Tach problem

[Don_R]

any difficulties in swapping my mechanial tach out for an electric one from a later spit.

My mechanical tach swings wildly. Checked the cable and things look good. My thought is that the guts in the tach are bad

 

[Andrew Mace]

If you've a 1973 or 1974 Spitfire, it should be pretty much no problem, as the faces will match. But is the cable well (yet sparingly) lubricated? Kinked? New (and possibly a bit too long)?

 

[Don_R]

Looks like this was a problem before I bought the car. The cable and jacket are new, Possibly replaced by the PO.

As soon as I get some warmer weather I will continue troubleshooting. Such is the problem with no garage to work in.

 

[dklawson]

The swap is not difficult but you may want to switch the speedometer at the same time to keep matching gauges. You will obviously need to disconnect the cable. If you completely remove the cable at the dizzy you will want to cover the male threads there with something like a vinyl tubing cap. You will need to pull a wire from the coil (-) terminal through the firewall to the back of the tach and connect it to the male bullet connector. Obviously you will need switched 12V to power the tach and a good earth connection.