Hopefully this helps others in the same predicament as I was. Through the years I had collected a NOS set of early Sun gauges and squirreled them away. When I built my '31 and installed them 2 gauges gave me fits. The elec water temp and elec oil pressure. While the sender for the temp gauge had the same values as a Sunpro (now Bosch) sender, it was 1/8" npt and wouldn't read properly as it wouldn't be in the coolant stream with the 1/2" npt adapter I had to use. Eventually I found a 1/2" npt Faria 90404 sender that did the trick. Now, just the oil pressure to go. I finally bought a cheap potentiometer and measured the resistance required at 0, 25, 50, 75 and 100 psi to determine the limits. While pretty much everything nowadays in aftermarket is 240-33.5 ohms, documentation on old Suns is beyond rare (as are the original senders). In testing this gauge it turns out I need a 76-10 ohm sender. I never threw out the old gauge reference materials I collected through the years and dug them out. There's only ONE supplier I could find in my listings that still made a 76-10 sender. If you are running an early Sun 1005 electric oil pressure gauge, you'll need a Datcon 02505-04. If anyone knows another manufacturer that makes one in that range, post it up. Hopes this helps keep some of the old Suns on the road.....
The Jalopy Journal
