think wrong idea) that the equivalent to BY for my leads would be the URHB37E. 

So I got 4 to replace my bottom spark plugs and first they don't have the protruding electrode like the BY ones and also the thread into the cylinder is much longer. 

Looking at Lycoming SI 1042, long reach plugs are to be used in special cylinders. So is not that you can go from normal to long reach on the same engine. 

Am I correct? Is there any alternative (different from fine wires) to have a spark plug that helps me with the fouling issue I keep having?

The reason why I don't want to use fine wire is because of the crazy price. 

[PT20J]

I don't believe that there is a BY plug for 3/4-20 leads. The approved BY plug for an IO-360 is an (U)REM37BY. (U if it is Tempest). According to SI 1042, you should only use long reach plugs (URHB37E) if the cylinders are marked with yellow paint between the spark plug hole and the rocker covers. You could change the ignition harness to 5/8-24 and then you could use all UREM37BY plugs which makes rotating simpler.

[redbaron1982]

11 hours ago, PT20J said:

I don't believe that there is a BY plug for 3/4-20 leads. The approved BY plug for an IO-360 is an (U)REM37BY. (U if it is Tempest). According to SI 1042, you should only use long reach plugs (URHB37E) if the cylinders are marked with yellow paint between the spark plug hole and the rocker covers. You could change the ignition harness to 5/8-24 and then you could use all UREM37BY plugs which makes rotating simpler.

That's some bad news, lol. So my options, to improve my current condition, is changing the whole harness for one that is 5/8-24 or get fine wires. Both options way above $500. So I guess I'm going to keep cleaning the bottom sparkplugs and get better at leaning to prevent fouling.

[dzeleski]

32 minutes ago, redbaron1982 said:

get better at leaning to prevent fouling.

When you taxi the mixture should be pulled back so far that the thing is barely running. Any throttle advance should have it want to die.

When you are in your decent and your checklist says "FULL RICH" dont do that either. Leave it leaned out, for the entire decent and approach. If you want to go full rich on short final fine but even then you can go 50% throttle, mix full, clean up the plane, trim, WOT, very quickly. I personally alternate LOP and ROP operations. If your engine runs LOP do it a few times a month to keep the engine a bit cleaner. If you are at a higher DA its even more important to not go crazy with the fuel.

That being said I have fine wires in my J and dont have fouling issues. I pull the plugs every 50 hours and inspect them but generally dont have much to do.

[Shadrach]

If your plugs are fouling, the mixture knob is not going to affect your situation much if at all. Ground leaning is a fine idea, especially at high DAs but a properly set up Lycoming IO360 should idle and taxi just fine at full rich with no fouling of the plugs.  Ground leaning has only been a thing for about 30 years. What kind of cylinders do you have?  Oil may be coming through valve guides. First step is a wobble test.

https://www.lycoming.com/sites/default/files/attachments/Procedure%20to%20Determine%20Exhaust%20Value%20and%20Guide%20Condition.pdf

[redbaron1982]

1 hour ago, Shadrach said:

If your plugs are fouling, the mixture knob is not going to affect your situation much if at all. Ground leaning is a fine idea, especially at high DAs but a properly set up Lycoming IO360 should idle and taxi just fine at full rich with no fouling of the plugs.  Ground leaning has only been a thing for about 30 years. What kind of cylinders do you have?  Oil may be coming through valve guides. First step is a wobble test.

https://www.lycoming.com/sites/default/files/attachments/Procedure%20to%20Determine%20Exhaust%20Value%20and%20Guide%20Condition.pdf

One clarification, maybe fouling is not the best term. They get massive lead deposits. I need to take them out again, last time I did was 20 hours ago, but my last flight I did an in-flight mag check and the left magneto, although was running "smoothly" it was misfiring every 3 or 4 seconds. I suspect that is a spark plug. And was planning on replacing them for the BY type already to see if I can avoid having to clean them every 20 or so hours.

[Shadrach]

26 minutes ago, redbaron1982 said:

One clarification, maybe fouling is not the best term. They get massive lead deposits. I need to take them out again, last time I did was 20 hours ago, but my last flight I did an in-flight mag check and the left magneto, although was running "smoothly" it was misfiring every 3 or 4 seconds. I suspect that is a spark plug. And was planning on replacing them for the BY type already to see if I can avoid having to clean them every 20 or so hours.

I’ll take for granted that you’ve already swapped the plugs around or replaced them and are still having the same problem. The reason I say is because an ignition system that is operating suboptimally will collect lead. So then it becomes a chicken or the egg proposition. I can tell you that I have owned and operated an IO360 with massive plugs for over 20 years. Lead it’s never been a problem. I have to clean them at annual of course but the few failed mag checks I’ve had were never caused by lead fouling.

[PT20J]

Lead fouling is caused by rich mixtures (more lead in the cylinder) and low operating temperatures (poor lead scavenging which takes heat to initiate the chemical reaction). 

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

Skip

[cliffy]

In 2,000 + hrs of flying my M20D I have never had to clean my plugs "every 20 hrs" and I've run massives the entire time. 

I got almost 800 hrs on the last set of massives. 

How are you running your engine?

What kind of procedures are you using for climb, cruise and decent? 

Are you leaning aggressively while on the ground?

[N201MKTurbo]

I run SH260s  I buy all the new old stock I can find on EBay that are reasonable. I have about 25 new in tubes. I think they work better than fine wires. Three electrodes per plug. And approved for my engine. Don’t go buying up all my plugs now. They haven’t made them since the 70s.

[redbaron1982]

On the ground I'm idling always at 1000-1200rpm with the mixture aggressively leaned. 

I usually climb WOT / 2600RPM / Full Rich. I don't lean until I level off mainly because I'm still working on solving a high CHT issue. 

I do the rest of flight with the mixture leaned but still ROP, 50F rich of peak. 

[KSMooniac]

You should climb at 2700 RPM and lean in the climb using the Target EGT method. You also shouldn't run 50 ROP unless below 65% power, but that is the advanced course.

Perhaps your mags are weak, or harness? Or mixture not set correctly? Something is not up to par IMO.

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