carbon on plugs

[donm]

What amount of carbon is acceptable/typical on sparkplugs? I've adjusted the mixture screw on my 32/36 Weber but, still, pulling the plugs shows black, not the grey color that I had expected because the car does run fine.

[Nut124]

Got a picture?

In general plugs of older carbureted engines will never look like plugs out of a fuel injected engine.

Rich in general runs OK at the expense of some peak power.

Extremely rich can cause valve seat damage and bore wear.

At idle, can you smell unburned flammables at the tailpipe?

[donm]

Nope, no pix; the car is put away until Spring but I don't recall any unusual smells although the inside of the tale pipe seems very dirty. Maybe I should try closing down the mixture screw a bit?

[Nut124]

The mix screw is for the idle circuit only. The rest of the operation is controlled by the jets.

Plug heat range is a factor as well. Plugs that are too cold for the application will always have a black center electrode.

Dirty air filter can make it run richer.

[donm]

Thanks. I know the filter is clean. I think I have Bosch plugs in there now. What plugs would you recommend?

[Nut124]

NGK BPR6ES is the same heat range as the factory plug. Bosch heat range numbers work the opposite way but the comparable Bosch heat number would be 6 or 7.

Google reading spark plugs for mixture. It's quite a science and more complicated than I realized.

[paulwall]

Hi have the same problem really blackened after about 15 minutes.ticks over nicely but sluggish trying to accelerate. Car was running good before went into 2year storage. Has good compression on all cylinders.has the 32 adfa.carb with just the mix screw that dose not seem to be much use will try the plugs mentioned above.

[paulwall]

Also forgot to mention fair amount of unburnt fuel at exhaust pipe. Could my problem be the carb? What could I use as a after market carb.