How do I install a tach in a car that did not come with one? How difficult is it?
A tachometer is a great instrument to have in your car. Monitoring your engines RPM will help you shift at the appropriate time to gain the best performance or even better gas mileage. Most aftermarket tachometers only have 3 or 4 wires that need to be connected for operation. A main power wire that gets connected to a 12 volt ignition source, a ground wire, a tach signal wire that connects to the coil or the designated signal wire in your cars wiring diagram, and sometimes a wire to run the light inside the tach for night time use, which can be connected to the same power source as your other dash lights. If your car did not come with a tach, but it was an option for your specific model then there is a good chance the wiring is already in place to run the tachometer. It is best to purchase a factory service manual and carefully study the wiring schematics to determine if the wiring is there or not. The only tools you will need for this wiring job are a pair of wire cutters, a pair of wire strippers, a good pair of wire crimpers, some crimp-on style electrical connectors and a little electrical tape. While this is a pretty simple job, if you are not comfortable using these tools it is best to seek professional help.

If you are trying to install a late model gauge cluster, including a tach, into an older model car that did not have one the process is a little more complicated. You will need the wiring diagrams for both the donor vehicle and the car you are installing the gauge cluster in. You will then have to carefully trace and mark each wire to determine what it is for. Finally you connect the appropriate wires together (temp gauge to temp sender wire etc.) and carefully tape off any wires that are unused. Because modern cars use have varied computer controlled components it is not always possible or compatible to swap gauge clusters so it is important to research the subject for your specific model before taking the plunge.