Modern Tach won't work with points?

[tubman]

I think switching to a 12 volt coil (and changing the wiring accordingly) will work. There are 2 electrical feeds needed by the tach. The tach logic itself is designed to use 12 volts. But the signal coming from the distributor (green wire) has to be 12 volts as well. I have been there and done that. We at first thought that the voltage of the ignition signal "just had to be there", but soon found out that it also has to be the proper voltage and polarity.

[markdtn]

Originally Posted by tubman

I think switching to a 12 volt coil (and changing the wiring accordingly) will work. There are 2 electrical feeds needed by the tach. The tach logic itself is designed to use 12 volts. But the signal coming from the distributor (green wire) has to be 12 volts as well. I have been there and done that. We at first thought that the voltage of the ignition signal "just had to be there", but soon found out that it also has to be the proper voltage and polarity.

After reading your post I believe you are probably on the right track. All 3 tachs I have had acted the same way. I-and probably many of you-think of the mid '70s as not that long ago but it was 50 years. And my 1950 8BA was 75 years ago now. Lots of water has flowed under bridges since then. So maybe it's not so crazy that modern tachs won't work with pre-electronic ignition, ballasted 6V coils of the '70s and prior.

I am going to buy a 12V coil even if it messes up my beautiful wiring job.

So, best recommendation on a 12V coil still a Bosch blue 00012?