123 ignition timing curves.

[Farmer42]

Hi all. Just fitted my new 123 dizzy and set it up with some curves that Ali posted up a while back. All seems to run ok but just wondered if anyone else had any settings that seem to work for them. I'm running twin SUs on a L26.

Thanks

 

[Geoff-R]

Interested in this. Same setup as mine so will be following.

 

[AliK]

One word of advice: set up two curves and keep one on the app.

I use super unleaded 99% of the time and when I can’t find it, I have a second curve I upload to the dizzy with a couple of degrees taken off to avoid pinking.

 

[Huw]

One word of advice: set up two curves and keep on on the app.

I use super unleaded 99% of the time and when I can’t find it, I have a second curve I upload to the dizzy with a couple of degrees taken off to avoid pinking.

That’s a bloody good idea Ali, why didn’t I think of that!

 

[Farmer42]

Mine just won't run on anything other than super unleaded. Good idea to have more than 1 curve though.

I did read that you can tune it whilst the engine is running. It says that you can add or take up to 10 degrees. Will have to give that a try.

 

[AliK]

Yes the tune function is fun / useful especially when playing with idle or finding optimal timing when engine is loaded on a RR.

 

[atomman]

I put my curves up on this thread and there is lots of good info,

my engine has triple DCOE's , cam and has been worked a bit though

123 ignition for Datsun L6 on my L28

As an aside, it’s not just the radio that gets whacked by RF interference. The old EFI ECU in the s130 was and is quite susceptible to RF interference, this also includes the distributor module. Which is why I continue to run BPRES plugs. Question is tho, is the 123 susceptible to RF...

zclub.net

 

[Farmer42]

Just found this on a US site for 123 ignition:

https://123ignitionusa.com/content/Curve%20Files/Datsun240.JPG

Not sure what fuel system they are running (SU or Weber's)

 

[AliK]

The key thing is your cam and compression (dynamic comp)- on a stock engine with low comp you can probably get away with using lots of advance.

But on RR with my engine we found optimal torque arrived around 29°/30°. So I play it safe running a little less.

I’d be a little careful about using other people’s curves without knowing the engine specifics.

 

[Farmer42]

So, been doing some testing this week with various advance settings and different SU carb needles. Before the changeover, I was running a 280ZX dizzy at 30 degrees with a SU fixed needle on my HS6 carbs on a L26 with stock cam etc.. It ran very rich at idle and at top end (5000+ revs) but pulled really well mid range. The trouble was that my spark plugs became sooted very quickly at idle and it bogged down at top end, feeling like it was overchoking. It was also a pig to start!

I have now changed back to DX needles and installed the 123. Over the week I have managed to seemingly hit a sweet spot on starting, idle and top end without the sooting although the mid range is a bit flat until around 4000 revs. The curve I currently have is:
800 - 15 degrees
1200 - 20
1500 - 30
2000 - 32
3200+ - 35

I don't have the vacuum advance connected so I have not set a MAP curve.

I'm going to try KW needles at the weekend which should give the same idle. These should be leaner than SU at lower and top end and then richer than DX in the mid range to provide a bit smoother throttle acceleration. Will nudge the timing back a little at 3200 revs using the tuning facility on the app whilst its running & see what happens.

 

[Carl Platel]

Good morning, I’m having the same 123 set up issues specifically running rich and like a pig can I ask what you ended up doing and if you managed to solve the problems
Cheers Carl

 

[Farmer42]

Hi. I had SU needles on my carbs that caused most of the problems with rich running. I changed back to DX needles and changed the timing curve to the above then tweaked the mixture on the carbs. Purring like a kitten now and pulling really well all through the range. Although I bought KW needles to go in, it was running so well last weekend, I left it alone.

 

[Carl Platel]

Im learning lots I’m not sure what needles I’ve got but I’ll buy DX and try that thank you I’m now trying to purchase A float -Sync tool as I’m told it vey important to get both floats as close as possible I relay appreciate you taking the time to message back with your experience as I seem to be going through the identical situation
Cheers Carl

 

[Farmer42]

I saw and replied to your other post so I am not going to go into detail about how to set float levels. If there is such a thing as a float sync tool for SUs, then I would suspect that a phone call to Burlen (SU Carb Co.) may uncover one or know where to get one. If not, they can advise the best/easiest way to sync the float levels and also the airflow for each carb. If you are anywhere near Bristol, I don't mind helping you to set them up.