Optimal Ignition curve for 123Ignition with Vac.

[Henrik_K]

Hi guys,

Where - or how - do I find the optimal advancing curve for my 123Ignition?

2.0 Type4 engine.
Cam Web74
Double webers 40 IDF.
Std exhaust.

Thanks,
Henrik

[Alstrup]

Web 74(!) Don´t know that one. What are specs on it?
You don´t.
You take one of the preset curves that you feel works best with your set up. If it is the Vac version you dial in the vacum advance accoirding to how the engine pulls vacum in the respective rpm range.

[StefansBus]

Are we talking 123 Tune (Either USB or Bluetooth)? If so, you first use the dashboard on the app or PC see what kind of vacuum your engine pulls at various RPM and throttle combinations. You then program the curve so that:

1. vacuum advance doesn't come on at idle (There is a cut off function for that in the software)

2. max vaccum advnce is about 10 degrees (I'd start a bit lower) at the maximum vacuum value you measured earlier.

3. Make sure no vacuum advance is present at wide open throttle, only mechanical.

Take some time to observe and think about the pressure readings on the dashboard and how they relate to the advance curve. It's not intuitive!

Unfortunately you cannot program the vacuum advance curve with regards to RPMs, only pressure and degrees of advance (or retard) come into it.

If you don't have one of the two "tune" versions of the 123, then you cannot program your curves and have to pick one of the preset ones. That'll be a challenge with anything other than a stock engine. The people I know that run a non-programmable 123 with a non-stock engine just use the 009 curve and don't use vacuum advance. Not ideal, but it works for them.

Stefan

[Henrik_K]

Typo Web73.

Tak Bo

Its the bluetooth version, I've got.

Thanks.

[StefansBus]

Then I'd start with a fairly simple "mechanical" advance curve of 7.5 to 10 degrees at idle up to 28 degrees at around 3000 or so.

On top of that I'd program some moderate vacuum advance of 7o or 8 degrees at whatever maximum vacuum value your engine pulls. Have the cut off for vac advance well above your idle RPM (such as 1200 RPM) for example.

Set it that way and then watch what it does on your dashboard on your app. Make sure at WOT all you get is your mechanical advance.

Again, take your time to think about how manifold pressure is displayed on the app and how it is entered into the curve. Again, It's not intuitive, I think. But it is logical.

Let us know how you get on and share your results.

Stefan

[Earl Bay]

Hi all. I need some help with the curve. 123 tune+

My engine is in a T2a panel van
92 x 78
Webcam 218/119
AA500 35 x 32 stainless valves, untouched
Rockers: 1.1
Compression 8.7:1
CB Hi Flow manifold
37 Pict-3, 30mm Venturi - jetting: 160 main, 65 idle, 80z air correction
Vintage Speed exhaust
Gutted oil bath cleaner with K&N
Pertronix coil, Taylor leads
123 Tune+
Spark plugs NGK BP6ES
Deepsump, external filter, no additional cooler

I'm currently using this curve from somebody else. So certainly not the best.
It drives fine, no stumble, can accelerate from 30 km/h in any gear without hesitation.

From what I've gathered this centrifugal advance curve shouldn't be too bad
in terms of fairly simple, all in at 28°

But when it comes to the map curve I admit I'm lost. I don't get it.
Epecially the part