Carbon Fowled Spark Plugs

[Ed in Maine]

I am getting poor idle and some stalling as I come to a stop. It is definitely carbon fowling because after cleaning, the problem goes away. Prior to cleaning, the plugs are coated with black, soft carbon after driving only 200 miles. I would like to try a hotter plug. The plug I am using is Champion W16Y. I have read the excellent information on the "Ford Garage." The next hotter plug is the Champion W89D.

Most of my high speed driving is less than 45 mph. Typical touring speeds are 35- 40 mph. Is anyone using the W89D and is the plug color a light grey? Thank you for your input. Ed

[Kurt in NJ]

too rich?, where do you have GAV set, have you tried closing it more
i recently put some w16y that were black and fowled in my car and burned them to light tan, then put the 3X that burn clean to white back in—- the w16 is a colder plug that a 3x in my car
for me high speed driving is over 60, full advance, gav 1/4 , over 60 it wants a little more gav

[Oldgearz]

I run the cheap Autolite 3076 which is about the same heat range as what you are using, and they burn clean leaving a nice tan color. I agree you may just be running too rich. Maybe try running GAV at 1/4 turn and see what happens.. These old engines are all different and different results should be expected for similar conditions. Make sure your choke is fully open when GAV knob is fully down.

[bobbader]

Ed, you have been posting for quite some time yet this is the first time you've commented about this. It begs the question ................. have you changed anything in the fuel or ignition systems recently? Carb new or recently rebuilt? Distributor new or recently rebuilt? Or, have you just gotten the car on the road so that this is your first 200 miles? This info might help diagnose the situation.

[Synchro909]

Does the engine use oil?

[Richard Knight]

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I would go to W18.

[Doug Linden]

I agree with Rick, the W18 is equivalent of the 3X plug. I used the W18 for many years.

[Jim/GA]

The black carbon on the plugs is likely a symptom of the real problem, and not the problem.

The engine is running too rich OR the spark is not hot enough. The fuel is not all being burned, so you get the carbon. Fix that first.

If running an air filter, take it off. Test drive.

If you can cold start the engine with the GAV fully closed, the carb jets are too rich or the float level is too high (or both). I see this all the time, especially float level too high. You can actually set it 1/16" to even 1/8" lower than the published values and it will run great. Stalling on a hard stop is another symptom of float level set too high. You must check and set the "wet float level", not rely on dry.

After getting the carb sorted out, if it still runs poorly, check the polarity of the coil. I find about half the cars I touch with the coil wired backwards. This will give you a weak spark. Also check the point gap. As the cam follower wears, the points close. It can happen very quickly if you forget to lubricate the ignition cam with a little cam grease (or petroleum jelly). The small point gap can give a weak spark.

Having said all that, I do like the Champion W18 plugs. They are good.

Good luck. Let us know what you find.

[bobbader]

I agree with Jim/GA. It's not the plugs. Moving from a W16Y to a W18 will not solve the problem. Folks but every different spark plug that's available on the market without regular complaints of issues as outlined here. I'd lean toward the flow of the jets (or combination thereof) for running rich OR inefficient spark. If you recently serviced or rebuilt the carburetor, is it possible you installed the removable GAV seat instead of the compensator jet in the rear of the main float bowl. They look very similar but the GAV seat has a much larger orifice and will feet way to much gas into the secondary well, affecting the idle and cap jet feed.

[jeepguy1948]

I had that problem and, long story made short, it was the air filter.