I have a Pertronix ignition in my 70 E Type, Series 2. The previous owner connected the red and black wires from the new distributor to the coil, and connected a single black wire from the wiring harness to the positive side of the coil. The black and white wire are left hanging, covered with electrical tape, The car starts and runs, but the tachometer doesn't work. I have power to the three pole plug behind the tach, but it doesn't move. Petronix said I may need a resistor, but I don't understand why it doesn't have some movement, even a high reading of revolutions. Any thoughts or inputs?

 

Well, the white should be the feed from the tach , BUT depending on what country and vin number some had ballast resistors.
That all goes away with the petronix.
So try the white to the positive post of the coil or the same as the red wire.
If you see smoke pull it......

 

"If you see smoke pull it"...good one, but I thought with Lucas electrics you look for smoke to confirm that its working.

 

The 1970 series2 XKEs had a white coil of wire inside the tachometer this is what drives the tach to make it count the RPM it is driven by the pulses that go through it NOT by reading from the white output wire on some tachs and distributors ! So therefore the power for the distributor must come through the tach to make the tach work. Hook the red power wire of the pertronix to the white wire coming out of the tach. If you follow the path of the power flow it goes key-on white wire to tach, white wire from tach, red wire input to pertronix, then black wire to coil.

 

Thanks! That's the info I needed,
Jim

 

Did it work mate?
Should have.......
Good luck
GTJOEY1314

 

No luck; I'm going to track down the original wires to see if the previous owner added something or if there is a break in the connection.