Any crankcase vent system needs to draw fresh air in an expell blow - by gasses, a single vent cap won't do very good job. Get a road draft tube at least. Modify to PCV, not that hard and helps keep crankcase dilution way down. Factory PCV was useed on many 261 truck engines as wall as 235s in forward control bodys and optional on others. I cut the downpipe off an old road draft tube & welded a washer to accept a grommet and PCV valve.
BC
Good looking rig you got going!


BC
1960 Chevy C10 driver 261 T5 4.10 dana 44 power loc
1949 GMC 250 project in waiting
1960 C60 pasture art
Retired GM dealer tech. 1980 - 2022