Fine Wire Spark Plugs

[201er]

My Mooney came to me with fine wire but other guys and mechanics have beens suggesting not to go with them in the future. I don't know about this kind of stuff at all so I was hoping you guys could let me know the differences, merits, and values of fine wire vs not spark plugs and how that works out in your Mooney.

[jetdriven]

You can do a search but the fine wires are better in every measurable category but cost.  But, hey, yours are free.

here are some benefits:

• 
  
• last 2000 hours (vs 400-1000 hours for massives)
  
• rarely require regapping if at all
  
• harder to foul with lead
  
• fires better in a cylinder that uses oil.
  
• able to provide a more open spark, which in theory allows you to run leaner before roughness. Ross and others have countered that fresh massives are similar, so YMMV.
  
• RAM aircraft claims a .02% improvement in BSFC (2% more efficient)
  

http://www.ramaircraft.com/Maintenance-Tips/Spark%20Plugs-Fine-Wire-vs-Massive.htm

http://www.avweb.com/news/maint/spark_plugs_198595-1.html

 

If you run LOP these benefits are more important.  We installed a fresh set some 75 hours ago and it made a night and day difference from worn out massive plugs.

 

[N1026F]

are these the Iridium plugs?

[jetdriven]

Autolite (now Tempest) fine wires.  Yes the literature says Iridium.  Iridium and platinum do not erode as fast as steel does, so the spark plug gap remains constant for longer. 

 

http://www.aero-news.net/index.cfm?do=main.textpost&id=c7d0dd71-691c-4bcf-a6fc-21218807dfba

[201er]

Besides price what's the disadvantage? I had guys telling me that the fine wire could be the same or worse in some cases. Also is it really better to have fine wire rather than to replace normal ones more frequently?

[jetdriven]

AFAIK they are just plain better in all categories than cost. They are 1950s technology rather than 1910s.   But amortized over 2000 hours they are cheaper.  That and A&P shops cannot charge you to clean plugs in a blast machine because you dont do that.  It ruins them.    Id love to see an article saying massives are better.

[donshapansky]

Interesting fact is I was having trouble getting my Rocket to run smoothly LOP, talking to Tim Roehl at GAMI he said the fine wires don't work well LOP. My fine wires looked great and had about 500 hrs on them. After some deliberation I changed to the old massive electrodes and voila! I get 15.5 gph LOP hottest cylinder 360 -370 depending OAT in Texas. Interesting is my numbers vs the Missile in cruise at 8,500' I get 190 - 194 KTAS depending on OAT @ 15.5 gph. The difference is I have adjusted my fuel flow to match my boost for max power, eg 37 gph and 37 " MAP with CHT's in the 330 - 350 F @ 1700' ft/min 125 KIAS or cruise climb of 155 KIAS @ 900'/min.

Don

[orangemtl]

Quote: donshapansky

Interesting fact is I was having trouble getting my Rocket to run smoothly LOP, talking to Tim Roehl at GAMI he said the fine wires don't work well LOP. My fine wires looked great and had about 500 hrs on them. After some deliberation I changed to the old massive electrodes and voila! I get 15.5 gph LOP hottest cylinder 360 -370 depending OAT in Texas. Interesting is my numbers vs the Missile in cruise at 8,500' I get 190 - 194 KTAS depending on OAT @ 15.5 gph. The difference is I have adjusted my fuel flow to match my boost for max power, eg 37 gph and 37 " MAP with CHT's in the 330 - 350 F @ 1700' ft/min 125 KIAS or cruise climb of 155 KIAS @ 900'/min.

Don

[donshapansky]

I experienced very unpleasant intermittent roughness saying to me it was unhappy. I'm within .4 gph and when the richest cylinder (No.2) is -50 LOP the leanest (No.5) is -85 LOP.

The DA makes a difference of course as to where LOP occurs, in Texas summer it's always 15.5 to 16.0 gph vs winter at 16.5 gph. My power settings were suggested by GAMI and Powermaster agreed, Bill flies a 210 with the same engine package as me (ECI Nikisil) and predicted my summer fuel flow to the tenth of a gallon.

My power settings are 32.5" MAP @ 2450 rpm for 70 - 73% depending on fuel flow according to the EDM 930. I can finally close the cowl flaps mostly by over half in cruise and the hottest cyclinder will be No. 2 vs No. 5 ROP. The oil stays golden colored through 30 hrs with no oil added. I have an M20 air/oil separator and start off at 12 qts and end up over 11 qts at change time of 30 hrs which is usually monthly.

However I have acquired an Aerostar 700, which has yet to enter service so it may not get as much use next year.

 

Don

[donshapansky]

I forgot to answer your one question about the GAMI findings, Tim said they found that the fine wire plugs did not operate well LOP, his words were "sorry I know you spent money with expectations but we have found they don't offer any solutions for LOP ops"

[knute]

I'm intrigued by GAMI's apparent stance on fine wire plugs for LOP, since Champion fine wire plugs are standard equipment on most Cirrus SR22s, which use the TAT turbo system for which GAMI did the R&D. 

Do a search on Mooneyspace for fine wire plugs, and you'll find another thread or two that suggests that they do just fine LOP, and my own experience (>60 hours so far on Tempest fine wire plugs) is very positive-  I can run smooth at 80% power (low altitude to get that) well past 100 deg LOP before it stumbles, and I could never get close to that with the previous massive plugs even when freshly cleaned & gapped.

(Distracting side note- GAMI has issued a service bulletin related to ceramic cracking on Champion fine wire plugs in the Cirrus application, but there is no evidence of this on the Tempest fine wire plugs, nor has evidence been presented that this is an issue with fine wire plugs in general; manufacturing defect?)

-Knute

'66 M20E - N6066Q - KSQL (San Carlos, CA)

[FlyDave]

Quote: knute

(Distracting side note- GAMI has issued a service bulletin related to ceramic cracking on Champion fine wire plugs in the Cirrus application, but there is no evidence of this on the Tempest fine wire plugs, nor has evidence been presented that this is an issue with fine wire plugs in general; manufacturing defect?)

-Knute

'66 M20E - N6066Q - KSQL (San Carlos, CA)

[AndyFromCB]

Quote: orangemtl

That is very interesting Don.  I cannot imagine why fine wires would contribute to difficulty in running smoothly LOP with balanced injectors for balanced peaking.  While I cannot imagine what mechanism would cause the problem, it is impossible to argue with the huge experience of the Gami folks on such a point.  Did the say universally it is a problem or just a source of problem?  Why am I curious?  I have a rocket, and a set of fine wires on lowers and massives on uppers.  No Gami's but my gami test shows 5 cylinders peaking within 0.2gph but the 6th is 0.7gph late to peak.  Almost great.  I can run LOP smoothly at 55% and below but not more power than that. I was blaming the injectors and about to get new gamis but could it really be my lowers set of fine wires?!

[DaV8or]

Quote: astelmaszek

Strange - happened again - my identity was switched and this is really my comment to Don - from Me Erik.  Aviatoreb

[orangemtl]

Quote: orangemtl

That is very interesting Don.  I cannot imagine why fine wires would contribute to difficulty in running smoothly LOP with balanced injectors for balanced peaking.  While I cannot imagine what mechanism would cause the problem, it is impossible to argue with the huge experience of the Gami folks on such a point.  Did the say universally it is a problem or just a source of problem?  Why am I curious?  I have a rocket, and a set of fine wires on lowers and massives on uppers.  No Gami's but my gami test shows 5 cylinders peaking within 0.2gph but the 6th is 0.7gph late to peak.  Almost great.  I can run LOP smoothly at 55% and below but not more power than that. I was blaming the injectors and about to get new gamis but could it really be my lowers set of fine wires?!

[MooneyMitch]

Has anyone acutally experienced a cracked/broken insulator on a Champion fine wire?  Just removed our 8 for inspection and found one with a broken insulator.  367 hours on plugs since new.  They are UHRM38S.

[knute]

Quote: Mitch

Has anyone acutally experienced a cracked/broken insulator on a Champion fine wire?  Just removed our 8 for inspection and found one with a broken insulator.  367 hours on plugs since new.  They are UHRM38S.

[MooneyMitch]

Whoops, you're correct.   They are the Unisons.  My mistake. 

[jetdriven]

~120 hours on ours and doing great.

[donshapansky]

I have recently aquired a SuperStar with 350 Lycs that from the Chieftan Navajo and other large twins. The max allowable mag drop is 175 rpm, this was written as a snag at the recent annual. On the run up after I got the airplane home this drop was still there. I pulled a plug to see what was installed. It had fine wire Champion plugs that were 3 or more yrs old but less than 100 hrs TT, I installed a set of Tempest massive electrode plugs.

I wasn't even thinking about the mag drop I just had heard on the Aerostar forum of high altitude missfires and the Tempest plug construction that seems to be an improvement over the older methods and materials, so I was being proactive.

The first run-up I realized the mag drop was eliminated!