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| Cylinder number 6 spark plug black https://slantsix.org/forum/viewtopic.php?t=61507 |
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| Author: | sdowney [ Tue Aug 15, 2017 10:01 am ] |
| Post subject: | Cylinder number 6 spark plug black |
[url][URL=http://s669.photobucket.com/user/rambler_360/media/IMG_0941_zpsu5r9qw3m.jpg.html]  [/url][/url][/quote]Here are the autolight 66 plugs I replaced with NGKs. They are in order from left to right 1-6. Number 6 is black, what could be the reasons and or corrections I should do to correct this? Could the valves on that cylinder be to tight? Any suggestions or ideas are appreciated. Thanks, Shawn |
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| Author: | Badvert65 [ Tue Aug 15, 2017 11:46 am ] |
| Post subject: | |
One possibility is liquid fuel running down the manifold. Acceleration would tend to push the fuel to the last cylinder. Not enough data to accurately diagnose. |
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| Author: | Joshie225 [ Tue Aug 15, 2017 4:47 pm ] |
| Post subject: | |
Could be a valve adjustment issue. I'd look at excess fuel problems from causes such as a leaky needle/seat, miss-adjusted float or bad float, a bad choke pull-off, etc. All the plugs look like it's running a bit rich, but #6 is absolutely the worst. |
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| Author: | Louise76 [ Thu Aug 17, 2017 9:40 pm ] |
| Post subject: | |
How'bout before you get excited, see how your NGK's run?? Could be just another junk Autolite plug, running "cold". Also, it's hard to get a good "read" on the spark plugs unless you drive it at highway speeds for one straight hour, then immediately pull the plugs without very much city driving to get you back into the driveway. City driving can't get you a good reading on engine fuel/mixture condition. My 2 cents. |
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| Author: | emsvitil [ Thu Aug 17, 2017 9:46 pm ] |
| Post subject: | |
Is it oil residue? |
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| Author: | SpaceFrank [ Fri Aug 18, 2017 9:24 am ] |
| Post subject: | |
All of the above are good points. I agree those old plugs look like you were running rich, but if you just put in new NGKs and it's otherwise running well, I'd give it some time and check the appearance of the new plugs before you monkey with the carb too much. What carb are you running, and when's the last time it was adjusted? I'm not sure it looks like oil burning, but if you're already planning to check valve lash, you may want to eyeball the valve stem seals on #6 while you've got the cover off. |
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| Author: | '67 Dart 270 [ Fri Aug 18, 2017 6:36 pm ] |
| Post subject: | oil or cold plug... |
Is your PCV hose run directly to #6 intake runner? That would be my guess. Brian |
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