Originally Posted by Skooter
I'm interested to what extent the idle mixture screw can help with the soot. Seems to be worse after replacing the Rochester B with a Carter on my 216, as evidenced by the black spot on the garage floor. All parts stock for the 216 in my case but since it's closely related to Dusty's question will tag along here. To be honest I've never even touched the Carter's mixture screw, so probably should do that. Runs great with it otherwise though.

My truck leaves the same mark, and I’ve done all kinds of tinkering with the idle screw. I’ve decided it’s just a thing upon initial startup, and likely not a big deal. Others can chime in if they see it differently.

1951 3100