Ok, I'm finishing up my A-V8 with a 51' flathead. I wired it for 12V neg. ground, and the local auto parts store gave me 'newer' temp and oil pressure senders that matched the thread sizes of the original ones I took from my flathead. My gauges come from an old Paystar gravel truck, and they worked fine in that truck. I installed everything in the car, but the gauges don't work at all. Tonight, I tested the oil sender and found this: With the engine off, the sender is not grounded. When I start the motor, the sender unit sends a ground signal to the gauge. is this sender for some kind of idiot light? If so, wouldn't it be wired the opposite way? Also, the temp gauges are grounded with the engine off, and nothing cahnges een when they get really hot..... Any ideas????
PM me your e-mail addy and I'll e-mail you back about 14 pages, straight out of the manual, of how the Ford/Merc/Lincoln gauges and senders work. Newer senders will not work with the old dash gauges.
You need the senders from the truck that the gauges came from. If they were 6V then you'll need to reduce the voltage for the gauges. I spent a lot of money trying to cure a hot running engine in my 58 Ply. I was using the 63 383 sending unit with my 58 gauge. Finally I swapped the 58 sender into the 63 engine and lo and behold it was running at normal temperatures all along. The sending unit has to match the gauge. They are not generic.
The Jalopy Journal
