Perhaps that 7v circuit was a low fuel light or something?I've started taking apart the instrument cluster I received -- beginning to think about how to mount the tach where temp/fuel gauge are (it will fit diameter-wise and depth-wise) and what to do about a fuel gauge. I've been piddling in the garage trying to bench test the fuel gauge. I have a spare sender but the gauge has an extra terminal. Most have ground, 12v and sender connections. Mine has those -- but also a terminal marked "7V" that is connected through the printed circuit to a similar terminal on the temperature gauge. Gotta figure out what that is/means.
My sender is 5 ohms to 115 ohms. I can't get an aftermarket gauge that matches that -- however, 0-90 ohm gauges are common, and that may be close enough. We'll see. I may be able to mod the sender housing and bend the float arm so that 90 ohms is the upper stop point corresponding to full. And if it only goes to 5 ohms at empty - that'll just leave me a little safety margin of gasoline in the tank.
Also plan to get the timing nailed down and make a first pass at setting idle mixture and re-balancing the carbs. Once that's done, I can borrow my buddy's vacuum pump/gauges and re-charge the A/C. 19 raging ounces of R134.
Does that run through a "slosh module" to help regulate the needle on the gauge? So that way when the rheostat fluctuates in the tank the gauge needle stays constant? Most cars have them. The Fox Mustang has a known failure of them from 87-89. Causes the fuel gauge to go bonkers. Most people replace the sending unit only to find that it didn't fix it.Mine has those -- but also a terminal marked "7V" that is connected through the printed circuit to a similar terminal on the temperature gauge. Gotta figure out what that is/means.