why are my plug electrodes doing this? | FerrariChat
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why are my plug electrodes doing this?

Discussion in 'Technical Q&A' started by luckydynes, Aug 19, 2008.

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  1. luckydynes

    luckydynes F1 Rookie

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    #1 luckydynes, Aug 19, 2008
    I thought it was from the wide gap but I pulled the plugs today and have only been running .03 gap and it's starting on some of 'em.

    I'm running an MSD Dis4 with the Denso motorcycle coil on plugs . . plugs are BPR7ES.

    I opened the gap up to .04 and the butt dyno is telling me it's a good thing, only I think it's gonna accelerate this problem . .. shall I go to colder plugs or some kinda race plugs?

    thanks,

    Sean
     
  2. luckydynes

    luckydynes F1 Rookie

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    #2 luckydynes, Aug 19, 2008
    Last edited by a moderator: Sep 7, 2017
  3. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #3 Rifledriver, Aug 19, 2008
    A 7 isnt all that hot a plug but I suppose it depends what you are doing with it. The cheap and easy thing to do is screw a set of 8s in it and see what happens.
     
  4. luckydynes

    luckydynes F1 Rookie

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    #4 luckydynes, Aug 19, 2008
    high compression though . . 11.5:1 .. . I'll put colder plugs in
     
  5. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #5 Rifledriver, Aug 19, 2008
    That explains a lot.

    If you are going to open the gaps watch out for detonation.
     
  6. luckydynes

    luckydynes F1 Rookie

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    #6 luckydynes, Aug 19, 2008
    yep .. that's exactly what I had problems with at a wider gap and ended up blowing a head gasket . .. closed up the gap and can run 36 deg full for just the typical street driving .. then I had this condition where it seemed like if I was off the pipe for say 5 minutes the next time I nail it she coughs and sputters like loss of spark .. . so started thinking I was blowing out the spark and reading other threads with guys and MSD's they were told to run more gap . ..

    soooo .. today I open up the gap and the cough gets worse .. I talked with Htech months ago and we talked about the massive amount of EMF that's coming off the Dis4 running all 8 coils in waste spark to boot . . . the guy implied that hard spark/combustion conditions (a/f not correct, cylinder temp not high, etc) will increase the EMF 'cause the MSD is gonna push harder if that makes any sense (not an EE at this frickin' point) . .. thinking about this made me re-route the input wires completely away from the ouptput wires of the MSD (even though they're bundled together in one loom from the factory .. the Htech guy thought this was a bit problomatic since the MSD kicks like 500V on the primary??? .. that seems EE fundamental not good for a 12V square wave input but maybe it's not fast enough but again I'm not EE and this is how MSD had it) and that stopped that cough (concidence . . jiggled connection somewhere?) and kept the power pretty good at .04 gap but I have some avgas mixed in too . . anyway seemed like the cough was related to plug fouling but I thought if the MSD has all this juice how can that be and look at the plugs they don't look fouled .. so is it that plug buildup/fouling will increase EMF or should I just open another beer? ;)

    I had a point to begin with . . oh yeah . .there was a cough that was related to EMF caused by plug fouling . . sheeesh

    cheers and thanks for the input
     
  7. KKRace

    KKRace Formula 3

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    #7 KKRace, Aug 19, 2008
    Running the wires to the coil from the MSD near the wires that go from the dist to the MSD is a pretty common cause of problems. The signal from the dist is weak compared to the one coming from the MSD to the coil. If you run the two pairs of wires together you get crosstalk and a real bad mis under load. I had this happen to me and separating the two pairs fixed the problem right away. Don't even run them through the same hole in the firewall etc.
     
  8. luckydynes

    luckydynes F1 Rookie

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    #8 luckydynes, Aug 20, 2008
    yeah makes sense and is pretty fundamental I guess .. I've got everything crammed in a compartment on the left side and I swear the input wires were only parallel with the output wires a couple inches where they all meet at the connector . . . I have another DIS4 I wanted to mount in there but I think I better mount both of them somewhere else.

    cheers
     
  9. hotrod406

    hotrod406 Formula Junior

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    #9 hotrod406, Aug 20, 2008
    Forgive me for being dense, but what are we looking at in that pic? It's blurry but it looks fairly normal to me.
     
  10. luckydynes

    luckydynes F1 Rookie

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    #10 luckydynes, Aug 20, 2008
    the center electrode looks like it's leaning to one side
     
  11. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #11 Steve Magnusson, Aug 20, 2008
    Are you running leaded fuel?
     
  12. fastradio

    fastradio F1 Rookie
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    #12 fastradio, Aug 20, 2008
    What does this have to do with running high compression pistons, heat range or plug gap?
     
  13. luckydynes

    luckydynes F1 Rookie

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    #13 luckydynes, Aug 20, 2008
    Last edited: Aug 20, 2008
    some avgas mixed in . .. . ???

    edit: 100 "LL" which means it has lead
     
  14. luckydynes

    luckydynes F1 Rookie

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    #14 luckydynes, Aug 20, 2008
    I don't know . . I thought I read that wide plug gaps with hot ignitions can erode the center electrode???
     
  15. fastradio

    fastradio F1 Rookie
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    #15 fastradio, Aug 20, 2008
    OK...At first I thought I was missing something here (looking at your spark plug), but evidently not. I run 12:1 high compression pistons in my BB, an MSD 7-AL2 with .035" plug gaps...and have not seem the problem depicted. However, I have seen angled centered electrodes when using one of the automatic hand-held plug gappers, as they can put side pressure on the center electrode when setting the gap. Are you using such a tool?

    From your picture, the center electrode does appear to be approximately parallel to the ground electrode...Yes?

    Regards,
    David
     
  16. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #16 Steve Magnusson, Aug 20, 2008
    NGK indicates that this is an expected (bad) effect with leaded fuel and their standard electrode (nickel) material -- see "abnormal erosion" and "lead erosion" towards the bottom:

    http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp?mode=nml

    Your photo looks something like the early stage of those diseases IMO (assuming that outer electrode surface wasn't perfectly parallel to the center electrode surface when new -- so it first "wears" on the corner of the center electrode nearest the outer electrode where the spark is occurring and gives the tilted appearance).

    Have you tried a Platinum or Iridium electrode plug for comparison?
     
  17. luckydynes

    luckydynes F1 Rookie

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    #17 luckydynes, Aug 20, 2008

    I have that tool but didn't start using it until I noticed the gaps were crooked when I pulled the plugs . .. I used that tool to "force" the wire parallel to the electrode (as you noticed) when I started closing the gap up . .. so the electrode got crooked before I even bought that tool you're referring too . . I thought it was originally 'cause I had not gapped them parallel with the "tapered" gap style tools but it started happening again with just .03" gap and the "squeeze" tool.


    Is the center electrode that soft that you can deform it with pressure? I figured the porcelain would crack but??? . . maybe a little too aggressive with the tapered syle tool opening up the gap . . maybe I'm deforming it? . . I didn't think they were that sensitive.

    Also my MSD DIS4 is capacitive discharge with Denso coil on plugs . . is the 7AL capacitive discharge?


    cheers
     
  18. luckydynes

    luckydynes F1 Rookie

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    #18 luckydynes, Aug 20, 2008
    Interesting . . thanks for the info . . something to try . .. as always . .. the more I learn the less I know ;)

    cheers
     
  19. luckydynes

    luckydynes F1 Rookie

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    #19 luckydynes, Mar 27, 2009
    just adding some info in a haze.

    I installed NGK 6's at .04" gap and got a miss at 4K and 6K at full throttle ... f'd with the MAP a little 'cause I didn't belive plug gap made any difference from circus posts here ... pulled the plugs .. cleaned with a wire brush (useless????) ... gapped to .06" .. miss is gone ... and there is more power.



    Coil on plug ignition with MSD DIS-4 ... why is this making so much difference and how much plug gap is too much?

    I went to buy -11 plugs with wide electrode gap but tip can't be unscrewed so the coil on plugs don't fit ... meaning .06" gap is massive for std. plugs.

    cheers
     
  20. luckydynes

    luckydynes F1 Rookie

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    #20 luckydynes, Mar 27, 2009
    I never used the plier tool again regarding center electrode distortion which is why I swapped plugs ... probably lead from the avgas?? not happening on all cylinders .. the electrode distortion is happening from fuel/operating conditions/too much gap making spark do weird sheeet/why do I care at $1.50/plug every 2k miles?

    cheers
     
  21. thecarreaper

    thecarreaper F1 World Champ
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    #21 thecarreaper, Mar 28, 2009
    all i can add is i was always told to run a larger gap with msd, and crane ignition systems on these cars, as well as my muscle cars. i ran .050 to.055 gaps using ngkbp5es plugs on my carb 308's with no issues. my QV is all original and runs like a Honda, so i am not messing with it.
     
  22. Artvonne

    Artvonne F1 Veteran

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    #22 Artvonne, Apr 3, 2009
    I was told 100 years ago to always make the outer electrode perpendicular to the center one to maintain even wear, to never leave it bent at an angle. By being angled the spark will always be drawn to the narrowest gap and thats were all the erosion will occur and it will run excessively hot at that point. But I never seen an effect of it in all that time. Not saying thats the cause, but I have never gapped plugs without making the electrode flat.
     
  23. luckydynes

    luckydynes F1 Rookie

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    #23 luckydynes, Apr 4, 2009
    I was making sure to do that and still saw the electrode start leaning. In one of the original pics you can see how I deliberately bent the wire parallel.

    It's a PITA keeping the electrode parallel with such a massive gap on plugs that are not "-11" that's why I know what the electrodes were like when they were brand new. Plus follow along with me on this.

    What you're saying would make the electrode wear on the opposite side of where I'm seeing it degrade. If anyting the gap has been tighter on ground electrode side. When I gap the std plugs out real wide in order to keep the electrode parallel the wire is barely long enough to extend all the way over the center electrode ... meaning the side that's erroding has very little ground electrode above it ... meaning the spark has more of a gap to jump to the tip of the ground electrode at a very slight angle. I thought this would accelerate the degradation but what you're saying is opposite ... the electrdoes wear where the gap is tightest? I thought I read the exact opposite in fact ... that wide gaps 'cause plug degradation???

    There's some other plugs I'll try that have the removable tip and "-11" option.

    Thanks for chiming in.
    ,

    Sean
     
  24. Artvonne

    Artvonne F1 Veteran

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    #24 Artvonne, Apr 4, 2009
    I will admit I am no electrical whiz, but my undstanding of electricity is that it always takes the path of least resistance. To jump a wider gap, the resistance must be higher, so the spark would, should occur in the narrowest region. By keeping the gap area as flat as possible, each spark would normally move around the electrode side to side, edge to center, each time picking the next best place but overall burning off material more of less even, creating even wear.

    When the gap area is angled, your forcing the spark to continuously pick one tiny area, and it will always be the narrowest region with the least resistance. It would figure then, that if all the energy is focused to only one small area, that area would run hotter? I dont have enough knowledge or experience to know if this is your cause, but if your not seeing other problems in the cylinder its certainly a good place to start? Remember also that higher compression increases cylinder pressure which also increases resistance. A spark that can barely make the jump at 400 psi is going to fail at higher pressure, or "blow out" as you say.

    As for AV Gas, again I dont have good knowledge with fuels. But I recall stories my Dad has told about his "Rocket 88" Old's. They (my Dad and a guy he worked with) were told to empty the tanks of some aircraft and dispose of the fuel, about 700 gallons of 145 Octane. Well, they scrounged up some 55 gal barrels and each took home half of it. Thats right, Dad had brought some half dozen 55 gal barrels of 145 Octane home and started pumping it into the Olds. They had some new fangled plug out in the 50's with multi electrodes, probably simular to Lodge but with a lifetime warrantee. He claimed the car ran like a bat out of hell but it was burning up the plugs. After the third set the company said they had them "analysed", and though they couldnt determine the cause they said he was overheating them something fierce. My understanding is, the higher the octane the slower it burns, so what can happen is that its still burning long after the exhaust opens and your litterally blowing blue flames out the cylinder. Aircraft engines turn slow enough and have large enough cylinders that the flame is pretty well exhausted by the point the exhaust vale opens, whereas with a smaller cylinder running at higher speed that may not be the case. If its still burning going into the overlap phase its going to get pretty hot.
     
  25. luckydynes

    luckydynes F1 Rookie

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    #25 luckydynes, Apr 4, 2009
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