The Stovebolt Site Forums The Shop Area Engine Shop 235 strange draft tube

1947-1954 Factory Assembly Manual
Engine Positive (Crankcase) Ventilation Instruction
R.P.O. 217 Section 0, Sheet 4.00
Two types:
Series: 5000
and
Series: 3000, 4000, 6000

The reason why the engine smokes could be because the crankcase is not ventilating.
To solve the smoke problem you could take the oil fill cap off and see if the smoking goes away or reduces.