260 tach woes

[racer88]

Hi everyone

I have a 74 260 and the PO for reasons unknown has removed the resistor in the blue wire that supplies the signal to the tach from the coil. I have searched with no luck for the value of that resistor. Does anyone know what that value might be. I would like to hook up the tach but do not want to fry it, and the chances of finding an original replacement here in southwestern ontario are very slim. Any help would be great.

Thanks in advance

Bob Morris

[geezer]

I scrolled to the bottom of this page to "Similar Threads" and found what I think you are looking for. Here's a link to the specific post.

http://www.classiczcars.com/forums/showpost.php?p=210766&postcount=8

[zKars]

I confirm that it is a 2.2K ohm resistor, 2200 ohms. Get a 1/2 watt resistor.

Jim

[racer88]

Yahoo!

Thats great! There is so much great tech info on this sight, it is some times overwhelming to find what you are looking for. I will pick one up tonight and give it a try. Thx Jim and Ron

Bob

[geezer]

If you find the tach is defective, give me a shout. I have one available for the cost of shipping, or free pickup, just down the road in Windsor. Good Luck!

[racer88]

Thanks Ron. I am off to a hockey tournament this week end, so the car will have to wait untill monday. I will let you know how the tach works. All my buddies that I raced stock cars with for over 20 years have street rods or muscle cars so I am the black sheep of the group. Guess I'm gonna have to open some whoop-arse on them this spring when I finally get the Z on the road

Bob:laugh:

[tlorber]

Sorry to hijack, but I am trying to determine if my dancing, incorrect tach is at fault, or if it is an in line resistor. This is for a late 240z (7/73).

Assuming the wiring diagram will attach, does anyone know the actual location of the resistor in the red circle on the diagram? It is on the diagram just right of the ignition coil.

Thanks.

Edited January 12, 2010 by tlorber
error

[ChrisZ]

Todd, it depends on if you have a 3 wire or 4 wire tach, being it is a late -73 i guess it is a 3 wire and i haven't found a correct wiring diagram for that specefic model, i think you will find the resistor in a 260Z wiring diagram, the resistor in the diagram you have attached is as far as i know the ballast resistor.

Chris

[tlorber]

Thanks, Chris.

I see that you have one of the 4 roadsters in Denmark. You are probably aware of the annual roadster meet we have in Solvang, CA.

http://www.solvangshow.com/index.htm

I guess every day is Solvang day for you.

[ChrisZ]

Yeahr, what a romance, ha.

Yes i'm aware of Solvang, i actually have the only low wind shield here, most of the car that is.

Chris

[alhbln]

Todd, it depends on if you have a 3 wire or 4 wire tach, being it is a late -73 i guess it is a 3 wire and i haven't found a correct wiring diagram for that specefic model, i think you will find the resistor in a 260Z wiring diagram, the resistor in the diagram you have attached is as far as i know the ballast resistor.

Chris

Tlorber, could you describe how the tacho behaves (e.g. is the dancing at specific RPM areas or already after switching the ignition on, does the incorrect display happen over all the RPM range or only at specific spots?).

The symptoms could either indicate a defective tacho driver circuit or an incoming signal with a voltage level which is too high.

If your tacho is indeed defective, i am happy to do a repair and calibration for the cost of the spare parts (if the magnetic coil for driving the needle is still intact, then it should be no problem) but you would have to send it to germany.

[tlorber]

Alhbln,

When I turn on just the ignition switch, the tach goes to around 1000 rpm. At idle, the car shows around 2500-3,000 rpm and tends to run around 3-4k above actual (hard to know the exact number). It seems that it gets worse with heat.

Would the parts to be replaced typically be the resistors? Many of them do not test at what their color coding shows they should.

I know that tachs going out are a common problem. Maybe we here could do a group buy and fly you out our way.