123 Distributor

[Ziggy]

Bob, I was involved in research and development of the Mercedes 123. It was never designed to include the emission control as found on US Mercedes at the time. Since such emission control devices are considered redundant on such old cars overhere, this was something you just disconnect when installing the 123, I don't think anyone expected actually someone wanting to keep that working.
So any method of keeping the emission control working with the 123 is not original or designed by the manufacturer. I don't know much either about keeping emission control properly working so I can't help you with that. When US Mercedes are imported back this is usually the first thing to be removed or disconnected.

[bpossel]

Thanks Naj & Ziggy!

Ziggy, that is sooo cool that you were involved with the R&D of the "123" and we have you with us on this forum  !

Can you further explain how I should install the "123" on my later 280sl especially with the throttle body that is on my car?  Should I simply run the "123" vacuum line direct to the throttle body and not through the 2-way valve?  Then disconnect the 2-way valve and relays for emission control?

It's the throttle body version that is the real question... Can I use my current throttle body?

Another question is the need for a longer spring.  I received an email direct from Aryan at "123" who stated NOT to use a longer spring.  He said the longer spring will cause the 123 to wear quicker (use the original 20mm OE spring).  Can you comment on this?  What is your opinion, especially since the 123 has a 10mm recess hole in it's bottom and 1/2 of the OE spring sits inside the 123 unit.

Thank you very much!
Bob 

[waqas]

Apologies for the interjection here, but perhaps I'm the only one who gets confused whenever there's any discussion about the 123 distributor.

From what I understand, there are the 123 chassis Mercedes cars from the late 70s to the mid 80s. These came with distributors that can be found at dealers and many other suppliers. (made by Bosch presumably?)

Then there is the "123 distributor" which is a specific [non-Bosch?] product (with pre-programmed advance curves and whatnot) which is sold through specialized dealers.

Is it correct to assume however that the "123 distributor" was never original equipment in any 123 chassis Mercedes car?

Thanks in advance for clarifying my "misunderestimation"... 

[bpossel]

Hi Waqas,

You are correct.  We should probably move this "123" discussion to the "123" postings...
Bob 

[Peter van Es]

I've merged the topics.

I'm getting a lot of private questions on the vacuum line and the throttle body. I am fairly certain I have a throttle body as in the last picture in the Tech Manual (http://www.sl113.org/wiki/pmwiki.php?n=Fuel.Throttle)-- i.e. the most recent, as for a 1970/71 SL -- and my vacuum line is connected in that same spot as in that picture. It's a bit hard to check at the moment as my car is parked against the wall and I'm hesitant to take it out currently with the bad weather. I've just  checked it and can confirm.

I checked my vacuum line, and it is connected normally to the 123-distributor, and the air intake housing at the other end... NOT on the venturi side. That inlet is closed off with some sort of screw in the hose. To see what emissions control stuff has been removed on my engine, check this thread: http://www.sl113.org/forums/index.php?topic=10066.0

Naj presumed:

At this point in the venturi, there is a vacuum signal all the time the engine is running. So, the centrifugal advance would advance the timing with engine speed but the vacuum would retard it, and the engine would not run well and lose power. So, what have they done to take care of this? There could be an eloborate chip in the distributor to adjust vacuum retard according to engine speed, but I doubt it. So if you do have the latest body, what was done? One idea is to block the vacuum completely, and I guess you would not know any different!

Read the 123 manual in one of the posts below, or the 123 website.  There IS a very advanced, microprocessor in that device. See the picture of one opened below. It has a selector switch to select one of 16 different parametric patterns / curves. It knows engine speed and it has the vacuum line connected... but I have no idea how it works internally other than that.

I experience NO power loss at all, in fact the engine feels really excellent with the 123 distributor.

If you need to know more, I suggest you post questions on the 123-forum, http://www.123ignition.nl/forum/. It is excellent, and frequented by the designers of the device. They'll be able to answer all your questions much more accurately!

Peter

[Naj ✝︎]

I checked my vacuum line, and it is connected normally to the 123-distributor, and the air intake housing at the other end... NOT on the venturi side. That inlet is closed off with some sort of screw in the hose.

Peter

Can you post a picture showing:
 'NOT on the venturi side. That inlet is closed off with some sort of screw in the hose'

Thanks
naj

[Peter van Es]

Naj,

that quote was in response to a question from Bob in the emissions control topic. I just checked my throttle body (squeezing past in the garage) and it it EXACTLY as the last photograph in the Tech manual (http://www.sl113.org/wiki/pmwiki.php?n=Fuel.Throttle) and the vacuum line is connected like that too.

Peter

[Ziggy]

Ziggy, that is sooo cool that you were involved with the R&D of the "123" and we have you with us on this forum  !

Can you further explain how I should install the "123" on my later 280sl especially with the throttle body that is on my car?  Should I simply run the "123" vacuum line direct to the throttle body and not through the 2-way valve?  Then disconnect the 2-way valve and relays for emission control?

It's the throttle body version that is the real question... Can I use my current throttle body?

Another question is the need for a longer spring.  I received an email direct from Aryan at "123" who stated NOT to use a longer spring.  He said the longer spring will cause the 123 to wear quicker (use the original 20mm OE spring).  Can you comment on this?  What is your opinion, especially since the 123 has a 10mm recess hole in it's bottom and 1/2 of the OE spring sits inside the 123 unit.

Indeed, there is no need for a longer spring. Installation of the vacuum line of the 123 is very simple (that is why they called it "123", as in 1-2-3 installation) you just connect it to the throttle body. There is no need ever to change throttle body, there are several different curves for both advance and retard depending on your engine/throttle body.
If your emission control is connected to the same vacuum port you can use it as well by using a T piece tube, as long as the vacuum tube of the 123 is directly connected to the throttle body. But personally I would just disconnect any emission stuff.
When you have installed it you can verify proper operation with a timing light, on 1500, 3000 and 4500 rpm with and without vacuum.

[bpossel]

Thanks Everyone!
Peter, thanks for combining the posts...
I look forward to getting the 123 setup this weekend and taking pics and notes for the manual.
Lots of great advice and input on this!
Thanks again!
Bob 

[Peter van Es]

Can you post a picture showing:
 'NOT on the venturi side. That inlet is closed off with some sort of screw in the hose'

Thanks
naj

Here it is... pardon my un-detailed engine bay. On the picture of the Throttle Body you can see the (new) vacuum line (white) run into the Throttle Body on the right hand side (looking from the driver seat to the front of the car), over the top, into the black rubber hose. Right on the opposite side of the Throttle Body (the lefthand side) you see a short rubber hose closed off with the screw. That's what I was referring to.

Peter

[Naj ✝︎]

Thanks, Peter,

Could be a vacuum test port for tuning???

naj

[bpossel]

Thanks, Peter,

Could be a vacuum test port for tuning???

naj

Naj,
That port is used for a idle lifting (vacuum cell, #3 on the diagram below) on the later cars with automatic.  It helps to lift the idle a bit when you put the automatics in gear.  When I had my IP pump rebuilt, they performed a Bosch Service Bulletin procedure on the IP Pump which came out in later 71/72? which allows for the omission of this vacuum cell and still maintain a nice idle in gear.  See tech manual for more detail.

[bpossel]

Update 1/31...

I set the "123" curve setting to "E" for the "062" bosch distributor.
I installed an earlier bosch coil (1,8 ohm), and connected the distributor directly to the coil (no ballast resistors).
Connected the "123" vacuum directly to the throttle righthand side (I plugged the left side hole).
I removed all of my emission control stuff:
2 black boxes; 2-way valve; current relay; disconnected the 17 & 100 degree switches; disconnected the fuel shut-off solenoid on the IP Pump.
Set timing to 30@3,000 rpm without vacuum. When reconnect the vacuum, it settles to "0" @~1,000rpm.  When I put the car in gear, idle drops to ~800rpm.
Initial test drive was very nice!  It seems to have a lot more pick-up and only a very slight bit of burbeling when coasting downhill, a nice sound! It seems to shift smooth on acceleration and downshift nicely.
Only time will tell and I need to do some more testing, but so far so good!
If all continues to go this smooth, I will pack up the emission control stuff and save for the next owner....
More to come...
Bob 

[Peter van Es]

Bob,

I'm so pleased you're pleased after all this... what did you do with the spring? The original or a longer one?

I went for a nice drive today, it was cold (freezing) but sunny and dry, and I took my Pagoda out for a 60 km spirited drive... I'm also pleased with my 123 ignition... started straight away when cold and restarted an hour later (warm) after a bit of shopping -- I had to get groceries for an Italian meal for 8 people that I cooked tonight (recipies on request) -- with my rebuilt injection pump pickup is excellent across the entire rev range, and accellerating onto the motorway, up to 5000 revs (155 km/h, a bit over the speed limit, but only for short distances) is fun.

So Bob, keep test driving... or whatever excuse you need!

Peter

[Ziggy]

You will be Happy with the 123 Bob. I know, I have been using it for over 5 years on a daily basis, and have made more miles with it than everybody combined on this forum with one. As a nice side effect your milage will increase by about 10% (if you didn't already have transistorized ignition and while keeping the same driving habits)
But since you also disconnected the emission control, if you want it to run better/have more power I would use curve #8.

[Ziggy]

Hi 66,
Yes, the benefits are the same for every model supported, if they already haven't transistorized ignition (early electronic ignition). But the 230SL never had that.
If you have transistor ignition the milage increase will be very small.

But I will tell you a secret, the technical manual on this site states an aftermarktet transistorized ignition would "not be practical and costly".
This is not so, for about 20$ you can get an universal transistor ignition, which also will get you a ±7,5% power and milage increase.
I have built these in a lot of vintage Mercedes, and it really is a must.
The 123 ignition is something when your old distributor is really worn, but if it is only normal wear the most economic thing to do is an universal.
 

[bpossel]

Naj, Ziggy,

Changed the curve setting to "8" as suggested.  Set timing to ~30@3,000 w/o vacuum.
Idle is set to ~900 (out of gear) @ "0" with vacuum connected
When engage gear, idle drops to ~800.
With vacuum connected I am getting a max of ~20@3,000rpm.  I reach the max ~20@~2,000 rpm.
Bob 

[Naj ✝︎]

Bob,

I would say this curve is not good for your application.

The vac is retarding the timing at 3000 rpm.

Did the same thing happen with the 'E' curve?

naj

[Ziggy]

It's odd Bob, since at 3000 rpm there should be no vacuum. At that point it doesn't matter which curve you select.
Are you sure you did it right? If so, connect the vacuum and turn the distributor to 30@3000. Then verify the settings at the other rpm's.

These are the official specifications:
051, no vacuum 2-4atdc@800, 12-19@1500, 30@3000
062, with vacuum 8atdc@800, 0-5btdc@1500, 25-30@3000

The 051 has a 10 degree vacuum retard and the 062 20 degrees. I'm not sure why they specify to check the 062 with and the 051 without vacuum.

for Waqas

[bpossel]

Thanks Ziggy, I'll have another go at it tomorrow evening....  I'll recheck and set 30@3000 with vac and see what the lower rpms look like...
Bob 

[bpossel]

It's odd Bob, since at 3000 rpm there should be no vacuum. At that point it doesn't matter which curve you select.
Are you sure you did it right? If so, connect the vacuum and turn the distributor to 30@3000. Then verify the settings at the other rpm's.

These are the official specifications:
051, no vacuum 2-4atdc@800, 12-19@1500, 30@3000
062, with vacuum 8atdc@800, 0-5btdc@1500, 25-30@3000

Ziggy & Naj,
With "123" curve set at "8", here are the readings:
30@3000 w/o vacuum
20@1500 w/o vacuum
5@1000 w/vacuum
Then 20@3000 w/vacuum (20 was the max it would go)

Reset to curve "E", here are the readings (much the same as "8":
30@3000 w/o vacuum
20@1500 w/o vacuum (idle)
adjusted to 10@1000 w/o vacuum (idle)
then connected vacuum and got 0@1000 w/vacuum (idle) --- ~800rpm in gear
rechecked and only get a max of 20@3000 (20 was the max!)

At this point I quit for the night.... 
Bob 

[Ziggy]

From this information, I would say the 123 is properly functioning. However, the timing is about 10 degrees off. Have you tried setting the timing to 30 with vacuum at 3000 rpm and then verify the timing at 1500 and ±800 (also with vacuum)
Can you feel any suction at the tube at 3000 rpm?
Are you sure you are using the right timing scale? I think your engine has the dual type timing scale with the late (triangular) pointer. In this case you must use the inner scale (towards the engine)

[bpossel]

Hi Ziggy,

Yes, I am using the inner scale, closest to the engine. When I set the timing to 30 w/vacuum, my idle was then ~1500@15.  I then rotated the 123 and dropped it to 5@1000 w/vacuum.  Next I retested at 3000 with vacuum, and the max I got was 20.  So you are right....  there is an extra 10 in the equation...?  Any add'l suggestions?
Thanks!
Bob

[Ziggy]

 
When you set the timing to 30@3000 with vacuum, and you disconnect it, what happens then? And when you reconnect it?

Have you also tried the official 1-2-3 method as described in the manual ? What timing do you get with that?

[bpossel]

Hi Ziggy,

I will do that test tomorrow and let you know.. thanks!!
Bob