Originally
on 1500s and 1600's up to R-23723 that were set up for USA
crankcase emission standards. This cap sat on a 2" riser
that had the fitting that the valve cover to air cleaner
hose connected to. Four inch long wire is center is designed
to be soldered to base to keep it from getting lost.
Datsun
Roadster Parts from Rallye Enterprises, Ltd.