Misfire and 123 distributor

[rob walker]

As many of you will know I (or the pagoda) has been plagued with a misfire at around 3000 rpm for as long as I can remember. This was worsened by the fitment of the 3.42 axle which necessitated more use of the throttle at lower speeds.
I had a Pertronix fitted to supposedly cure slight wear in the distributor already.
It was getting to the stage that I just was not enjoying driving her and considering another marque.
However having just had a 123 distributor and electronic ignition fitted everything has cleared up and she is running superbly.
If anyone has any misfire issues I would recommend trying the 123. The cost is a very reasonable GBP 280 and its a brand new complete unit replacing the whole distributor.
Cruised down to Devon last Thursday at the legal limit at a relaxed 3500 rpm fuel use is much lower with the new axle and apart from a bit more throttle on acceleration I notice no downside to the new axle either apart from more relaxed cruising.
The car is just as I imagined she should be

[Peter van Es]

Congratulations Rob... now what kept you for so long?

Peter

[rob walker]

Me being in Turkey and the car in the UK and only getting to drive her the few days I could pick her up from storage. I am now back in the UK and Spain permanently and the car is with me.
Looking forward to the drive to sunny Spain on the 4th Oct

[Cees Klumper]

Congrats Robert - just to clarify one thing: you indicated in your post that you fitted a 123 ignition AND electronic ignition, but to my knowledge the 123 is both in the one unit, i.e. no separate electronic ignition required alongside the 123 - right?

Again, glad to hear the problem cleared up - as Dr Benz has told us before, fitting an electronic ignition unit like the Pertronics or Crane does not solve the problems caused when the Bosch distributor itself is worn out.

[geezer]

This one has peaked my curiosity.  I'm guessing that the 123 had a M110 engine.  I was down at the bone yard the other day and was looking at the distributor on a M110 engine.  It looked like a plausible swap.  So were there any problems with changing over the dist?

My '72 280 M130 engine has the aluminum Bosch dist.  The bushing is a little loose but livable for now.  Eventually I plan on converting to electronic ignition.  If the M110 electronic distributor will work, that just may be the answer.

The biggest issue that I see is that my distributor has a vacuum retard.

[Naj ✝︎]

Hello, geezer,

The 123 distributor being discussed here is a Bosch replacement made in Holland.
As you have found, there are a lot of testimomials here for it. (See wiki for details)

My car is running on a distributor from a M 110 engine. The diameter and dist. cap is bigger, but there is enough room for it. Some of them can do both vacuum advance and retard. There are take off pipes on both sides of the diaphragm. The housing and shaft are longer and need to be shortened. The ECU's have also proven to be quite bullet proof. I did it as an experiment with lots of help from the Technical Director of our UK MB Club. I changed back to an early throttle body from a 230 SL and am using both vacuum retard (when idling) and vacuum advance (while running). While, I do not have dyno tests, I believe it has more power in the mid range and will pick up in top gear from about 10 mph with no hesitation. There is also some improvement in mpg. (The tech Director has similarly used a distributor from a W201 190 E for his 1950s MB 170 and is aslo working with another member to convert a V8 distributor on a 6.3 M100 engine using one from a M117 I believe)

Unless you want to use one for a good reason, in my view, you are better off with a new 123.

naj

[geezer]

When I saw the 123 I was thinking a W123 chassis.  I found the 123 website.  It looks like they make a nice product.

http://www.123ignition.nl/index.php

[rob walker]

Cees you are correct its both the new distributor and electronic ingntion in one. Geezer, its the best thing I have ever bought for the car.

[PeterW113]

Hello Rob,

I am very interested in your experience with the 123 Ignition upgrade as this is something I have been considering for my 280SL.  My issues are two fold 1) mpg that appears to be sub 20mpg but I have never really confirmed this but more importanently a lumpy tickover. 

Having got stuck in heavy traffic the Blackwell Tunnel approach last night my  car was really struggling to tickingover. Tickover  ranged from 250 - 700rpm and ended up stalling once or twice, fortunately the rest of the traffic was very patient while I restarted.
The tickover speed was set at the last service so I have never questioned the speed although it seemed low.

I would be interested to know if:
1) Would the 123 assist providing a more consistant tickover.
2) What else should I explore
3) Is just that I have the tickover set to low

My car usually starts first time even when unused for a while and once on the move the engine is very sweet.

I you or any one else can assist I would be most grateful.

[Peter van Es]

Peter

First make sure your linkages are set correctly following all the advice in this extensive thread: http://www.sl113.org/forums/index.php?topic=5003.0

(If you are a full member you can find an easier to follow, condensed version of the Linkage Adjustment Tour in the Technical Manual).

Then read this thread for everything there is to know about the 123-ignition: http://www.sl113.org/forums/index.php?topic=9984.0

Peter

[PeterW113]

Peter,

Thank you for your advice, I am a full member of the Merecedes-Benz Club but not the Sl Group but I will follow the threads you suggest.

Many thanks for your help.

Regards

Peter

[Cees Klumper]

I would also (have your garage) check the idle air/fuel mixture. Idle RPM ('tickover') should be around 800-900; if mine idles lower it also has a tendency to stall. If you have not experienced this problem prior to the last service, and the idle RPM was higher before, I would guess that that is the cause of your problem.

Good luck with fixing this annoying problem.

[Eminent]

Because i'm very interested to buy a 123 ignition in the future i am following this thread. But can somebody tell me what a tickover is? 

[Brian Harris]

Tickover = Idle speed.

Cheers... Brian

[PeterW113]

Cees Klumber

Thank you to you and others for the responses, I am going to read my Haynes manual and the suggested threads this weekend and see if adjusting the idle speed solves the problem.

Regards

[rob walker]

Cees Klumber

Thank you to you and others for the responses, I am going to read my Haynes manual and the suggested threads this weekend and see if adjusting the idle speed solves the problem.

Regards

Peter see you are in London, it maybe worth your while popping into Roger Edwards and have them setup the car for the first time before you go the distributor route, but using the 123 has transformed the total running of my car!

[Eminent]

Well, hope to receive the 123 in the next few days.
The original ignition is not that good anymore. If i turn the rotor by hand it won't turn back easy.
This summer i opened the original one and replaced the springs.
The plastic sheets under the weights were too far gone to put back in.
So now it's metal on metal and i think thats the problem from turning back.
Also, when the car rolls out it start to misfire when it comes under 40 mph.
So, hope also to say soon that the problems are gone with the 123.
You'll hear from me.

[PeterW113]

Hi Rob,

I do use Roger Edwards, in fact the cars slow idle occurred following a Cylinder Head overhaul at RE, all very costly some two years ago, I should have headed back to RE's sooner to sort it out however a major house renovation at my home in SE3 got in the way.  My car went unsed for most of the time and now, RE has moved to Amersham, and funds are very short post house renovation hence I thought I would take the DIY route. I must admit having read the various articles all those rods and adjustment's looks pretty scary. Despite the slow idle speed I would recommend RE and use them again, I have now doubt had l been able to to get back to them they would have sorted it out.

I might just have to wait until  this reccession passes and head back to RE all the same.

Kind regards