No, that piece is spot-welded together. Some of the older stovebolt engines had a twist-off oil filler cap on top of the road draft tube, but when they moved the oil fill to the top of the valve cover, the top of the road draft was sealed off.
They do have a nasty habit of getting clogged up with sludge. I used to remove the draft tube from the engine with a slide hammer, pour a few ounces of gasoline into it, and set it afire out behind the shop. The sludge would burn to ash, which could be flushed out with a garden hose or more solvent. Nowadays, that would get me all sorts of air pollution citations!
Jerry
