My 1931 Model 10 came without an oil pressure indicator but had an oil pressure gauge attached via an elbow just where my foot was likely to knock it off - quite apart from being tricky to see whilst riding along at great speed. The indicator seems different to other models, having a 7/16" 26 tpi attachment to the timing cover so I thought I'd make my own.
Progress so far:
(http://i43.photobucket.com/albums/e398/iansoady/bike/Sunbeam/oil%20pressure%20indicator/IMG_2229_zpswa4s7o92.jpg)
(http://i43.photobucket.com/albums/e398/iansoady/bike/Sunbeam/oil%20pressure%20indicator/IMG_2227_zps7u5jlaat.jpg)
I have yet to ream out the main bore (to a nominal 5/16") and make the piston / indicator rod and work out a sealing mechanism. I'm inclining towards a brass piston with a PTFE disc attached but have yet to decide on the details. I'll make it so that the indicator is flush with the outside face of the outer hexagon at rest so it's obvious when it starts to move out.
I must say I have some doubts as to how well the pump will pull the oil up from the oil tank under the crankcase.......
Just thought I would post the finished article:
(http://i43.photobucket.com/albums/e398/iansoady/bike/Sunbeam/oil%20pressure%20indicator/IMG_2278_zpse4jbljbh.jpg)
although I have remade the piston / rod component (now out of alloy) as I wasn't happy with the finish.