Motorsports Village

Spark Plugs?
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Author:  Ken0069 [ Thu Jan 22, 2009 12:35 pm ]
Post subject:  Spark Plugs?

Just pulled the plugs out of my engine and man, them things are "toast"?  I've run Accel plugs for years and never seen them look like these Autolite AR3932s?  The whole corner is burnt off of'em and the gap looks like it's about .060?  Started out at like .020 if memory serves.  Never seen a plug do this?  I guess this MSD Digital 7 is acting like a plasma cutter, hey!!  I'll post a pic if I can get one to come out thru a magnifying glass. O:)

Author:  Ken0069 [ Thu Jan 22, 2009 12:47 pm ]
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NO PICS!  O:)  Can't get a close enough shot to be able to see it.

Author:  Beretta [ Thu Jan 22, 2009 12:55 pm ]
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Mail it to me I can get it done....I have a $1200 camera ;-)

Author:  gearhead1011 [ Thu Jan 22, 2009 1:01 pm ]
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check to see if the camera has a macro setting. that will let you get it in focus close up.

Author:  Scott Smith [ Thu Jan 22, 2009 5:32 pm ]
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Just stand back 3 or 4 feet. Then crop the picture.

Author:  jmarkaudio [ Thu Jan 22, 2009 5:46 pm ]
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Keep your plug gaps on the small side, .025 to .030. I've had no issue with the Digital 7 except when I had an HEI ditributor, melted the center conductor. O:)

Author:  Ken0069 [ Thu Jan 22, 2009 7:16 pm ]
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Yeah Mark, I just checked my log and they were originally set at .020, which is what MSD recommends.  I guess I need to look at'em a little more often, hey!  

Anywho, they look like someone took a file and cut a 45* angle on the center electrode where you would normally set the gap.  I mean burnt right off!

Author:  tonyy358 [ Thu Jan 22, 2009 9:23 pm ]
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that is common for a standard plug, combustion chamber temp may have gone up a little.

we had that problem with the ignition on the fict engine. plugs would only last 15-20 hours.

the fix was a double platinum spark plug. and as soon as the platinum was gone it would burn a hole right through the j gap. the platinum plugs had to be changed at 70 hours.

Author:  Hammertime [ Fri Jan 23, 2009 6:27 am ]
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Hey Ken,
Have ran them same plugs several times but only for the nitrous. with issues. A autolite 3910-3911 would be better suited if no spray, also gap mine at 30.

Author:  ron owens [ Fri Jan 23, 2009 6:49 pm ]
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I run the champion c59yc plugs on alky and set the gap at 30 and never had a problem except on this last engine and it closed 5 out of the 8 up had to go and index all of them
I usually always index them but got a little overjoyed and wanted to fire it up that didn't last long.   :-  =;

Author:  oobob [ Fri Jan 23, 2009 8:26 pm ]
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I've also noticed the digital7 being tuff on plugs NGK's here.

Author:  shrinker [ Tue Dec 27, 2011 6:43 pm ]
Post subject:  Re: Spark Plugs?

You have to consider all the gases. You have to consider CO as part of the story of combustion. More CO may mean more fuel was burnt without sufficient Oxygen to go around. A more complete burn of a rich mixture will result in more CO. That's why you have to see the other gasses as well.

Author:  shrinker [ Tue Dec 27, 2011 10:27 pm ]
Post subject:  Re: Spark Plugs?

It seems that you only have a CO meter. You can still do good tuning with that and plug reading and seat of pants testing. However there is one catch, CO meters will reverse scale when NOx is present. Just dont let that catch you out. What they do is all of a sudden make a relative high speed meter movement to full lean. I say relative because CO meters are slow. Knowing this you can use them for a NOx sensor of sorts. Your mixture is rich, probably too rich for best power in a near stocker. You could probably clean up the cruise and fiddle with the high load enrichment device of your carby and still get good power. It would probably actually make better power that way than now because the engine wont be full of junk.

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