My tach is stuck at 3000 rpm. I assume this means it is internally faulty. Should I start searching for a replacement tach or is there something I can do with this one? Also what tachs interchange? Our car is a 1971 series one 240.

Did this start happening suddenly? It sits at 3000 even when the engine is off? Unless you can tap on it somehow to get it unstuck you're going to have to remove it from the dash - whether you fix it or replace it. Be aware that the car won't even run without the tach ...

Mike is right, without having the tach plugged in, the car won't run (unless you hot-wire it). There are two types of 240Z tachs, known as three-wire and four-wire. They are not easily interchangeable. As I recall it, our Series 1 cars use the four-wire version. So I think you'll need to stay with a '70-71 tach - a '72 or later probably won't work.

We just bought this car and the tach was not working when we bought it. I plan on installing electronic ignition soon (pertronix). Will that make a difference on tach options? (possible use of later model tachs or aftermarket) I do have a tach from a 1972 car. Would that work. Where do I look for the number of connections? on the back of the tachometer itself? The car currently has an automatic with dual points.

Yeah, look at the back of the tach to see how many terminals it has - 3 or 4. I believe that the '72 tach is different than the early tach, though.

The tach issue shouldn't make much difference to which electronic ignition you end up using, but I would strongly recommend not attempting to do the EI upgrade until after you figure the tach thing out. Trying to fix the tach after the upgrade could be much more complex.

On my car (same 10/70 production date) I went with a 280ZX distributor with electronic ignition, the hook up to make the tach work properly with that ignition was fairly simple.

Have the same problem with my tach. It is stuck at 1200. Bought a four wire to replace it.

got a 260/280 infront of me (sticking when hot) it has 3 wire connections on back, 2 to the plastic insulator terminals and one to the brow phonelic connection.

I verified that my 10/70 car is the four wire tach.

The 71's and 72's use the same tach. The 73's had the different prongs.