What is an end cone in an oil furnace and what does it do?
Also how does a nozzle work? Can it be adjusted? What can make an older oil furnace produce thick black smoke?
This is in the wrong area but I will answer anyway. I answered your ? on the other area. End cone helps create the swirling air pattern for the combustion process.
If you really know how it works, you have an execellent chance of fixin' er up!
Tomorrow is promised to no one...
Look at the nozzel for number one is size the ohter is in degree sometimes they need to be changed depending on flame color this can cause black smoke also check flue pipe this can cause smoke also.