UL primary chain oiler

[48Flatty]

I've heard various opinions on this topic so...When running a primary belt drive instead of a chain on a big twin flathead, can the front chain oiler metering screw be turned in completely (i.e. shut off) and outlet tube plugged? I am unsure as to if the front chain oiling passages also serve for necessary crankcase breathing/venting. I know from experience that turning off the front chain oiler on a 50s FL results in too much crankcase pressure and oil starts seeping from various places, most notably the pushrod tubes.

[Highlander]

The Big Twin Flathead crankcase breather is in the cam cover as is the 45" Flathead. I believe the primary chain oiler provides oil to the primary via a passage from the oil pump, not the crankcase breather as on an OHV.

[Rubone]

As stated above, yes, it can be shut off completely with zero effect on the breather system of sidevalve engines.

[48Flatty]

Thank you Highlander and thank you Robbie. I can eliminate the "plumbing" I had to vent it and get rid of some mess.