Only one spart plug carboned over...what would cause that? (update)

[AKcharger]

He's one for ya' I cleaned a set of plugs installed them ran the engine 5 min and one plug was coated in black carbon soot (not oil) all the others were fine. Could the carb "select" one cylinder to go mega rich or does it sound like an ignition problem?

[firefighter3931]

More than likely it's ignition related. Bad plug, wire or cap.


Ron

[471_Magnum]

Could also be an oil leak, either from the intake manifold seal, or piston ring.

My old 451 would foul the #1 plug after about 100 miles due to a bad oil control ring on that piston.

[Plumcrazy]

What did the plug look like that was in that cylinder before you cleaned them ?

[TylerCharger69]

being black, and sooty  that fast....I'd say you have an oil leak...leaking into the cylinder   through a valve seal or ...i hate to say this....but your rings!!!

[AKcharger]

Plugs were OK except #4 cylinder that plugs was black...but not oily/or wet...looks like it was just mucho rich

Well don't want to think it's rings but like I said above wouldn't oil be wet and ...well...oily?

[TylerCharger69]

If it's a lot....yeah   it'll be wet.   But if it's just a little...it will be sorta sooty.   being sooty  tells me the cylinder is firing.  I cant see one cylinder being rich and not the others.   Are the other plugs tan in color?

[RD]

maybe you didnt have the spark plug gapped properly, hence it was not providing a good enough spark to burn efficiently?  Check your distributor cap and the coinciding point for that cylinder to see if it is corroded or shows evidence of premature wear.  Also, check your spark plug wire (ohm test it and compare it to at least two other wires).

[firefighter3931]

maybe you didnt have the spark plug gapped properly, hence it was not providing a good enough spark to burn efficiently?  Check your distributor cap and the coinciding point for that cylinder to see if it is corroded or shows evidence of premature wear.  Also, check your spark plug wire (ohm test it and compare it to at least two other wires).

Like i said above it's ignition related. Carbon on that plug means it's not firing properly for whatever reason.....this is based on the fact that all the other plugs are clean. Could be the plug, the wire or the tower in the cap that corresponds to that cylinder. Like jamey says, get an ohm meter on that wire and measure for resistance. Check the cap and replace the plug.

On a somewhat related note : a friend installed new plugs on his son's car this past week and afterwards it had a misfire. Turned out one of the brand new plugs was defective. It happens....

Ron

[AKcharger]

Yup, I think you guys are right, let me take a look and I'll let you know how it goes

Thanks

AK

[AKcharger]

Well, with ignition and fuel good I thought it might be the valves. I pulled the valve cover and when I did saw metal chunks I thought ..."not good". We pulled the Jug off today thinking it was a carboned over valve then broke some of the valve train an was partially right, a lifter catistrophically came apart, that was the metal hunks. And since the lifter would lift the exhaut valve would not open all the way.

Problem is the lifter is installed when the engine case is put together so only way to get that bad lifter out is to split the case which is major maintenance. So for lack of a $40 lifter we'll have to get a $19K engine.


Oh this was all about an airplane, did't say that at 1st since I thought people would shy away from offering advice, but an engine is an engine.

Thanks

[firefighter3931]

Oh this was all about an airplane, did't say that at 1st since I thought people would shy away from offering advice, but an engine is an engine.

Thanks

That is sneaky AK 

Glad you've located the problem. 


Ron