Burnt tip off plug, what can I expect to find?

Mike Puckett

SCCoA Member
My 1st time trial ran Ok an 13.09 at 106 but my 2nd fell off to a 13.16 at 102, and another 13.26 at 102, and finally a 13.19 at 102. It was definitely laying down on the top end even though my 1/8 mi times were excellent. When I turned the corner after my last one it was missing badly. I went back to my pit and changed a suspect wire to no avail. It drove home more or less Ok albeit on 5 cyls. There were no clanks, clinks, clicks, thunks, rattles, or other mechanical noises, just the minute' crack of a spark on the right side if you got close enough. I just pulled the #1,2, & 3 plugs. #2 & 3 are Ok but #1 had the tip melted back into the plug, the finger was melted off and tip half of the porcelin insulator was gone. Other than the nonfiring cylinder it started up and ran fine this morning and the engine never faltered last night until it started missing at the end of the run, which I won by .04s. There is no coolant in the oil, it's still clear, or visa versa. No odd burnt smells from the plug opening. So the question is, have I done any real damage or should I just replug it and go racing next week. Where did all those little pieces go? Could it have hurt the piston or head gasket with no apparent indication? I wonder if that cylinder is running too lean? Maybe I should pull my chip if it's too lean on #1? Anybody been here before?
 
Ive done it several times..Id do an oil change asap...that peice of pluf has probably shot out yer exhaust or burnt up
 
The plug was one of my NGK TR55-1IX iridium plugs. You can see the little iridium tip imbedded in the melted mess. It made it thru outer space and my engine. When I checked the other side, #4,5,& 6, and they looked so good I didn't bother to check this side. I bet I'd seen some excess wear on it if I had. Well, I sure hope It's Ok. It only popped sligfhtly a couple of times when I shifted gears, which was probably the unburned fuel hitting the hot header. PEP Boys has a special on Mobil 1 so I bought a case this afternoon just to do that with. If I pull my Jerry Chip and reset the EEC it should go back to the rich side if it's leaned out too much.
 
I have burnt a few plug tips off and no harm was done. I had the heads off after those plug mishaps with no scratches or damage. I think they pretty much burn up before they have a chance to tear anything up.
 
Mike,

I burnt the end of the same NGK plug in cylinder #6 after racing a new Nissan 350z on the way to work with 91 octane fuel in the tank. The other side was fine, when I pulled them all to check.

I'll be running Autolites to start this season for comparison sake.
 
Thanks for the info guys. I'll run a compression check tomorrow to be sure that that's Ok. I'm encouraged. The other 2 plugs from that side look fine, light tanish white porcelin and no visible erosion on the tips. I'm still wondering, did the plug fail or did it lean out really bad and if so why. I think I'll change them every race season after this. And, maybe I should unplug the chip and go back to factory rich settings like it was before. It's amazing that these plugs would fire at all either damaged or with the plugwire boot just hanging on it. I ran a 13.16/.19 on 5 cyls!
 
Maybe you hav ean injector problem at that cylinder..Or perhaps it is a cyinder that tends to run lean..Just throwin idea out
 
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