Black soot from tail pipe

[KrazyKuder]

I have a ‘70 Bronco and I’m getting black soot out of the tail pipes every time I start the engine. I notice it especially on cold starts because it’s spraying everything in my garage. Do you know what causes this and how to stop it?

 

[SHX669]

Usually a choke that is set too rich and/or a carburetor that is running rich. But a bad coil could also contribute . Clean air filter ?
What method do you use to start it ? Pump once - twice - pedal down ?
Is your ignition system stock/factory ?

 

[Arker]

Most likely running rich, my 69 left a black spot on the wall next to where I park it. Had a leaky float needle causing fuel to drip from the boosters.

 

[KrazyKuder]

I have a carb and when I start it I pump the gas 2 times then turn it over. I let it idle for about 30 seconds then hit the gas again. Air filter is new. I also use premium gas, should I go back to Regular? Stock ignition I think.

 

[Arker]

Unless you're running high compression, just go back to regular.

 

[langester]

If the Bronco sits for any periods of time without being run and if your Premium gas is ethanol free I would stick with it. Ethanol has a tendency to cause problems if left in a system too long.
Not much to do with your question but worth noting in my opinion.
Have a good one!