Distributor replacement from 123 ignition

[Cees Klumper]

quote:Originally posted by Martijn

Cees,
Unfortunately I don’t have CO-meter at my disposal. But I will read the linkage tour this weekend carefully. Thanks for the tip, though.Martijn

Hello Martijn - the CO value at idle (FI pump adjustment using the slotted screw, in combination with the large screw on the intake manifold) is important to get right. Not really difficult but you do need a CO analyser; if you want to use mine (a British Gunson unit) just let me know, I am in Amsterdam so not too far from where you are located.

[Ziggy]

I know everything of the Mercedes 123 as I was involved in its development...
Can you actually have a reliable reading with that Gunson thing? I thought it had to warm up first for like 10 minutes, and then it takes something like 90 seconds to read any adjustment?

[Cees Klumper]

quote:Originally posted by Ziggy

I know everything of the Mercedes 123 as I was involved in its development... Can you actually have a reliable reading with that Gunson thing? I thought it had to warm up first for like 10 minutes, and then it takes something like 90 seconds to read any adjustment?

Good to hear you know all about it. I left my red coil in place given your earlier comments.

Yes, the Gunson apparatus gives realiable readings or at least I have confidence that it does. It does take time to calibrate, 8 minutes I think to be exact, which is negligible considering the thousands of miles and time associated with that distance that I spend in the car between tune-ups.

[jameshoward]

Gerard/Cees,

I am sorely tempted. Did you have to do the grinding thing previously mentioned or did you manage to install it without going down that route?

Could you also confirm whether I would be able to use the same model you purchased for your 280 with my 230? Could you please post the model number if you have it? I think, because I'm in Germany, I would end up purchasing it direct as I don't know Van Dijks (but if you have a phone number for them I could ask if they'll ship).

Sorry to bombard you with questions,

James

[Ziggy]

James, there is no grinding required to install the 123. You need the same model as Cees, the 123-6 cylinder, the other 2 models being the 123-4 cylinder and the 123-6-old which is for models from the 50's. (don't have specific information about the last one as it was made afer my time)
In Germany you could order it from www.dbdepot.de , among others.

Cees, I didn't mean the initial calibrating (professional CO meters also do that, just for a minute) but how long does it take the Gunson to detect a change in the CO when operating? Professional meters also have a delay of a couple of seconds, but I think the Gunson needed something like 1 1/2 minute.

[jameshoward]

Ziggy,

I am confused (a not uncommon feeling) because if you go to page 2 of this thread you will see this entry, together with another entry that has a diagram of a collar that I thought needed to be removed.

Is this not so?


 

quote:Naj,
$700 is what it cost me including tax, shipping and modification of the unit. The unit needs a minor modification for our cars. This involves cutting or grinding off part of the "base" of the distributor "cup" where it sits on the collar of the distributor housing upon insertion, in order to avoid seating interference by the sleeve of the 5mm hex clamping bolt. While the unit will still function without this mod, the dog will only partially seat in the drive.

James

[gwuisman]

Cees,
Happy driving with the 123!

James,

I bought the system at http://www.oldtimer-motoren.de/ . They have a lot of experience in building it in. In my case some calibration of the gas rods, airscrew ect. was necessary to get the optimal result.

Gerard
1971 280sl

[Martijn]

This evening I replaced my new blue coil for my old black coil again. Like Ziggy advised me, the original black coil should be better. I measured the resistance of the black coil: 2.4 ohm. The blue coil is 3.4 ohm.
The cold start of the engine seemed to be a bit better, but I didn't have the time yet to test it much. Perhaps I will buy a red coil because of your positive experiences.

After that I examined the linkage like James suggested. It turns out that some ball joints are worn. Some rods have about 1 mm play in the joints! I have to order new ones before adjusting the linkage, I think.

Cees, thank you for your offer for using your CO analyser. I would like to take up your offer. Besides that, it would be nice to meet a fellow member. And meeting the president makes it even more special    But I think it's wise that I should fix the ball joints first.

Martijn

[Cees Klumper]

quote:Originally posted by jameshoward

Gerard/Cees,
I am sorely tempted. Did you have to do the grinding thing previously mentioned or did you manage to install it without going down that route?

Could you also confirm whether I would be able to use the same model you purchased for your 280 with my 230? Could you please post the model number if you have it? I think, because I'm in Germany, I would end up purchasing it direct as I don't know Van Dijks (but if you have a phone number for them I could ask if they'll ship).

Sorry to bombard you with questions,

James

I did not have to grind anything down or turn a collar upside down, because on my engine the clamp is integrated into the housing that bolts onto the engine block and is flat on top. In other words, the 123 unit dropped right in without any modifications. The model number is 123\MERCEDES-6-R-V. It's the same unit for 230, 250 and 280 SL's.

Here is an image of what it looks like at another seller in The Netherlands (EUR 300): http://www.leenapk.nl/product_details.php?category_id=54&item_id=4

Here are the contact details for Van Dijk:

Van Dijk, the Classic Mercedes "SL" specialist
Kruisbaak 24
2165 AJ Lisserbroek
The Netherlands, Europe
Tel.: 0031-252-423713
Fax.: 0031-252-422758

E-mail: vandijk@classicsl.com

[Cees Klumper]

Update: now having driven a couple hundred miles with the 123, I can say it works very well. When starting in the morning, the engine is quieter. When warm, the engine seems to run smoother. I am measuring fuel consumption and so far it's been less than average (although that is also dependent on the kind of driving - long or shorter trips, speeds driven etc) so I will have to measure over a longer period of time for that aspect.

[J. Huber]

Hey all. If I am following this all correctly, the 123 is different from Crane and Pertronix in that it is the entire dizzie versus just innerds. But similar in that its electronic versus points. Is that right?

And on install, does it just drop into the existing Dist. housing -- then you set the timing? (having dealt with the grinding or flipping of collar, etc.) Would that mean you could just lift off the old distributor (in my case with points) and keep it as a back-up -- again just dropping it into place? Or am I missing something?

[Cees Klumper]

quote:Originally posted by J. Huber

Hey all. If I am following this all correctly, the 123 is different from Crane and Pertronix in that it is the entire dizzie versus just innerds. But similar in that its electronic versus points. Is that right?

And on install, does it just drop into the existing Dist. housing -- then you set the timing? (having dealt with the grinding or flipping of collar, etc.) Would that mean you could just lift off the old distributor (in my case with points) and keep it as a back-up -- again just dropping it into place? Or am I missing something?

Yes, the 123 is a complete ditributor that has minimal mechanical parts: no points, and no flyweights/springs etc for the advance/retard adjustments, all that is electronic. You can set the advance curves by adjusting a microswitch.

In my case, since I don't have a separate clamp to hold the distributor in, it dropped straight in; static timing was done by rotating the distributor until a small green led inside the distributor came on. Then fine-tuned with a strobe light (but the static procedure put it within a few degrees of where it needed to be).

I kept the original coil and bypassed the ballast resistor.

The timing is very stable, as shown by the strobe light revving the engine to different RPMs.

[jacovdw]

quote:Originally posted by J. Huber

And on install, does it just drop into the existing Dist. housing...

James, it is just that simple - all you have to do is drop her in! That is after you flipped the collar (a more elegant solution). With our early 230SL's, we would have to flip the collar, since it is different from the setup used in the later 280SL's as Cees mentioned.

I am also following this thread with interest. Even though I am happy with my Pertronix setup (for now), the bug has bitten. Can always use the old setup as a backup.

Now to find a distributor for this 123 ignition in SA...

[Cees Klumper]

That is what I figured, I will carry the original distributor with electronic addition I was using as the back-up.

I received the invoice from Van Dijk and they charged EUR 380 for the unit, which this other company sells for EUR 299 - so no offense to Van Dijk, but if I were you Jacco, I would email this company and order it through them. The unit comes complete packaged so there's nothing that a reseller adds, just the markup for their trouble. This website has English language as well:

http://www.leenapk.nl/product_details.php?category_id=54&item_id=4

[jameshoward]

On pricing, and given the fact that the Euro is so expensive at present, I've found it in the UK for GBP 200 less tax. Some people might find it cheaper to purchase from there. The company is called Southern Carbueretters and is listed as a distributor (relevant pun) on the 123 site.

JH

[Paddy_Crow]

Has anyone in the US bought one of these units? Where did you get it?

[awolff280sl]

I put the 123 in a few months ago. Got it from:
Brooklyn Motoren Werke, Inc.
115 Market Street
P. O. Box 198
WS 53521 Brooklyn
tel: 608 455 7441

I'm happy with it.

[J. Huber]

So bear with me here -- when you all mention a more stable timing -- you mean among other things that when the strobe light is on 30 BTD @ 3000 it is steady not bouncing a bit? And if so, does that equate to better performance? Reason I ask is: I have had no trouble with points -- but I do notice that when I set the timing, there is some bounciness.

[Cees Klumper]

Hello James - yes, a more steady timing at higher RPMs than with the old distributor. I've driven some more and it does seem smoother and more powerful. Difficult to really be sure without good before-and-after measurements on accelleration etc but I do believe that having a brand-new, high-tech distributor that uses electronics rather than mechanicals eliminates possible causes of sub-optimal performance, especially on our old cars.

[Eminent]

So how did you guys do the fine tuning?
Step 5 from the 123-ignition manual says: Disconnect the vacuum-tube whilst finetuning.
The Haynes manual says to keep vacuum connected.

[jeffc280sl]

James,

I recently updated the tech manual section having to do with a points ignition system.

"As the engine spins the Distributor shaft, there is a 6 lobed cam mounted to the distributor shaft. Just off of the cam is a single set of breaker points that open and close by the distributor cam's contact with the point set(s). When the points are closed, they allow the coil to energize and store energy. When the points open, the stored energy is released as high voltage energy through the rotor, cap, the high tension wires to the spark plugs. How long the points stay closed is the 'dwell' or dwell angle.

At ordinary engine operating speeds, the points open and close a couple of hundred times per second, the exact number depending on the number of cylinders and the engine RPM. The points need to be closed for a appreciable time in order to build up the maximum magnetic flux in the ignition coil core.

The period of points closure is specified by the ignition system designer and is typically expressed as degrees of distributor rotation. In a six cylinder engine, the angle between each ignition cam lobe is 60° and the period of points closure or "DWELL" is usually a 30° to 35°.

Dwell is adjusted by setting the points gap to a specified distance at maximum opening. A narrower gap gives more dwell and a wider gap gives less. Taking it to extremes, excessive dwell means that the points close too soon after opening, cutting off the magnetic field collapse in the coil before it delivers all its energy. Too little dwell gives the magnetic flux insufficient time to build up to the maximum.

Both conditions give a weak spark which gets even weaker as the engine RPM rises and produces misfiring at normal operating speeds. The dwell, as well as spark plug gap, do have an effect on ignition timing.

The later the points open, the later the spark comes and retards the timing. The earlier the points open the sooner the spark comes and advances the timing. That is why TIMING IS THE LAST THING TO BE SET IN A TUNE UP. "


When you adjust timing with a strobe light you are fine tuning any advance or retard variance from the dwell angle.  As the dwell angle changes (points wearing) timing also varies.  You are seeing the the results of a failing distributor with the varying timing of your car at 3000 rpms.