1970 M130 US two-way switch problem

[Frank Reiner]

Originally Posted by bracurrie

Hence lower combustion temps at idle, correct?
If so then that is what I want. I assume an 051 curve w/ vacuum curve from a throttle body for the 051. I would either find a good 051 or a 123 configured appropriately.

Correct on the temps; more advance = lower temp.
"a 123"? Is 123 a distributor model #?, or, is it the M123 (2.5L) engine?
There may also be a distributor from the M114 engine that is configured with vacuum advance.

[bracurrie]

Originally Posted by Frank Reiner

Correct on the temps; more advance = lower temp.
"a 123"? Is 123 a distributor model #?, or, is it the M123 (2.5L) engine?
There may also be a distributor from the M114 engine that is configured with vacuum advance.

123 Ignition has a distributor that you can program the advance curve in software with either a bluetooth or USB connection. https://123ignitionusa.com/mercedes-6-cylinder-tune-6-r-v-m-programmable-bluetooth-will-not-fit-c-models/ It also allows for the input of vacuum to change timing.
Check out this post on the 113 Pagoda forum. https://www.sl113.org/forums/index.php?topic=23210.msg214545#msg214545

[bracurrie]

Please excuse my obsession with this topic and again thank you to all who have participated.
As a conclusion to everything I have learned I have decided to take the steps enumerated below. Because my car is a manual I do not need any distributor retardation.
1. Remove vacuum retardation system entirely and plug openings in throttle body and dizzy.
2. Set distributor timing appropriate for my 061 wo vacuum.
3. Disable MFI fuel cutoff solenoid.
4. Remove speed switch and relays that controlled two-way switch and fuel cutoff.
Eventually I will do the following:
5. Obtain and install a programmable 123 ignition distributor
6. Program the 051 curve wo vacuum. (I have a manual shift.)
7. Remove transistorized ICM

I will try to remember to update this thread with the results.
Brad

[Frank Reiner]

Originally Posted by bracurrie

Please excuse my obsession with this topic and again thank you to all who have participated.
As a conclusion to everything I have learned I have decided to take the steps enumerated below. Because my car is a manual I do not need any distributor retardation.
1. Remove vacuum retardation system entirely and plug openings in throttle body and dizzy.
2. Set distributor timing appropriate for my 061 wo vacuum.
3. Disable MFI fuel cutoff solenoid.
4. Remove speed switch and relays that controlled two-way switch and fuel cutoff.
Eventually I will do the following:
5. Obtain and install a programmable 123 ignition distributor
6. Program the 051 curve wo vacuum. (I have a manual shift.)
7. Remove transistorized ICM

I will try to remember to update this thread with the results.
Brad

bc:

Irrespective of the type of transmission, incorporation of load sensing capability in the control of the firing point is a very desirable feature.
With the exception of some MB systems of the early-to-mid 1970s that had vacuum retard, all others had vacuum advance. That advance feature was achieved either through a mechanical device on the distributor that moved the breaker plate, or, in the solid-state systems, via a piezoelectric manifold pressure sensing device.

In the case of your 061 distributor, when the vacuum device is disabled the idle firing point will need to be set to ~12 degrees BTDC to be able to achieve a total advance of ~32 degrees. Were a vacuum advance mechanism incorporated, a total of ~42-44 degrees would be available in low load situations, which would be dialed back towards ~32 as the throttle was progressively opened.
That vacuum advance feature is available in the "123" system.

[bracurrie]

Originally Posted by Frank Reiner

In the case of your 061 distributor, when the vacuum device is disabled the idle firing point will need to be set to ~12 degrees BTDC to be able to achieve a total advance of ~32 degrees. Were a vacuum advance mechanism incorporated, a total of ~42-44 degrees would be available in low load situations, which would be dialed back towards ~32 as the throttle was progressively opened.
That vacuum advance feature is available in the "123" system.

Is there any problem with ~12 BTDC?

How important to drivability is the ~42-44 degrees? In other words, Why is it desirable?

[Frank Reiner]

Originally Posted by bracurrie

Is there any problem with ~12 BTDC?

How important to drivability is the ~42-44 degrees? In other words, Why is it desirable?

12 degrees initial should be entirely viable; the only caveat will be to be conscious of pinging if the centrifugal advance comes up too quickly.

The extra light-load advance in low manifold pressure situations is of value in reducing fuel consumption. When manifold pressure is low, cylinder charging with fuel/air mixture is also low. Low density mixtures burn at a lower rate than high density mixture, consequently the combustion must be started earlier to have peak combustion pressure occur at the optimum point of piston position. Driveability is little affected; fuel consumption is.

[bracurrie]

Originally Posted by Frank Reiner

12 degrees initial should be entirely viable; the only caveat will be to be conscious of pinging if the centrifugal advance comes up too quickly.

To be safe I think I will go with the recommended 8 degrees. If I am understanding things and given the 061 advances ~23 degrees that would give me 31 degrees total advance at above ~2500 RPM.

Originally Posted by Frank Reiner

The extra light-load advance in low manifold pressure situations is of value in reducing fuel consumption. Driveability is little affected; fuel consumption is.

Hence either the need for the 051 compatible throttle body or the new hole modification of the 061 compatible throttle body so that you can either use an 051 or a 123 Ignition setup to behave like an 051.

[bracurrie]

A quick report for those following this thread. I got a friend who has a good timing light with RPM readout to come check where the distributor was currently set. It was at 5 degrees ATDC wo vacuum at idle which was 800 RPM. A change was made to 8 degrees BTDC wo vacuum which resulted in a 1000 RPM idle. At 2500 RPM advance peaked at 31 degrees. Leaving the switchover gear for retardation disconnected the car starts and runs much better but not perfect as I have a fuel supply problem that needs to be ironed out.
Thanks again to all that chimed in here. I have learned a lot.
Brad

[Benz Dr.]

You call that better? I remember telling you to leave everything connected and not to worry about the thermo switches. You are still lacking 7 - 8 degrees at full advance. Setting it to 12 degrees BTDC will make it ping so what are you going to do?

Your best option, outside of getting a 123 unit that you can control, is to get a 051 with matching throttle body that is designed to work with this engine.

[bracurrie]

Originally Posted by Benz Dr.

You call that better? I remember telling you to leave everything connected and not to worry about the thermo switches. You are still lacking 7 - 8 degrees at full advance. Setting it to 12 degrees BTDC will make it ping so what are you going to do?

Your best option, outside of getting a 123 unit that you can control, is to get a 051 with matching throttle body that is designed to work with this engine.

Dan, Yes I do call that better for me if only because the switchover gear isn't functioning properly, so with the vacuum disconnected from the dizzy it simply stays in the advanced state where it is anyway above 2400 RPM after the two-way switch interrupts the vacuum connection to the dizzy.

With the vacuum disconnected from the dizzy I am not losing any advance ( + 23 degrees), I am only losing retardation (- 17 to - 23 degrees). This is according to the data in the Service Manual where 30 degrees is the furthest advancement with the 061 dizzy set at 8 degrees BTDC WO vacuum at idle.
The 051 is clearly superior because under light throttle load it advances beyond 30 degrees, but under full throttle loads I believe it retards back to ~30 BTDC.
You keep stating that I am losing 7 - 8 degrees of advancement but if dizzy WO vacuum either by two way switch or by simply not being connected behaves the same way, I don't understand where the additional 7 - 8 degrees advance would come from just because vacuum is removed by two way switch.
I have a 123 Ignition dizzy in my future, just not right away. Looking for another 061 throttle body to modify to behave like an 051. Really want to ditch the transistorized ICM but retain better spark.
I will not advance the 061 beyond 8 degrees BTDC to be safe.

Brad

[Frank Reiner]

Originally Posted by bracurrie

Really want to ditch the transistorized ICM but retain better spark.
I will not advance the 061 beyond 8 degrees BTDC to be safe.

bc:

Unless the switchgear (ICM) is causing some problem that you have identified, it has value in that it greatly reduces the current across the breaker points, and thereby extends their life.

RE: Table in Post #23(?)
Note that the initial advance called out (cranking speed) is 10 deg BTDC.
That is a very conservative, safe initial firing point; 12 is entirely doable.
The curve in the 061 is quite short (~23 deg), so even at 12 initial there is only ~35 deg total.
Also note how far the carbureted version of the same engine advances; 37 centrifugal, & up to 49 w/vacuum!

[Benz Dr.]

I just rebuilt a 062 distributor today and I don't think how it actually functions is all that clear to the readers here.

First of all, the mechanical advance on the 062 is 20 degrees crankshaft and that's it. With the vacuum portion disconnected and regardless of where you set your idle timing, all you will get is 20 degrees more than that setting.
The vacuum portion is 11 degrees distributor or 22 degrees crankshaft. With vacuum connected and the engine at idle, the timing on this engine is usually set to roughly 2-3 degrees ATDC at about 800-900 RPM. As the engine increases in RPM, the mechanical portion will begin to advance up to 20 degrees or about 17 - 18 degrees BTDC due to idle timing. At this point, the mechanical advance is full and then the switch gear closes the switch over valve and the timing will move all in one shot 22 more degrees up to 38-39 degrees full advance which right where you want it.

Most distributors from that time period had 20 degrees of mechanical advance and only 10 degrees of vacuum advance. Vacuum advance or retard will give you the same amount of full advance regardless of which system you use and is determined by the distributor.

I have tried to run the 062 system on mechanical only and even with moderate initial timing it pinged badly. This system is designed with a very large amount of vacuum movement so that the distributor can swing into the ATDC timing area to reduce emissions at idle speed. Since you are loosing 22 degrees of timing without vacuum function it will never really run well. That last 7 or 8 degrees of full timing is where all the power is.

Fix this system, change to a 123 distributor, or go back to a 051 with a proper throttle body and set your idle timing to 8 degrees BTDC. You should change to a red coil with 1.8 ohm ballast resistor if you go to a 051 unit because the blue coil is meant for the CD type ignition.

One thing you should note:
dwell angle on the 062 is 30 degrees and not 38 degrees as found on the earlier cast iron units.

[bracurrie]

Originally Posted by Frank Reiner

bc:

Unless the switchgear (ICM) is causing some problem that you have identified, it has value in that it greatly reduces the current across the breaker points, and thereby extends their life.

RE: Table in Post #23(?)
Note that the initial advance called out (cranking speed) is 10 deg BTDC.
That is a very conservative, safe initial firing point; 12 is entirely doable.
The curve in the 061 is quite short (~23 deg), so even at 12 initial there is only ~35 deg total.
Also note how far the carbureted version of the same engine advances; 37 centrifugal, & up to 49 w/vacuum!

I am going to stay with ICM until I get the 123.
I wondered why cranking speed advance would be different from idle speed.

12 may be doable, but if I get stuck with less than ideal octane fuel I dont want to risk pinging.
From the Table in Post #23: What I can't figure out is what is safe full throttle advance at 2500 RPM. I assume that low 30s is, but looking at 280 S you got to wonder.
BTW now that I have the fuel supply problem solved (plugged fuel filter) the car pulls nicely at full throttle from less than idle to all the way to near redline.

[bracurrie]

Originally Posted by Benz Dr.

I just rebuilt a 062 distributor today and I don't think how it actually functions is all that clear to the readers here.

First of all, the mechanical advance on the 062 is 20 degrees crankshaft and that's it. With the vacuum portion disconnected and regardless of where you set your idle timing, all you will get is 20 degrees more than that setting.
The vacuum portion is 11 degrees distributor or 22 degrees crankshaft. With vacuum connected and the engine at idle, the timing on this engine is usually set to roughly 2-3 degrees ATDC at about 800-900 RPM. As the engine increases in RPM, the mechanical portion will begin to advance up to 20 degrees or about 17 - 18 degrees BTDC due to idle timing. At this point, the mechanical advance is full and then the switch gear closes the switch over valve and the timing will move all in one shot 22 more degrees up to 38-39 degrees full advance which right where you want it.

Most distributors from that time period had 20 degrees of mechanical advance and only 10 degrees of vacuum advance. Vacuum advance or retard will give you the same amount of full advance regardless of which system you use and is determined by the distributor.

I have tried to run the 062 system on mechanical only and even with moderate initial timing it pinged badly. This system is designed with a very large amount of vacuum movement so that the distributor can swing into the ATDC timing area to reduce emissions at idle speed. Since you are loosing 22 degrees of timing without vacuum function it will never really run well. That last 7 or 8 degrees of full timing is where all the power is.

I am trying to understand your point that the 061 is capable of 38 degrees of advance and it doesn't square with the Service Manual. According to the Service Manual initial timing is set at 10 degrees BTDC WO vacuum which would result in maximum advance of 10 + 20 or 30 degrees WO vacuum. Because the vacuum only retards 17 to 23 degrees how can 061 deliver more than the mechanical advance when vacuum is removed?
From the book: At cranking speed 10 degrees BTDC, at idle with vacuum 8 degrees ATDC, at 3000 RPM 25 - 30 BTDC with vacuum however vacuum is disconnected at this RPM via speedswitch. Then this makes sense as +20 degrees is all you get from the mechanical advance. And because there is no vacuum advance on the 061 30 degrees BTDC is all you get (10 + 20).

[Benz Dr.]

I give up. (sigh) Go back and read what I posted and forget the service manual. It's written for MB mechanics and has a lot of info that is sometimes useless or very confusing to the average DIY guy. They include with and without vacuum which confuses just about everyone who thinks 30 degrees is full advance when they forget about adding idle timing. So they set everything to 30 degrees and think they have it down.

Close to 40 BTDC is safe after 2,500 RPM. Most distributors are pretty much fully advanced at or near that RPM and some even have an extra advance curve above 4,000 RPM of several more degrees.

You should run 91 octane in your engine