need help ! trying to get my oil presure gauge working it has not worked since moter swap 305 fuely to 350 carb its the only gauge that aint workin tryed to hook it up with the old sending unit and still nothing it drives me nuts got 2 aftermarket gauges in the car a tach & oil presure want to get all the factory gauges working ---would the factory tach have to be hooked up for the oil presure gauge to work--- or ????what

Does the gauge needle go to the high end of the gauge when you turn on the ignition? If it does try grounding the wire that is supposed to go to the gauge. It should then read zero pressure. If it does that means the sending unit is bad and you need a new one. Otherwise there is something wrong with the wiring.