Plug really rich or oil

[Gr8polarbear]

This plug only has about 500 miles at most on it. Would you say it is to rich or oil. Car does not smoke at all. When I changed the plugs this same cylinder was like this. Out of nowhere the other day car started to idle rough I am trying to track down why and pulled this plug again and this is what I get.

 

[PRH]

The question I’d be asking myself is……
How would only one plug be showing that “rich”?

An isolated oil consumption issue? That’s easier to grasp.

 

[fishmens67]

Looks like oil to me

 

[Bewy]

Engine specs? Plug heat range? The gasket on the plug looks like it was hardly compressed.

 

[Gr8polarbear]

Engine specs? Plug heat range? The gasket on the plug looks like it was hardly compressed.

383 906 heads dual quad carbs.
NGK V-Power Nickel Plug Number XR5 Spark Plug - 3332. Plugs were tightened to stop and then about an 1/8 to 1/4 more turn.

 

[Heywodja]

Do a compression check.

 

[340six]

As my friend Walter would say looks like earl (oil) to me.

 

[Gr8polarbear]

Compression was 130. Only had time last night to do that one cylinder. Looks like it time to get heads sooner then intended

 

[Daves69]

What's the condition of the rest of the ignition system?
(Plug wires, cap, etc.)
Basic plug reading.......

 

[Gr8polarbear]

Cap looks pretty new. 6al and it has a box coil both are older but the spark that comes out it crazy strong. Plug wires are older but in good condition just a bit dirty. I have been wanting to upgrade the heads looks like a good time to do it.

 

[AJ/FormS]

I highly recommend a full 8-cylinder compression test and a Leak-Down test as well.
If all 8 are 130, then yur 383 if normally aspirated, has a design impediment.
If that plug comes out of a cylinder, that is connected to an intake runner, that is, by itself connected to the PCV that is an engineering problem, reroute the PCV to where it belongs.
Or if the associated intake runner is connected to the brake booster, that is just laziness, reroute it to the Plenum, to where it belongs, with a vacuum-rated hose, AND, check you brake-fluid reservoir. If it is very low, yur gunna need to suspect a ruptured diaphragm.
And finally, check your crankcase for vacuum, with the PCV defeated. It may be that the intake gasket for that cylinder is sucking oil out of the Valley, oh wait, you said 383, never mind, lol.

 

[Bewy]

Plug heat range is correct. But oil is getting into the com chamber. In view of the low comp test reading, probably worn rings. Can also be worn valve guides. New spark plugs will just continue to foul.

 

[MOPAROFFICIAL]

That cylinder is sucking oil
Stem seal or oil past the rings.
Fluke would be a crack. Your intake is isolated from oil, so...

 

[Gr8polarbear]

I highly recommend a full 8-cylinder compression test and a Leak-Down test as well.
If all 8 are 130, then yur 383 if normally aspirated, has a design impediment.
If that plug comes out of a cylinder, that is connected to an intake runner, that is, by itself connected to the PCV that is an engineering problem, reroute the PCV to where it belongs.
Or if the associated intake runner is connected to the brake booster, that is just laziness, reroute it to the Plenum, to where it belongs, with a vacuum-rated hose, AND, check you brake-fluid reservoir. If it is very low, yur gunna need to suspect a ruptured diaphragm.
And finally, check your crankcase for vacuum, with the PCV defeated. It may be that the intake gasket for that cylinder is sucking oil out of the Valley, oh wait, you said 383, never mind, lol.

I was in a bit of a hurry when i tested that cylinder and may not have let it cycle long enough. I did cylinder 8 and it was at 150. I plan on doing a check on all the cylinders so will see what i get. The pcv runs to the rear of the intake right under the rear carb.

 

[Gr8polarbear]

That cylinder is sucking oil
Stem seal or oil past the rings.
Fluke would be a crack. Your intake is isolated from oil, so...

I am thinking that it is the valve seals. I was told that new flat top pistons were put into the engine so should have gotten new rings as well. The heads are 906's and dont see any sign they have had anything done to them.