Spark Plug Read

[troutstreamnm]

These plugs have only 850 miles on them in a fresh motor.  They are light brown in color and already have carbon deposits forming on the base.  These are Champion RJ12YC plugs.  Do you think these are running too cold or typical of a break in period?  What is your analysis you recommendation?  Thanks

[vinb]

The color looks ok, but it's hard to tell if they are starting to oil or is that fuel..(look little wet)
Heat range seems to be ok 12's is what the factory called for...
Just for the heck of it if you have a leak tester, leak the engine and see what kind of numbers it has.
You only have 850 miles on it,  I would drive it some more and get more miles on it....

[6packCuda]

  This should be obvious but, have the heads also been re-worked (valve guides, seals, etc.)? If not, you could have some extra oil coming down the valve guides and burning in the combustion chamber. It amazes me how many people will put an old crappy pair of heads on a fresh motor without touching them, then they can't figure out why their fresh motor burns oil.

[troutstreamnm]

The heads were worked on too so that should not be an issue and the engine is not burning oil.  I believe the moisture was fuel and not oil.  It does seem to be running rich even after going 8% lean on the jets (I live a 5500 ft amsl).  I think I'll go ahead and run these longer and see what they look like at the next oil change.  Thanks 

[bb71challenger]

I agree it looks like its running a bit rich. I cannot tell for sure but what is the gap? the plug on the left looks to have a tiny gap but it might just be an illusion. Does it bog or anything when you punch it? any sign of black smoke at all?

[Chryco Psycho]

looks Ok to me , the center ceramic is light brown so you are in the zone , you need a O2 sensor to really dial it in perfectly

[Supercuda]

The color doesn't look bad, but it might be a little rich. No obvious signs of over-fueling showing on them yet, but the deposits on the left plug look a little shiny. This can be caused by additives in the gasoline, or by other things that we are not aware of. What carb are you running? What ignition system? Most electronic ignitions can stomach a wider gap, and often work better with one. The Chrysler electronic ignition responds well to a gap of .045" at the spark plug, and experimentation with your engine may yield better results with a gap as wide as .060". What is your compression ratio? This also affects ignition performance, and fuel requirements. Your camshaft will also affect these tuning parameters, and knowing what brand and octane of fuel you are running will also be helpful.

[moper]

They look very rich to me. I don't like to see anything wet up the threads, and there's a lot of carbon there. Thye look like victims of a weak spark, or a choke set too rich. 850 miles should be clean, with that tan color on the porcelain. Did you let this engine warm up before you pulled the plugs? Or just back it out and pull them with it cold?

[Chryco Psycho]

Well he is already what 8 jet sizes smaller which is the edge , don`t want it too lean
 I never go past .045 for gap as it is too hard on wires etc

[troutstreamnm]

The car had been at rest for a week or so before I pulled the plugs.  I'm running a Mopar electronic ignition with an orange box and an Edelbrock 750 cfm 4bbl carb.  It has forged TRW pistons with 10:1 compression and a .484/284 cam.  It is certainly a thirsty beast for a 383, but it makes nice power.  I'll try increasing the gap to .045 and it is very likely the choke needs adjustment.  Thanks for the comments!

[moper]

CHeck the voltage at the coil positive with the key in the "run" position. If it's lesss than 6-7 volts, there may be an issue with the wiring in the ignition primary circuits. If you're at 5500feet, it may still be way rich. Those plugs look rich, but if the ignition is weak, it would explain the look. Also, if the ignition is weak, going tighter on the gap will help more than going wider.

[troutstreamnm]

Thanks Moper.  The entire electrical system is basically new, but I'll double check the voltage as you suggest.  I think the problem has been running the choke too rich.  I had to adjust the choke back quite a bit so that is a likely culprit.  Guess I should have check that out with the new carb sooner.     Set the plug gap to .045 too so we'll run it a while and recheck.

[Aussie Challenger]

  I would say that is oil burning looking at the plugs, however have you bedded in the rings, have you been doing a lot of idling or light throttle work. It may be that you just need to take the car for a good drive, don't go doing burn-outs but give the rings a chance to bed in properly.   

[troutstreamnm]

Yes, lots of easy miles with a fresh motor, rebuilt transmission and new ring/pinion set in the differential.  The rear end was the last thing to get rebuilt and it has about 600 miles on it now.  Probably can start running it a bit harder. 

[Aussie Challenger]

Yes, lots of easy miles with a fresh motor, rebuilt transmission and new ring/pinion set in the differential.  The rear end was the last thing to get rebuilt and it has about 600 miles on it now.  Probably can start running it a bit harder. 

  This is my point, you may have nursed the motor too much and not bedded the rings in. On your first drive you need to load up the rings a few times to force them to bed in on the new bore surface. The bore can become glazed and the rings won't bed in at all.
  I usually get into top gear about 30 to 40 mph then open up the accelerator fully with my left foot lightly on the brakes allowing the car speed to rise to about 55 to 60, then slow back down and repeat the process a couple of more times. A tall hill can do the same as using the brakes, if it is an auto you have to try and keep it in as high a gear as possible and not kick down so it doesn't rev too high.