After spending five years re-restoring my 71 240 due to flooding of two feet of sea water, it is back on the road. One minor issue I can not rectify is that the tach is pegged over to 8K at idle. This is an occassional issue. I checked the wires to the coil and ballast resistor and they seem to be ok, though i cleaned the contacts and applied dialectic grease with no change. Any ideas?

Thanks

Jim

71 240 Z

I am curious with no answers, do you have points or something like a pertronix ignition?

Mine did the same thing. The problem is the tach itself. Replacing the tach is the simple fix. I was able to fix mine by replacing the 2 transistors on the PC board in the tach. You might be able to have it serviced at a shop. The internals are essentially the same as the Smith meters used in many of the English cars from the 60s.

My 260Z tach had the same issue (although it's a bit different than a 240Z tach). Replacement made it all better.