123 Dizzy

[boyzie]

Hi All
Probably going over old ground but took the plunge and bought a 123 dizzy for my 2110.

Any feedback from users of the 123 dizzy in terms of curve to run and initial setup?

Cheers

 

[sparkywig]

All depends on your engine. Cam spec and carbs make a massive difference.
Take it to a rolling road and they can set the best ignition curve when they tune your carbs.

 

[StefansBus]

Do you have the 123 Tune (USB or Bluetooth) version?

Cam and Carb do make a difference but more so for the vacuum advance function than for the "mechanical" advance.

You can typically set ignition to 8 to 10 degrees before dead center at idle, 20 degree at 2000 RMP and about 30 degrees at 3000 RPM. It'll probably run quite ok and safe like that. Some vacuum advance will help in the low load, low to mid RPM range. Make sure vacuum advance only comes in way above idle and not more than 8-10 degrees total additional advance. 6 might be enough. With vacuum advance you can get typically get away with leaner ill jetting getting you better fuel economy.

As for the absolute vacuum values at which vac. advance comes in and maxes out, you do have to test that on the road or on a rolling road. You need to know what the max vacuum is that your engine pulls. This will be at a low load (almost closed throttle), but high RPM. Then you set your max vacuum advance (I'd start wit h6 degrees) at that value.

This worked really well for my 1776 with modified 34 PICT and a CB 2239 cam but should get you in the ball park even with a different setup.

 

[boyzie]

110 cam twin dell DRLA 40's , planning a tune and RR session

All depends on your engine. Cam spec and carbs make a massive difference.
Take it to a rolling road and they can set the best ignition curve when they tune your carbs.

 

[rlepecha]

Evening,

A couple of years ago I pulled a lot of information off the web on the advance curves of original bosch distrubutors, and new ones; along with ignition maps developed by numerous people on The Samba for the megajolt/megasquirt/CB Black box.
Additionally using some calculations & data from the web I developed a theoretically ideal advance curve and plotted this against the manufactured equipment.
I started this whilst trying to map an Aldon Amethyst ignition system, which turned out to be problematic in my bus and I replaced it with a crank fired NODIZ set up.
You may well be able to use this information to develop the curve on the 123 ignition, although I think you are limited to just inputting the vac and mechanical advance curves. To reach the ideal you really require a multi-cell igntion table (10> x 10>) with MAP or TPS & RPM which I acheived through going crank fired with NODIZ.

Ultimately, if you end up a couple of degrees short of the of the maximum performance curve (read - ragged edge of detonation) by using a pre-existing dizzy curve, or the one developed by myself in the attached (See current ignition map column) you will not see a massive reduction in power. If anything, having a bit of tolerance between the detonation limt and your curve is advantageous in case you end up with a tank of poor quality fuel.

https://drive.google.com/file/d/1sSSygKef5zyHF3mtdM4-uvf6hwPWHXDF/view?usp=sharing

Feel free to drop me a PM if you want some further information on the spreadsheet, but hopefully it is reasonably self explanatory.

Also, if anyone has details of advance curves developed for your engines on a rolling road that they would like to share; please send them across and I will add them to this sheet and we can see how different they are from the original dizzy curves.

EDIT:
Heres the original thread I created discussing this, which has much more detail than the above. The spreadsheet linked in it is an older one though.
https://forum.earlybay.com/viewtopic.php?f=4&t=72412&p=594696#p594696

 

[StefansBus]

Evening,

A couple of years ago I pulled a lot of information off the web on the advance curves of original bosch distrubutors, and new ones; along with ignition maps developed by numerous people on The Samba for the megajolt/megasquirt/CB Black box.
Additionally using some calculations & data from the web I developed a theoretically ideal advance curve and plotted this against the manufactured equipment.
I started this whilst trying to map an Aldon Amethyst ignition system, which turned out to be problematic in my bus and I replaced it with a crank fired NODIZ set up.
You may well be able to use this information to develop the curve on the 123 ignition, although I think you are limited to just inputting the vac and mechanical advance curves. To reach the ideal you really require a multi-cell igntion table (10> x 10>) with MAP or TPS & RPM which I acheived through going crank fired with NODIZ.

Ultimately, if you end up a couple of degrees short of the of the maximum performance curve (read - ragged edge of detonation) by using a pre-existing dizzy curve, or the one developed by myself in the attached (See current ignition map column) you will not see a massive reduction in power. If anything, having a bit of tolerance between the detonation limt and your curve is advantageous in case you end up with a tank of poor quality fuel.

https://drive.google.com/file/d/1sSSygKef5zyHF3mtdM4-uvf6hwPWHXDF/view?usp=sharing

Feel free to drop me a PM if you want some further information on the spreadsheet, but hopefully it is reasonably self explanatory.

Also, if anyone has details of advance curves developed for your engines on a rolling road that they would like to share; please send them across and I will add them to this sheet and we can see how different they are from the original dizzy curves.

EDIT:
Heres the original thread I created discussing this, which has much more detail than the above. The spreadsheet linked in it is an older one though.
https://forum.earlybay.com/viewtopic.php?f=4&t=72412&p=594696#p594696

Very interesting. Just had a quick look at the thread you linked to where you go into more detail. I find it interesting that at first glance it appears that the map is very close to the ballpark figures I mentioned in my above post. I'm quite convinced these get one pretty close to optimum in most of our engines as a couple of degrees change in either direction won't make a massive difference.

I was wondering though: Why set the dizzy to 7.5 static? It's also what the instructions of my 123 told me to do but I decided against it. To me this only makes sense if using pre-created curves that are baed on that 7.5 static initial setting.

For me, starting from scratch, it was much easier and logical to set the dizzy to 0 degrees static and then set up all timings relative to that. So my table would say 10 degrees advance at idle and that would be 10 degrees BTDC. Same for 30@3000. To me that is much less confusing. I results in absolute numbers in the table and not numbers that are relative to the static setting of the dizzy. Or in other words: Relative and absolute are the same if static setting is zero.

With regards to the 123 tune. It works great for my application but it has two potential drawbacks:

1. The advance additional vac advance is only(!) based on vacuum, regardless of RPM, wiht the exception of the idle cut of which can be defined. That's the RPB below which no vac advance will be added. But above that number, for any given vacuum signal the additional vac advance will be the same regardless of whether the engine is at 2000 or 5000 RPM. People who like total control over their ignition map might not like this. For me, in practice it has not been an issue at all. My engine runs absolutely flawlessly with zero hesitation or flat spots.

2. The vacuum advance appears to be referenced to absolute, not relative pressure. So if you are at a high elevation wth lower atmospheric pressure, there will be additional vacuum advance, which is not desirable. This would only become relevant when driving through large elevation changes such as from the low lands across alpine mountain passes for example. This info is from a German bus forum. I have not been able to verify if it is 100% correct.
In any event, and to stay on the safe side, I have limited max vac advance to 6 degrees, which is all my engine seems to need to run perfectly, and I always use 98 octane or better for increased detonation margin.

Stefan

 

[rlepecha]

Evening,

A couple of years ago I pulled a lot of information off the web on the advance curves of original bosch distrubutors, and new ones; along with ignition maps developed by numerous people on The Samba for the megajolt/megasquirt/CB Black box.
Additionally using some calculations & data from the web I developed a theoretically ideal advance curve and plotted this against the manufactured equipment.
I started this whilst trying to map an Aldon Amethyst ignition system, which turned out to be problematic in my bus and I replaced it with a crank fired NODIZ set up.
You may well be able to use this information to develop the curve on the 123 ignition, although I think you are limited to just inputting the vac and mechanical advance curves. To reach the ideal you really require a multi-cell igntion table (10> x 10>) with MAP or TPS & RPM which I acheived through going crank fired with NODIZ.

Ultimately, if you end up a couple of degrees short of the of the maximum performance curve (read - ragged edge of detonation) by using a pre-existing dizzy curve, or the one developed by myself in the attached (See current ignition map column) you will not see a massive reduction in power. If anything, having a bit of tolerance between the detonation limt and your curve is advantageous in case you end up with a tank of poor quality fuel.

https://drive.google.com/file/d/1sSSygKef5zyHF3mtdM4-uvf6hwPWHXDF/view?usp=sharing

Feel free to drop me a PM if you want some further information on the spreadsheet, but hopefully it is reasonably self explanatory.

Also, if anyone has details of advance curves developed for your engines on a rolling road that they would like to share; please send them across and I will add them to this sheet and we can see how different they are from the original dizzy curves.

EDIT:
Heres the original thread I created discussing this, which has much more detail than the above. The spreadsheet linked in it is an older one though.
https://forum.earlybay.com/viewtopic.php?f=4&t=72412&p=594696#p594696

Very interesting. Just had a quick look at the thread you linked to where you go into more detail. I find it interesting that at first glance it appears that the map is very close to the ballpark figures I mentioned in my above post. I'm quite convinced these get one pretty close to optimum in most of our engines as a couple of degrees change in either direction won't make a massive difference.

I was wondering though: Why set the dizzy to 7.5 static? It's also what the instructions of my 123 told me to do but I decided against it. To me this only makes sense if using pre-created curves that are baed on that 7.5 static initial setting.

For me, starting from scratch, it was much easier and logical to set the dizzy to 0 degrees static and then set up all timings relative to that. So my table would say 10 degrees advance at idle and that would be 10 degrees BTDC. Same for 30@3000. To me that is much less confusing. I results in absolute numbers in the table and not numbers that are relative to the static setting of the dizzy. Or in other words: Relative and absolute are the same if static setting is zero.

With regards to the 123 tune. It works great for my application but it has two potential drawbacks:

1. The advance additional vac advance is only(!) based on vacuum, regardless of RPM, wiht the exception of the idle cut of which can be defined. That's the RPB below which no vac advance will be added. But above that number, for any given vacuum signal the additional vac advance will be the same regardless of whether the engine is at 2000 or 5000 RPM. People who like total control over their ignition map might not like this. For me, in practice it has not been an issue at all. My engine runs absolutely flawlessly with zero hesitation or flat spots.

2. The vacuum advance appears to be referenced to absolute, not relative pressure. So if you are at a high elevation wth lower atmospheric pressure, there will be additional vacuum advance, which is not desirable. This would only become relevant when driving through large elevation changes such as from the low lands across alpine mountain passes for example. This info is from a German bus forum. I have not been able to verify if it is 100% correct.
In any event, and to stay on the safe side, I have limited max vac advance to 6 degrees, which is all my engine seems to need to run perfectly, and I always use 98 octane or better for increased detonation margin.

Stefan

Hi Stefan,

The reason I set the Aldon amethyst to 7.5 degrees static is because the distributor rotors will typically allow for 40-45 degrees advance before the tip moves too far from the rotor pins. If you have 10 degrees of vacuum and 30-31 degrees of mechanical you get very close to this limit and may see spurious misfires depending on the exact rotor in use.
I suspect this is the same reason the instructions for the 123 dizzy tell you to do the same.

Given your map is only pulling 6 degrees of vac advance you probably won't see this issue, but I did when using the amethyst.

Thanks
Ryan

Sent from my One Pro using Tapatalk

 

[ozziedog]

Ozziedog,,,,Well yes. :mrgreen:

 

[gas1man]

:lol: :lol: :lol: :lol: :lol: Ozzie , you are special you are.

J & P