Tachometer upgrade

[nahurry]

I’m looking to upgrade my tachometer in my 73. My current tach needs recalibration. Restoration of my tach is between $250 and $350. I’m looking to put a 5” autometer tach in instead. What is the process like to install a modern tachometer?

[SteveJ]

I'm not sure why you think the tach needs recalibration. Have you changed something in the ignition system?

Assuming the tachometer is ready to be replaced, I'll use Speed Hut as an example. Why? I have wired them before, and there are mounting adapters available. See gauge link, gauge adapters, and instructions. Would the Autometer tachometer work with the gauge adapter? I don't know, and frankly I don't care.

Here's an approximate list of steps:

1. Get a 4 pin non-latching 2.8mm connector from Vintage Connections. This will allow you to wire the tach to stock wiring. You will need the male side of the connector. See the photos below for the dash side of the harness. You should also probably get two 2 pin latching 2.8mm connectors for the other wiring modifications. If you don't have a proper crimping tool for open barrel connectors, they have that, too.
2. Use a short piece of 16 or 18 gauge wire crimp the 2.8mm pins to either end.
3. Insert that jumper into the bottom terminals of the 4 pin connector. That will ensure your ignition wiring out to the positive side of the coil stays intact.
4. Crimp the 2.8mm terminals onto the tachometer wires. Install those terminals on the correct sides of the connector. See photos below
5. Remove the two wing nuts holding the tachometer in place, cursing about how small the hands must have been on the person who installed it.
6. If you don't have a dash cap, pull the tachometer out enough to disconnect it. If you have a dash cap, curse the day you or the previous owner installed it and figure out how to get the tachometer past it. (Sorry, no help from me on the dash cap.)
7. As you pull out the gauge, disconnect the bulbs and 4 pin connector from the back of the tachometer. 
8. Cut the socket off the red/blue wire on the lower gauge bulb. 
9. Contort yourself in a strange way to strip about 1/4 inch of insulation off that wire and crimp a female 2.8mm terminal onto it.
10. Strip about 1/4 insulation off the white wires on the gauge and crimp both to the same 2.8mm male terminal.
11. Install those terminals into their respective connectors for when you put the gauge in.
12. Run a length of 16 AWG wire from the negative of the coil to up under the dash. Protect this wire with 1/4 split loom or other durable cover.
13. Connect one end of the wire to coil negative.
14. Crimp the other end of the wire to a 2.8mm female terminal. Note: I can't see anything about a resistor between this wire and the tachometer. You will want to verify with Speed Hut.
15. Crimp a 2.8 mm male terminal onto the yellow wire.
16. Put those terminals into the respective connectors.
17. Attach the connectors.
18. Slide the tachometer into place. Note: I'm not sure about how to secure the tachometer.
19. Program the tachometer according to the Speed Hut directions.

Keep in mind that none of the aftermarket tachometers have turn indicators in the gauge. Speed Hut has them in the speedometer. 

By the time you are done with the install, you are probably at least up to the low side of the cost of fixing your old tachometer.

Why don't you say what your tach is or is not doing? Shoot some video of it. Post the video on YouTube and link it here. We may be able to guide you through a cheaper fix.

[grannyknot]

https://speedhut.com/gauge-applications/revolution-racing-performance/performance-led-tachometer/performance-led-standard-tachometer/4-tachometer-8k-rpm-shift-light-jdm-datsun-z-series/?dd-link=0kx6p31reeb

The Speedhut 4" tach is a good fit for the stock gauge bezel. I can't find my photos atm of when I did it but a few members here have done it. You do have to take Speedhut housing off and modify the stock housing but it is a good fit and looks largely original. Have a look at post #83,

 

 

 

[AK260]

All our Tachs are based on the Smiths ones from what I have read.

This is a useful way of keeping your original face / movement and replacing the electronics for very little money and a tiny bit of soldering. Many have used this on their Datsuns with good results.

https://spiyda.com/smiths-rvi-rvc-conversion-board.html

[nahurry]

My tach suffered a catastrophic failure and is off by about 2000 rpm’s

[Yarb]

There are a bunch of tachs on eBay starting at $40. Well worth swapping out and easy to do IMO. Modifying the harness would be a last resort.

My 2 cents…

[Patcon]

Or buy one from a forum member

[Yarb]

True even better. I was lucky and got one off eBay with no problems.

[nahurry]

A good used original style or a modern tach?

[Yarb]

Original

[nahurry]

Who’s got one for sale?

[Yarb]

Need to go to the classified section here. “Parts Wanted” Create a request for the part you’re looking for. Quite simple.