123 ignition and tach question, How do I set up tach to work with 123 ignition Options

[pete-stevers]

I have a 123 ignition on my 2.4 six motor but I am not sure how to set up my tach to work with the ignition.. can I use a 914 tach? What else do I need?

[VaccaRabite]

I have a 123 ignition on my 2.4 six motor but I am not sure how to set up my tach to work with the ignition.. can I use a 914 tach? What else do I need?

Black/Purple stripe wire to coil negative.

Unsure what the wire colors are for the /6. So it may not be the tach wire that is on the /4.

But for a tach you just have a wire to the coil negative. Dizzy does not enter the chat.
Zach

[pete-stevers]

Does the 123 dizzy have enough current to power the 914 tach
or will I need a six tach.. I hope not
the motor is a 2.4 t 1973.5
the tach is a stock 914 4 1974

[VaccaRabite]

Does the 123 dizzy have enough current to power the 914 tach
or will I need a six tach.. I hope not
the motor is a 2.4 t 1973.5
the tach is a stock 914 4 1974

The Dizzy does not power the tach. The coil does.
The tach reads the pulses from the coil divided by the number of engine cylinders and determines the speed of the engine.

Where it matters is that the tach needs to be able to interpret the pulses from the coil to get to the right RPM. I don't know that a /4 tach can do that for a /6 engine. Usually there is a switch on the back of the tach to determine if the engine is 4/6/8 cylinders. On a stock tach, I bet you have to change it for a /6 or go aftermarket. But I could be wrong if there is a switch on the back that I have just never looked for.

But, again, the dizzy is not in the chat for this. Its all the coil.

Zach

[emerygt350]

Like Zach said. Just make sure whatever wire was going to the negative pole on the coil before is still going there now.

[Superhawk996]

I’m not sure there is enough info here.

914 tach for a 4 cylinder definitely won’t play with a six as-is.

914 tach won’t play well with Porsche CDI ignitions often used with six’s and there are also some compatibility issues with 123 and the various CDIs but sort of assuming OP is past this and has a running vehicle?

Don’t forget about using a Tach-Adapt as a potential solution to the 4 cyl to 6 cyl compatibility but really not enough info here to know with certainty what’s going on if I’m not mistaken.

[emerygt350]

It looks like it is a 4 tach hawk. I didn't notice that second post. If so, that isn't going to work. Well, it will work, but it won't read the correct rpm.

The 123 app will tell you rpm but you want a working tach....

[Superhawk996]

It looks like it is a 4 tach hawk.

I don’t even know if we can assume that.

Maybe he has a 914/6 tach? But that tach didn’t work well with CDI and used a little amplifier thing-a-ma-bob “ballast” (basically a signal amplifier) to send a clean signal to the /6 tach. At some point I think 911’s changed the tach to work without the ballast but don’t remember the year off the top of my head, so again back to more unknowns about what ignition and/or tach he’s using.

Apparently I can’t read (IMG:style_emoticons/default/headbang.gif)


A Tach-Adapt would likely solve these compatibility issues to allow use of a 6 cylinder with a /4 tach but without knowing details of what his ignition is (CDI or conventional), what his issue are, and how it’s wired, it’s still a WAG.

(IMG:style_emoticons/default/idea.gif)

[mepstein]

Wonderful little problem solver.

https://ashlocktech.com/tach-adapt-1