Fiat Dino Forum (FDF)

Greetings. I know tacho issues have been discussed in the past, but I seem to be having a problem I cannot solve - Please help!

My car is a 1967 coupe with an early serial number - 835. It was never fitted with a Marelli electronic unit.

The previous owner fitted an aftermarket electronic ignition many years ago. The car runs GREAT. I am using the recommended spark plugs, and all is well.

Except that the tachometer does not work properly. It was not working when I bought the car 3 years ago, so I sent it to Seattle Speedometer to have it redone.

It did not work properly when it came back, so I sent it back again. It still doesn't work correctly. The tach looks nice, but it does not work correctly.

The problem is that it seems to read high, and erratically. It does not move with the engine speed - It seems to be slow. It also gets stuck at 3,000 or so, and then will start to move again after a while - reading high and being slow.

I have attached a picture of my setup which is as follows:

Marelli coil BZR202A with a small red Magneti Morelli block on top which is attached to the coil with a bracket.

The coil negative has a red wire that goes to the Magneti block on the coil.

The + on the coil has a red to a condenser, a yellow going into the car wiring harness, and a white to the electronic ignition module.

The Marelli block on the coil has a D terminal that has: brown to tachometer (I assume)
green to electronic ignition module
red to coil negative

The coil also has 3 small wires (red, black, brown) that go to the distributor.

Any help will be appreciated!

Thank you!
Mike

Your coil with resistor (red block) is suitable for use without a Dinoplex, i.e. Emergenza setup. I can't say how it works with your ignition system that I don't know. I'd suggest to install a Dinoplex or a replacement mentioned here: http://www.dinoplex.org

Looks like you have some sort of transistor ignition system build into your car.

It is at least a bit messy and slightly confusing with all these different colors of wiring attached to it. But maybe you can check what is inside your distributor because if there are 3 wires going to your distributor you most likely don't have your points system in there anymore and it has been replaced with something else.
Please try to figure out if the tacho wire is mounted to the actual coil - terminal, or in other words to the wire that actually switches to coil to ground, ór that it is attached to some specific pin or wire from the 'transistor box' which could be a low voltage signal that is generated by the 'transistor box' which would be used as a switching current for the points / hall sensor etc.

The Dino tacho's use a low voltage signal for the tacho instead of the usual tacho's that take the much higher voltage spike from the coil - terminal. My car is a much earlier serial number and that tacho would not work correctly with the usual coil - setup.

Here is your website with all the information to make a tacho circuit board for your dino that would work with both signals.
http://dinoplex.org/tachoconversion/index.html

I follow all the instructions and made one and it works perfectly

Hi, could this be the solution:
http://www.dinoparts.eu/DE/fiat-coupe-s ... ssung.html