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When i had Pertronix electronic ignition installed by Hotrods and Custom Stuff, my tachometer stopped working on my 1968 442. Yesterday when I pulled the distributor...I saw a group of wires taped up and tied to the smaller wires that go to the starter solenoid. One of them had a copper wrapped around the outside of the brown cable. The replacement tachometer cable I purchase is brown, has the same end connector, put doesn't have the copper around the outside. I presume one or both of these brown wires control the tachometer..can anybody assist in identifying each of them?
My initial reaction was, why didn't you ask the shop who did the work to get the tach working after they screwed it up?. From the factory there were two wires that went to the "+" terminal of the coil, the resistor wire that applied 9.6V when the key is in RUN, and the bypass wire that applied a full 12V when the key was in START. Electronic conversions can either accept the 9.6V or will require it to be replaced with normal copper, but that depends on the specific conversion kit. The tach lead attaches to the "-" side of the coil. The factory tach lead is a copper wire with an overbraid that is grounded to prevent ignition noise from being picked up by the radio. Where's that third wire?
My initial reaction was, why didn't you ask the shop who did the work to get the tach working after they screwed it up?. From the factory there were two wires that went to the "+" terminal of the coil, the resistor wire that applied 9.6V when the key is in RUN, and the bypass wire that applied a full 12V when the key was in START. Electronic conversions can either accept the 9.6V or will require it to be replaced with normal copper, but that depends on the specific conversion kit. The tach lead attaches to the "-" side of the coil. The factory tach lead is a copper wire with an overbraid that is grounded to prevent ignition noise from being picked up by the radio. Where's that third wire?
Joe...you're right. I should have done that The tachometer was fluttering when I took it in. I assumed there was a problem before I took it there and took a **** when it was at Hot Rods & Custom Stuff. I didn't realize till now they completely disconnected it and tapped it up. Up further inspection...looks like the wire is pretty dirty and possibly the yellow wire that goes the starter solenoid?
The only way to tell for sure is to see if you get battery voltage on the yellow wire when the key is in START. The resistor wire should have about 9.6V when the key is in RUN (unless it's been replaced with copper). I have no idea what that copper overwrap is supposed to be, but it certainly isn't factory. Is this a factory rally pac car? If so, the tach wire will have a braided overbraid (not this half-fast wire wrap). If the Rally Pack was added, then all bets are off.
The only way to tell for sure is to see if you get battery voltage on the yellow wire when the key is in START. The resistor wire should have about 9.6V when the key is in RUN (unless it's been replaced with copper). I have no idea what that copper overwrap is supposed to be, but it certainly isn't factory. Is this a factory rally pac car? If so, the tach wire will have a braided overbraid (not this half-fast wire wrap). If the Rally Pack was added, then all bets are off.
It's a factory rally pac car...nothing was changed by my father-in-law. I'll test the resistors wire. Thanks Joe!
March 11th, 2024, 10:10 AM
