Wire colors / tach

[ChrisZ]

I need wiring colors for my -73, it is about the wires at the ballast resistor / coil, on my car there is 3 black / white wires and that dont mach up with the FSM diagram, anyone having a photo of those wires from a -73 or a diagram with the right color codes.

My tac is not working and i like to make sure that the wires is connected correct, this car have a lot of bugs.

Chris

[ChrisZ]

Come on guys, isn't there anyone with a -73 that can help me out here ?.....

I pulled my tach today (3 wire) and hooked it up directly, it worked so there must be some wiring gremlins someplace.

Here is some photos:

#1 shows the backside and wire colors, - at the left, + at the right and pulse (yellow) in the middle

#2 shows the wires in the dash harness, 2 blacks at the left/middle is -/+ and the green/white is pulse, it is clear that it dont mach up with the plug on the tach wires.

#3 i have cut the harness open, there is some cut wires and i assume it is from the EGR stuff that has been taken off, notice that the G/W loops in to a B/W that runs to the ballast resistor and the + side of the coil, a 3 wire tach should have the pulse from the - terminal on the coil, the red on the ballast resistor and the black on the - side of the coil runs to my Pertronix.

There is something not maching up here, do i have the wrong tac, did a PO fu.. up my engine bay harness, i really need to solve this, so please help.

I will try to get a better shot at the engine bay tomorrow when it is day light.

Chris

[Bonzi Lon]

This has some good information, http://www.classiczcars.com/forums/showthread.php?t=28449&highlight=pertronix+ballast+resistor.

It appears you leave out the ballast resistor if using Pertronix. I thought you still had the point system.

Bonzi Lon

[70 Cam Guy]

Chris, I gave it a shot with the photos, that's all I have for the moment. I also sent you a PM, hope that helps you too!

http://www.classiczcars.com/forums/showthread.php?p=289572&posted=1#post289572

[ConchZ]

This is from a 10/73 build date car. I've also including a picture of it next to my speedometer, in case you don't have enough to do. A tip from Ron at zclocks.com is to use Maguires Plastic Polish to take out the cloudiness and scratches. This pic shows the cleaned up tac, next to the not yet cleaned up speedo. Big difference. If you'd rather not do it, Ron will do it for you if you ship your lenses to him. I used the polish and a polishing pad on a Dremel to take out the worst scratches, then polished it up the rest of the way by hand. Be careful with the Dremel, as it can heat your plastic up too much and melt it.

[ChrisZ]

ConchZ, are you telling that this is the original tach from your 10/73 Z ?

The confusion gets bigger and bigger, i have a 7/73 and it have a 3 wire witch is supposed to be the "new" style and this is a 4 wire tach from a car build 3 month later !!....

Chris

[ConchZ]

Don't know if its original.

[ChrisZ]

Okay guys, i finally solved the problem by cutting up the harness a the coil / dizzy, after tracking the wire from the tach with a ohm meter, the problem was that when one PO installed a pertronix unit, he cut the wire at that goes from the negative terminal from the coil to the dizzy:stupid:, in that wire the tach wire is spliced in, he should just have connected the pertronix, to the negative at the dizzy and there would have been no problem.

Now i just need to adjust the tach, does anyone know, witch of the two screws on the back of the tach, that is for adjustment and how to ?.

Chris

[70 Cam Guy]

Cool I'm glad you got it figured out! I didn't know you could adjust the tach. I checked the service manual but it didn't mention anything. Sorry man I'm still learning about these Z's so I'm not sure what you can do with it.