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MG Midget and Sprite Technical - 123 electronic ingintion dynamic timing


quick query ...I hope.

Looking to set dynamic timing with 73 RWA fitted with 123 electronic ignition.

Setting the static seems easy enough - fine..

However, I am a little confused as to the procedure for then setting dynamic.

Assuming 32 deg BTDC at 4500 for dynamic setting do I

Set the static and then set the dynamic by simply adjusting the curve set screw on the base of the distributor to suit the dynamic setting above? Positions 8-B if I remember right.....


As above, but then ALSO carry out the traditional strobe method - marking a point on the pulley at 32deg advance of TDC, and rotating the distributor body to ensure it mates with the timing marks at 4500 rpm using the strobe?


Adjust curve set screw to position 0, then carry out the traditional strobe method...

OR none of the above!

Obliged as ever
Mark O


The static setting was an average value for leaded petrol in the 1960's and 1970's.

So today as we have different petrol and probably a more accurate distributor it is just a starting point when setting up the engine.

So set that static as you say and then set the 123 adjuster to the the curve suggested by the 123 literature.

I would think there may be something to be gained from putting a paint mark on the distributor and the base plate to easily get it back to that static setting and rotating the distributor a small amount to see if the performance is improved but not as far as to cause pinking under hard acceleration but you are on your own on that one as it is at your own risk.

By all means check the advance at 4,500 revs to see if it is at 32 engine degrees.
Eddie Cairns

agian mark

the static timing just is a beginning place to safely start the engjne after a rebuild or dissy replacment

you set dynamic to actually drive the car after the engine has been started from the static postion

to do a dynamic time, you will need timing marks, which you mentioned your engine does not have

if it did have timing marks, you hook up the timing light ...aim the flashing light on the crankshaft pully next to the timing spikes...then run the engine at 4500 rpm and adjust the dissy untill the mark on the pully and the spikes line up at the 32 degree mark on the gun will need a more advanced timing gun to do this


use a basic gun and but run.the engine to 1000 rpm and match the marks to the 10 degree spike mark

the advantage of timing 4500 rpm @32 degrees is that detonation happens at a higher rpm and you rarly drive over 4500 you may have some detonation at the lower end but its better there then higher up

adjusting the screw on the dissy its something id have a pro like peter burguss do... its adjusting 1 of several things, like dwell, curve, spring tension, spring length, just a hole host if thing you dont want to be expermenting with

but as I said... make or get some timing mark pointers and get those set up, then you can do a dynamic timing

Prop and the Blackhole Midget

here you go....

because you dont have any timing marks or pointers on your engine

this is what you will need or some variation...I have this one...its a pointer and a timing tape that sticks to the crankshaft pulley

granted in your case you will need to find top dead center 1st, but after that its all down hill forr installing his kit, then you can do a dynamic timing, and intop of the engine instead of under the car
Prop and the Blackhole Midget

Prop your rarely right but in this case as usual your wrong again for a change.

The 123 distributor does not allow change of dwell, spring tension, spring length as it is electronic not mechanical in the majority its functions.
Eddie Cairns


I'm in Aberdeen tomorrow afternoon. I have a timing light you can dial in the advance so yo do not need other marks. If you want a shot

auchenblae at gmaildotcom or I'm in the phonebook and will be in Friday morning.

Eddie Cairns

your correct eddie...

I dont know anything about the 123 / 123 tune...ive never even seen one

please inform us what the small adjusting screw actually adjust on the body of the 123 dissy that mark wishes to twist to adjust ....

you forgot to mention I said that the adjusting screw might also change the curve of the dissy ...did you fail to mention that intentionally on purpose.. or was it just ignorance

btw eddie... marks engine is void of all timing pointers and the crankshaft pully is not orginal and the engine is rebuilt as hi you will need set up timing notches and pointers 1st ....unless you plan on just guessing

thanks for donating your time to help mark

Prop and the Blackhole Midget

As a general comment, the standard damper pulley just happens to be the right size that 1mm around the periphery of the pulley is give or take 1 as well!

To be spot on add 1mm to marks over 10, so 32 BTDC is 33mm from the TDC mark. For that short distance you could ever use a pair of calipers to measure it, as the difference between the chord and the arc is minimal for 32 (0.4mm).

Richard Wale


Many thanks for your kind offer - much appreciated. I will however set the static as per the instructions and set the curve - think I will try No7 setting and take it from there, possibly with a mind to rotate the distributer CCW slightly if it starts pinking again.

I was just a bit confused as to how to set dynamic with a 123. Basically it now seems that is set by selection of a suitable curve - and that is all.

Distributor will be marked up as you suggest, and follwing that theme, think I will add a new pair of timing marks on the pulley and timing chain cover where I can see them form the top. I do have the originals - contrary to what our redneck friend states.

I do enjoy such comments from Richard..terrific stuff!
Mark O


you said the reason you can not use a timing gun was because you have NO timing pointers, and marks or notches

now you say you do ???

im completely lost

setting dynamic timing has nothing to do with the guessing that should be set before the dissy is even installed.

Prop and the Blackhole Midget


There is a bit more to it than that. What hasn't been mentioned (that I have seen above after a quick scan after a quiet glass or to after dinner!) is any mention of intermediate advance. That is really important for lower-mid range performance. Max advance is really important for max power and good engine life. Idle advance is the least important condition. Get the other two right has a big effect on performance and engine life, whereas the engine is much more tolerant of +/- at idle. (For evidence of the latter, look no further than the range of idle advance setting on the MGB engine, which varied from about 10 deg to around 25 deg - vacuum connected which is how the engine runs)

So to expand a little on the methods advocated above:

1. Select the curve that 123 recommend for your engine.
Set the static advance as per book.
2. Check the maximum advance
3. Rotate the distributor body to give the correct max advance.
4. Road test to check intermediate advance at around 2000 RPM +/- 500 RPM. There shouldn't be any pinking. 5. If there is pinking, select a curve with less intermediate advance.
(If you want to persevere for optimum results, if there is no pinking select a curve with a little more intermediate advance)
6. Repeat steps 2-5 until you have both correct max advance and an intermediate advance which only just avoids pinking (alternatively a VERY slight trace of it is acceptable)
7. Let the engine idle. So long as it's between 5 an 20 deg andf the engine shows no sign of pinking on the transition from idle to mid-range, it will be OK. If there is pinking, you will need to select a curve which retains the max and intermediate advance, but has less idle advance.
8. Once you are happy with where you have got to, note the idle advance (and RPM) and record it for future use - that's what you reset the distributor to whenever you need to set ignition timing in the future.

It is also useful to turn the engine off and then note the static advance that you final combination gives rise to so that you can set statically if you need to in future.
Paul Walbran


The 123 distributor has a number of different electronic curves programmed into the solid state device that are there to suit a number of engines that the unit is speced for. These are obviously average curves rather than specific curves for that particular engine.

The screw that mark is talking about selects which stored device curve that the unit will use.

The latest version of the 123 distributors is connectable to a computer and allows you to change each part of the curve to allow it to be set up on a dyno to match that particular engine.

Eddie Cairns

wow... im really sorry, I was under the impression the curve was set, soooo, now its not, sorta like there was no timing marks, pointers.or notches and now there is...

wow... thats a long way from where this thread started under part 1 titled .. "pinking" before it came to this thread

orginally we were talking about valve adjusent then static timing adjustment then dynamic timing and NOW we have come all the way to setting the curve of the dissy....which appeartly has not been set orginally or has it, ive lost track

to back up what paul was talking about here js a great utube video..that talks.about setting up a curve with (idel, intermediate, and total timing) its with a V8 and by MSD... but the concept is the same

Mark O... I wish you the best, and happust of luck but I can no longer preticiapate in this endeavor of insanity

my best advice ... know what jt is you want and take it to a pro, that can sort it out...not a modernday shop... someone with experiance on classic brits... id highly recommend peter burguss...I doulbt he is cheap, but the man knows his stuff and can give you an.awsome running car


Prop and the Blackhole Midget

Prop - I said I had no dynamic reference points - that is degrees advance and the associated RPM - not no timing marks. I do now have some guidance for dyamnic reference points.

Paul - Having a modified engine, there are no true dynamic advance recommendations, but I have the curves for the 123 pre-programmed unit so installed.

Guess you could indeed do as you say - indeed I think that is what Peter B. recommends in his blurb, but I guess you could also rotate the distributor body CCW to remove any pinking.

Thinking of starting at curve 7.... 22 deg at 2000 and 30 at 4500.

Mark O

hey eddie... yepp a very cool set up... its called the "123 tune" MSD came out with its version about a year ago and supposedly mallory has got one its version of "TUNE" comming out soon if not already...but im thinking its more of a modified unilite model

me ive still got a crush on the Y-27 series duel point mallory from the 70s just specks to me

if I did go 123 tune, then id probably go efi also...they just kind of work togather... maybe even throw in a turbo for good measure....somehow that just seems like cheating...hahaha


Prop and the Blackhole Midget

hey eddie

hear is proof im a real redneck hill billy... ultimately im going to set up the worlds 1st mg midget duel ignition system

ill have the mallory for primary driving then ill have a ford edis crank shaft pulley set ... but retarded about 4 degrees with a toggle switch hooked to the 1 st gear of the tranny shifter

I got most of the parts to do it...

why, im sure your asking.... well anti traction from the starting line of coarse....hahaha

truthfully... pure vanity simple as that, just the challange to make will definatly be a fun and educational experiance

well that and art.. the car is my canvas and vanity is my favorite sin

I got the idea when seeing a duel ignition on some of the good ol boys oval dirt track nascrap its not purely my idea to begin with


Prop and the Blackhole Midget

That's exactly where I would start.
In the absence of a rolling road session, set to 30 deg at 4500.
Then check advance at 2000 to make sure it is 22 deg as spec and the wrong curve hasn't been accidentally selected.
Next do as you say, rotate distributor a little at a time until on the verge of pinking.
Read the 2000 RPM advance at this setting.
Then go back to the curve selection and get one with this 2000 RPM advance and 30 deg at 4500. That's the one you want. or rather, your engine wants.

The problem with just simply rotating the distributor and then leaving it at that is that the max advance will be sub-optimal. At best it will lose power, at worst it will damage the engine. Combustion irregularity is much more difficult to hear at 4500 RPM, so by ear you can't tell if it's safe or over-advanced.

The 30@4500 figure is one which is going to be safe and reasonably close, hence OK to use in the absence of RR session, so is the one to aim for as well as optimising the intermediate (2000RPM) advance. Anything less than getting both figure right doesn't do the engine justice.
Paul Walbran

Many thanks Paul - much obliged. Within the curve settings of 30 at 4500 max advance there are also 4 options for the mid range....16 - 22 deg at 2000
Mark O

Almost everything here youve stated here is gibberish or just plain rubbish! Congradulations!
These are some of the most useless postings Ive seen you do in a long time! Well at least since that Brainless utube vid!

Oh ya mallorys suck!

Ha ha ha....
Steven Devine

Please steven...

Use the really dirty rusty knief, not the new crisp shinny sharp 4 inch blade.

stick it in deeper all the way in before you twist, then pull it out....and if its okay maybe a little bit lower in the back would really be great for me...thanks

Friend ?

Prop and the Blackhole Midget

Done! Now what! Ha ha ha
Steven Devine

"Why don't you knock it off with them negative waves. Why don't you dig how beautiful it is out here?
Why don't you say something righteous and hopeful for a change?"
Steven Devine

Interrupting the battle of Gettysburg for a moment here, would update all with events over the weeked which may prove useful for fellow members with a similar 123 set up. After switching the curve to position 6, things improved greatly, but still a wee bit of pinking uphill. Nudging the distributor body round a very little CCW - and I do mean a little - removed it and also improved the mid-range a wee bit further. In addition, I opened up all valves a smidge to 16 thou - as per cam shaft installers recommendations - Kent fast road cam....

I now have a much more responsive car, with a much improved mid-range pulling nicely in 5th even up a slight grade. A result I believe....and jolly nice it was too zipping along in the spring sunshine by the river and along the glens.
Mark O

Yay! very rewarding :-)
Paul Walbran

Gettysburg? Ive got nothing against the south.
Some of my favorite music and people come from there!

You mean me and Prop?

Props not totally useless, he can always be used as a bad example! Ha ha ha... I think he must have had a bad day. He doesnt usually threaten me with knives all the time. I think he is upset and still trying to find the right words to express himself...Right Prop!

Glad you got your distributor sorted out Mark! Do they make an application for the B series engine?
Steven Devine

well done on finding a better 123 setting for your car, you might want to check your carbs again to see if there's a tweak required now, then leave all well alone until the next service or rolling road check/set-up and just enjoy driving the car

yes they do
Nigel Atkins


You must forgive my humour - and do please note the correct spelling of the word "humour"....

I believe 123 is available for the B. Peter Burgess' web page tells all. A jolly good read....

Pricey bit of kit though. Cheaper electronic and optical ignition kits are available - which following the well known principle of rotate the distributor body until correct advance timing is found by trial and error, will I am sure, work just as well as a substitute for points.
Mark O

Thanks Nigel!

Thanks Mark, nothing to forgive, I would have used it,If I could apply it! The humour that is!
Ill check out the website!
Steven Devine

congrats mark

well done... its great when a project comes togather

enjoy the spring and summer...youve earned it

Prop and the Blackhole Midget

He could have done it with out you prop! Oh and he did! Ha ha ha ha ha ha ha ha!
Steven Devine

No need to get yourknife out! Just joking!

Ha ha ha ha ha ha
Steven Devine

This thread was discussed between 18/04/2013 and 22/04/2013

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