Originally Posted by
Charles Wahl
That looks less like an oiler than a zerk fitting for grease. I have a 60s Falcon frame that came with one of those, brass, and it had a spring-loaded bearing closure. The top of it was bunged up, but the bottom was in good shape. Like many "plumbing" items, this had a tapered thread. I removed it, and tapped the hole for a metric 5 mm x 0.8 screw, which I plan to use as an oiler (thumb turn in and out). The BB shell is not all that thick, and yours even less so. If it were mine, I'd be tempted to use both holes in the top of the shell, and drill/tap holes into the insert and the shell.
Charles,
Many thanks for the very, very helpful reply. I'd just assumed i was limited to the size hole already there. And the idea of drilling my own holes in the insert really makes a lot of sense - a really neat idea. Thanks again!