My 13B seems to have pulled oil pressure from a small port next to the oil filter plate which supplies the oil to Tracy's PSRU.  A VDO pressure sender will fit into the hole but will not thread so I must assume this was never tapped out for NPT and is still in metric.  In looking at a picture of the engine before I removed all the senders, it shows a small brass fitting on the end of the pressure sender but I can't find that small brass piece anywhere and was therefore wondering what the sock thread size so as to get something to adapt to my VDO sending unit?  Thanks for any help.

 

Doug Lomheim

RV-9A, 13B, FWF

OK City, OK