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MG MGB Technical - 123 ignition map

Gentlemen,

Can any one please provide me with the chart that applies for this type of ignition in position 3.

The chart showing the advance in dgrees at the various engine speeds.

I am going trying to set up my own ignition according to these settings as I have understood that an engine fitted with a stage 2 cylinder head seems to run without pinking when run with such an ignition.

Thank you in advance.


Frank

Navest

Frank,
It is supposed to be equivalent to the Lucas 41339 distributor. http://www.tdcperformance.ca/tuning_guide.htm does not seem to map the curves for the 123/MG distributor for some reason. Marcel Chichak gives the important data for the 41339 at http://www.starchak.ca/tech/pdfs/lucas.pdf as well as many other useful bits of info, although admittedly primarily oriented around the classic Mini.
David "hope this helps" Lieb
David Lieb

Is this any use?

http://www.mintylamb.co.uk/123ign.html
Geoff E

Which 123, there are several? For the MGA and MGB variant position *number* 3 is the 41339 as has been stated, but counting starts from zero so it is the fourth absolute position, or the third position after the starting position. The third absolute position is the 40897/41155. Curves for these (and all the positions) can be found at http://www.mgb-stuff.org.uk/wn_ignitionframe.htm and click on 'Distributor Curves'. At least one person recommends the Mini variant for standard MGBs (the maker recommends it for certain tuned MGB applications), and the curves are completely different. http://www.tdcperformance.ca/app_mini.htm lists the distributors for each position of this variant, you will have to go to a Mini site for the curves for these. But unless you determine on a rolling road what the ideal curve for your engine is first, then look for a curve that closely matches that, it is all going to be poke and hope, and an expensive one at that.
Paul Hunt 2

Hard to say for sure. There are several models of 123 distributors, including the 123/Mini, the 123/GB4, the 123/GB6, and the 123/MG. The curves are not the same for each of these (other than the GB4 and GB6 apparently sharing the same curves), and this site does not specify which one he is using. The 123/MG unit has curves specifically chosen to emulate the curves that came on a wide variety of the B-Series engines used in the MGB.
David "no easy answers" Lieb
David Lieb

Gentlemen,

Your feedback is much appreciated. The lucas specification that would probably fit is the 40943 for the 25D4 ignition.

The information given to me by a fellow MG owner is a gentleman with B, a stage 2 engine equipped with the famous 123 ignition.

My car is similarly set-up. My ignition is, however, a distributorless solid state afair.

This system allows full adjustment by simply feeding the revised data from my laptop.

Having heard the positive news from the 123 system I am highly interested in the actual diagram.

Meanwhile I have already compared some notes from the 123 Mini set-up. I will have a go at these settings and see what they bring.

Should anyone still come across the proper thing, I would be pleased to learn from you.


Thank you

Frank
Navest

This thread was discussed on 30/03/2008

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