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View Full Version : Electrical: Tach Sending Units W/ Pertronix Ignitor & Coil



Steve L
07-04-2011, 02:50 PM
70 yr old Newbie here with a 53 Commander on a 62 Hawk frame & dash, & a 259 engine. Bought it that way. While under the dash removing the clock and a couple of switches to rebuild, I evidently knocked two partially bare wires from the tach sending unit together. Needless to say, I now have a non working tach. Once the smoke cleared, I crawled back under there & started looking at the wiring. On Sending Unit:
Red: Brings the power from the Ig. switch
White: Goes to the Tach gauge
Black: To ground
Yellow: Returns from the tach gauge to the 8 plug
Green: Connects to the junction post & connects with the pink resistor wire going to the coil.
Since I felt I fried something in there, I started checking voltages. Had 11.6 at the junction post
which seamed reasonable. Checked the end of the resistance wire at the coil and it had dropped to only 5.3 volts. I thought perhaps thats the reason the car was a little hard starting. Went on the net & got Pertronix instructions which say the resistor wire should be replace by a reg wire & should have 12 volts at the coil. Did that & what a difference. Car starts immediately & seems to run much better. Getting close to my questions. There are two aftermarket senders out there. Stude Int & Studebaker Parts .com. The old threads say both had problems a few years back. Is anyone running one of these units with the Pertronix Ignitor and coil successfully utilizing the full 12 volts & not the resistor wire to the coil? If so, how is it wired? Both of the above are wired differently. Help me get that old tach working again. Can both handle the 12 volts feeding back?

I did pick up one interesting bit of wiring info that would help ease hard starting cars. Run a wire from your starter relay to the coil on any unit that still has the resistance wire or a resistor in the wire to the coil. This will give you a full 6 or 12 volts to the coil only when the starter is engaged. Should give you a much better spark at the start.

StudeRich
07-04-2011, 07:12 PM
/Cut/I did pick up one interesting bit of wiring info that would help ease hard starting cars. Run a wire from your starter relay to the coil on any unit that still has the resistance wire or a resistor in the wire to the coil. This will give you a full 6 or 12 volts to the coil only when the starter is engaged. Should give you a much better spark at the start.

This is not new news, all 1956 and later Studebakers and all others with 12 Volt systems (including all Fords) are already wired somewhat this way. The 12V Solenoids all have the "I" (Ignition) small terminal as well as the small "S" (Start) terminal on them accomplishing the same thing. :)

Steve L
07-07-2011, 06:00 PM
Well, lacking a response to my question, I called & talked to the people at Studebaker Int.
They were also unsure, so they called their supplier that makes the unit. The answer came back as a yes it will work with the Pertronix coil & ignitor. It was stated many customers use this combination.
The sender counts pulses and sends them to the tach. It doesn't care whose unit creates the pulses.
So, I ordered one. Will post the result when installed.

Steve L
07-29-2011, 01:10 PM
Better late than never. I ended up ordering the tach sender from Stude Int because it was wired like the old one. (800009) Got one like the one sold by Stude Parts.com, so there is only one replacement type out there now that I could find for the 1962 rectangular Hawk type. The nice part is it works, but you have to wire it differently. Wire it the same & you will burn it up. **The blue wire goes to the negative side of the coil.** Brown wire goes to the brass terminal on the tach. Red wire goes to 12 volt ig. switch. the white wire goes to ground. You will also need to run another ground off the tach steel terminal to ground. This is in addition to the one already there for the tach light. This unit had some jumps to it so it has a problem handling a full 12 volts to the positive side of the coil. Felt all my grounds were good. Called Pertronix technical dept to ask if I should reducd the voltage going to the coil. They said they would rather add a 10k-Ohm 1/2 watt resistor to the blue feed wire going to the tach sender. Did that & it did improve the stability. Still a slight jump at idle, but seemed smooth above 800-1000rpms. It has a potentiometer (sp) that allows for fine tuning, so seems to work pretty well.

Found info on Bob's site that was very informative. http://]www.studebaker-info.org/tech/tach/tachpert.html[/URL] Shows the insides of the old unit & even how to rebuilb it if you are so inclined. I was thinking about that until I saw how small the wires were. Even tells you how to test your tach with a 1 1/2 volt battery. Hope this helps someone. Thanks 64VK7 for your info. Appreciate it.