Rebuilt AEC 103A and tachometer

Here's my experience, which doesn't include the Superformance unit: When the "emergency" wiring was used to take the AEC 103A out of the circuit, it dropped the tachometer. Using the negative terminal of the coil doesn't work on these tachometers. For a time I had a Bosch unit and the tachometer didn't work properly. There is a thread on how to add a resister to make the Bosch unit work, but I was never brave enough to change the wiring. I changed to an MSD unit because it has a dedicated tachometer output and works great.

 

I do have the Superformance unit (fitted this year, so a current one) and I had exactly the same experience - when I connected the emergency coil, everything worked fine, but the tacho stopped completely.

 

I purchased the MSD unit after reading a thread by Nuvolari, (don't you just love the talented people in this chat room!). A programmable unit inserted into an original case. It comes at 0 degrees program, so I'm still using the distributor advance, but my tachometer is back and healthy If you the installation, just make sure nothing grounds out - it is an expensive lesson. If the link doesn't work, just search on Dino and MDS.

https://www.ferrarichat.com/forum/threads/msd-ignition-in-a-dinoplex-case-no-points-fully-laptop-programable.533860/#post-144951989

 

These tacho's work with a relatively low signal voltage of between 5 to 12v generated by the Dinoplex unit.
It will not work with the high voltage pulse that comes off a coil - terminal from a normal inductive ignition setup like the superformance one. It can damage the tacho because the voltage spike is somewhere in the range of 200 - 400V (the voltage in the primary side of the coil at the time the points open and the magnetic field collapses).
I would also go for an MSD ignition instead. It has the correct tacho output signal and it seems to be a better ignition system for a Dino engine in terms of power / easy starting. I've also heard of very positive reactions on Winterburns CD-Ignition.

I had to repair one of these tacho's a while ago for a Fiat Dino. There is a very good page on a tacho replacement board for the Dino over here:
http://dinoplex.org/tachoconversion/index.html
There is all the info you'll need to make a new tacho circuit board. There is even a file that you can download to have the circuit board remanufactured.
I made the circuit board and it works perfectly! And you can use it for both a signal from the coil - as well as a signal like from the Dinoplex.
So if you want to keep the current ignition setup you can still decide to change the tacho circuit board.

 

I have been running the SF super 4 (S4) ignition system on my car for several months now and don't have any problems whatsoever.
The tacho is driven from the black wire on the S4 box, not the neg terminal on the coil.
the existing loom should have three wires, yellow(ignition) black (points) and brown (tacho)
The yellow (ignition Switch) wire is for the 12v supply to the S4 box and the Ballast resistor, the brown and blue wires are joined together for the points signal and connected to the black wire from the S4 box.
One thing I would say is that the Distributor needs to be set up perfectly on a specialist machine otherwise you will get problems.
Starting is instant, hot or cold and runs to 7000rpm with no problems at all (dyno tested)
Best
tony