I was given a Crane XR-3000 and a PS-91 coil. I was told by several people not to hook it up to my tach, because it will fry it. I called Motorsports Auto today and they said hook it up with the original ballast resistor and it will be fine. I have a 73 (mfg. date 11/72) 240. Is this info right or wrong? I have been told also if you use the ballast resistor with the PS-91 it cuts the voltage to the coil and you don't get the full benefits of the coil, plus could possibly damage it. I don't know who to believe and I know I will get the straight answer here. Thanks

 

The ballast resistor does drop the voltage. I bypassed mine and the tack still works but the coil is a Nissan. There is a resistor in the tack feed from the + side of the coil. Since it is 12 volts to the coil it shouldn't make any difference unless the new sending unit has a terminal for "tack". Just don't use it with the stock tack because it probably uses the - side of the coil.