Before you go about repairing the tach, you might want to take a look into what made it fail. It definately sounds strange that your new tach would be off by a factor of two, I'd think that something external to the tach is going on. I put a tach from a '76 in my '79 CVCC, and everything worked fine, so I don't think they changed over the years.

By Username (Username) (68.116.93.157) on Tuesday, July 12, 2005 - 11:44 pm:

I think that the earlier cars had the fuel pump shutoff on the oil pressure circuit and the later ones were off of the tach, not that this would in and of itself cause the problem, just that there are some differences. The last bobbin style guage that I had someone else do was through Speed-o-tach in Walnut Creek CA. might give them a try.

By Kurt (205.250.99.236) on Tuesday, July 12, 2005 - 10:28 pm:

Ya I don't think the year of the car changed anything tach wise. I have seen some guys use the first gen Accord tachs perhaps the guts are the same?

The first gen tachs go to the negative side of the coil. Shot in the dark here but perhaps try a different coil?

By Emfag108@aol.com (Ed) (152.163.100.199) on Tuesday, July 12, 2005 - 07:28 pm:

The tachometer on my '78 CVCC recently stopped working. I checked all wiring external to the unit itself and found no problems. Thus, the failure is internal to the tach. It is easily disassembled and basically has a circuit board with discrete components and a standard meter movement that is typical 1970's technology. Can anyone suggest either a shop or an individual who repairs these tachs? On the other hand, it would be ideal if I could simply obtain a circuit diagram for it. I can do basic electric troubleshooting and repairs myself. Does anyone have any suggestions on where such info could be obtained? What occurred when I replaced the tach in that car with one from a '77 CVCC parts car is quite interesting in my view. That replacement tach does work but indicates approximately twice actual rpm. I checked it and found the paint applied over the calibration pot on that tach was undisturbed. In other words, the previous owner had not be doing some calibration work of his own. Any suggestions on this aspect would be much appreciated as well. It seems odd that it would reliably operate but be off by a factor of two given that the 77's and 78's are so similar.

Ed Faggart
Lincolnton, NC