I can only "see" exhaust fumes in certain light. 99% of the time the fumes are invisible. If i had to guess I'd say the fumes are white or grey. The truck does smell kinda bad when it runs and it doesn't have a rough idle, but it doesn't idle consistently.
The timing was retarded by about 10 degrees for a few months (it's correct now), but it was much more easy to tune the carb this way. Now i have to run it rather lean just to keep it from idling at 1200-1300, even with letting letting the idle adjustment screw almost all the way out. I've been trying to get it to idle around 750-800 but it only wants to do 500 or 1000. I guess what i'm trying to say is that it idles smooth, it's just that the rpms usually don't return to the same spot. i.e. it usually idles around 1k, but also will idle at up to 1300 or as low as 450.
Also, the cold idle screw has had absolutely no effect on the truck since i've had it running.