pre-programmed curves on 123 ignition - help please?

[malcolm]

Hi all, there's been a lot of posts on the 123 tune dizzies recently, with typical curves etc.
I have a standard (probably old model) 123. You can't choose advance curves - you get what it is. I have now checked what timing I'm getting, with vacuum disconnected.
My static timing is right, at 10 btdc.
My mechanical advance, inc. static, is right giving me 29 btdc at 3600 rpm.

However, the interim curve seems a long way behind.
At 2500 rpm I'm at 21 rather than 25
At 1600 rpm I'm at 12 rather than 23!!

Presumably this will adversely affect my performance, including my fuel consumption? I ask, because whereas I used to get 22mpg on my old dizzie, I'm now getting about 17!

I'm thinking of changing it for the modern 123 ignition, NOT the tune version, which has 16 pre-programmed curves. What would be really helpful would be if someone here knows what the interim curves are on this newer model, and which curve they chose. Basically, if the interim advance is not much different to what I have, there's no point in me changing it.
Thanks in advance!

[mgcjag]

Hi Malcom...youve already confused me There are 3 123 versions.....the 123 which has 16 pre programed curves...the 123tune which is programable & the 123 tune+ also programable but with more features and an app to go with it....Steve

[malcolm]

Hi Steve, I currently have an OLD 123 with no curve choice fitted. It provides the advance at various rpm as per my post. I think that advance is too little at lower revs, so am thinking of changing to the more modern 123 with 16 pre-programmed curves you can choose from. (NOT the tune or tune+)
My question is which curve people with this distributor people have chosen, and what the curve looks like at various rpm.

[Tom W]

Actually, there’s 4 versions.

The 123 6cyl. 16 pre-programmed curves for typical British 6 cyl cars
The 123 Jag. 16 pre-programmes curves specifically for Jaguars, though none seem to quite match the E-type factory curves.

Then 2 Tune versions. With or without Bluetooth. Though apart from the interface for programming them, they both do the same thing.

Doesn’t yours have a plug underneath with a little switch behind to change the curve? On early ones, it was on the bottom and the distributor had to be removed to change curves. Later, it moved to the side so was accessible on the car.

[malcolm]

Thanks Tom. The one I am looking at is the one for Jaguars as opposed to the "Typical British"

Mine has no switch as far as I know, and as far as the people who fitted it know! They told me there are no curve choices. I've looked on the sides, and all I can see are the numbers "123" and some colour guidelines for wires. Presumably this must be a first edition!

[Tom W]

I’ve not heard of one without a choice of curves before, though that doesn’t mean it doesn’t exist.

Have you downloaded the instructions for the Jag version, and checked there’s a curve in there that does what you want?

[Tom W]

I should also add to my above list, there are versions with and without vacuum advance, and positive and negative earth variants.

[malcolm]

Hi Tom and all! UPDATE!
I have now crawled around the unit, and found a window positioned so it faces a tricky-to-reach position. I didn't fit this; a mechanic did.
I managed to get an Iphone between the window and the block, and lo and behold, I'm sure it DOES have the 16 curves!
I'll post a picture in a minute, and hopefully get more advice!

[malcolm]

So here we have it.




You can see a white arrow pointing at the number zero, so that is presumably the curve selected?

To choose a different curve, do I just twist the arrow? (I don't have instructions,or anything!) And if so, which curve do I choose? Does anyone know which of the numbers or letters are closest to the 4.2 standard curve? Incidentally, this I think is a dutch supplied model. It says 123ignition.nl
It also on the other side says Jaguar, but can't read the rest.
I really need to know
1) How to switch curves
2) Which curve gives me the early advance I need.

[rswaffie]

Hi
The 123’s are produced in the Netherlands I believe. I had to send mine back to Holland when I needed a warranty repair.

The link to the manual is https://www.123ignition.de/ignition/Cus ... TCH6_1.pdf

The (limited) info relating to each setting on the dial is at the end. Just look for the 123 Jag section.

I’m guessing it will be either 0 or 1 unless you have some sort of race mods.

[malcolm]

Thanks Richard, I did find that manual but it only shows the max advance and revs for that advance, doesn't show the interim values. As I mentioned, I believe I'm on curve 0 (Static advance fine, max advance fine as tested by strobe) but 1600 rpm only gives me 12 btdc when it should be 23! So well behind the game.
I could I suppose work my way through all the curves and test with strobe, but the little arrow, if that is how you change it, is a sod to get to so I'm trying to find out in advance what might be the best choice of curves. If I had graphs of all the curves, showing values at different revs, it would be great, but I contacted holland and they said they don't have them!

[Tom W]

The curves for the Jag version are in here. https://www.123ignitionshop.com/manuals/123JAG6.pdf

They all start at 12 degrees, but that’s only 12 degrees if you set the distributor to 10 degrees static timing point as per the instructions. Setting the distributor to a different static point will alter all the points on the curve by an amount corresponding to the difference.

The curves are grouped into 5 groups, by total advance. The difference between the curves within each group is down to how quickly the advance reaches the maximum.

[malcolm]

Thanks Tom, that helps because it shows one interim value at 2000rpm. However, it shows max. advance ranging from 34 to 42! Max mechanical advance on the 4.2 should be 29. However, I think the table you posted includes 10 degrees vacuum advance; is that right?
The table is the same exactly as the one Richard linked to from Holland, except all maximum advance figs are 10 degrees higher! That's not because I'm forgetting the 10 degrees of static timing; pretty sure the max mechanical advance figures used by Christopher Storey and others on another 123 thread were 29 degrees including 10 degrees of static advance? viewtopic.php?f=3&t=15966#p130925

So I think I can take 10 off to equate to Christopher's figures on the above linked thread?
This the original table, with max advance 10 more than Toms everywhere http://redirect.viglink.com/?format=go& ... TCH6_1.pdf
But although that minus 10 works on the max advance number, it doesn't on the interim numbers! Otherwise we get 2 degrees at 1200 revs and about 10 degrees at 2000revs!!

[Tom W]

The way I interpret the 123 instructions is as follows. The figures in the instructions are crankshaft degrees without vacuum applied, and with the static point (LED) set to 10degrees. There’s a note that it says they’re with the vacuum disconnected.

The vacuum applies up to an additional 10 degrees on top of this.

As the LED is only a setting aid, effectively the figures are what you get with the idle timing set to 12 degrees.

If you want 29 degrees maximum mechanical advance, with curve 0 for example, the idle timing would need to be 7 degrees.

The factory curves for the series 2 are in the workshop manual. There’s a tolerance on the acceptable distributor curve. At the upper end of tolerance with a 10 degrees idle setting, 31 degrees maximum at the crankshaft without vacuum would be acceptable.

[malcolm]

Hmm. Seems odd that the specific distributor for the e type requires a static advance of only 7 for the mildest curve to be within limits. And why are all the max. advance numbers exactly 10 degrees more than this table https://www.123ignition.de/ignition/Cus ... TCH6_1.pdf which assumes static advance set as per the instructions at 10btdc? Still confused.
I'm actually set on curve zero it seems, and definitely have 10 degrees of static, but my max at 3600 rpm is 29 inc. static. Which is about right! It's just the interims I'm not happy with.
I do appreciate the help though, and I'm slowly getting there I think. Bear with me!

[Tom W]

The numbers are all 10 degrees more, because the two tables are counting from a different point. The one I linked to assumes the distributor is set at 10 degrees static relative to the LED, which is actually 12 degrees at idle (2 degrees beyond the “static” point)

The table you linked to is showing crankshaft degrees beyond what the static point is set to. So if your static point were, for example 10 degrees, the total advance for the two tables would match. For some reason it doesn’t mention the “missing” 2 degrees in the table you linked to.

The whole thing is very confusing, particularly as the instructions don’t give the complete picture, or present the information in the same way for each model.

Do you have the Jag version, or the GB version? The GB version looks like it has an additional 17 degrees on top of the static setting, which is much closer to what you’re seeing.

Maybe the 123 doesn’t actually do exactly what the instructions say?

[malcolm]

The version I have is the jaguar version. Seen it stamped on the dizzie.
So from what you're saying, I'm back to thinking why does the specific Jaguar dizzie have curves so much higher than they should be for any standard 4.2? Having to reduce static timing to 5 degrees to get the basic curve (zero) down to a total of 29 max seems bizarre. Any curve above 3 on this basis is unusable, and no point being there.
Yet on my strobe, with 10 degrees static, my maximum advance is actually only 29!
I might put curve 5 in and see what happens!

[Tom W]

I heard the curves in the Jag 123 were based on those in Des Hammill’s book, which does include advance settings that go a lot higher. Not much use for those that want something standard.

I don’t have an advance timing light, so I can’t check what mine does beyond idle as the timing marks on the damper don’t high enough.

Are you sure your tacho is correct? I found mine over read with the 123.

[malcolm]

Yes, tachometer still fine against gps speed

[Tom W]

Does your advance stop advancing at 3600 rpm then, with the vacuum disconnected?