1970 M130 US two-way switch problem

[bracurrie]

Originally Posted by 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

Dan,
Thanks for trying. But I am not the average DIY guy, I am actually used to learning in depth about new things. If there is a contradiction in the information I will not let it go until I understand it. I respect that you are convinced of your information but I thought we weren't communicating. I just don't want others to end up confused.
BTW I am running ethanol free 93 unless I am on the road and cannot find any. There is a noticeable difference with 91 ethanol.

[Benz Dr.]

Originally Posted by bracurrie

Dan,
Thanks for trying. But I am not the average DIY guy, I am actually used to learning in depth about new things. If there is a contradiction in the information I will not let it go until I understand it. I respect that you are convinced of your information but I thought we weren't communicating. I just don't want others to end up confused.
BTW I am running ethanol free 93 unless I am on the road and cannot find any. There is a noticeable difference with 91 ethanol.

Seems like I'm trying to keep others from being confused and you sort of got caught up in the mix. lol

The main thing to remember is that vacuum retard is set to 0 degrees of advance at idle. On some engines with a 051 distributor, advance will start right off idle as soon as the throttle valve opens and vacuum falls off. With the 062 the vacuum portion of the distributor will remain at 0 until the switch over valve closes and then you will get 22 degrees of advance all at one time.
Below 2,200 RPM the switch over valve opens and the vacuum portion returns to 0. At 2,200 RPM the mechanical portion of your distributor will still be advanced fully and it will return to idle timing ( 3 ATDC ) at your idle speed.

MB did this so that they could have a larger overall timing advance curve. This unit has close to 42 degrees of timing available so that idle timing can go into ATDC and still have proper timing for higher RPM over 2,500.

A 051 distributor has 30 of advance and you have to set your idle timing to 8 degrees BTDC to obtain proper top end performance. There is no option to go into ATDC with a 051 because the engine would probably stall and have terrible performance.
While your 062 may, or may not be working, or work great, the initial concept was certainly interesting.

[bracurrie]

Originally Posted by Benz Dr.

Seems like I'm trying to keep others from being confused and you sort of got caught up in the mix. lol

The main thing to remember is that vacuum retard is set to 0 degrees of advance at idle. On some engines with a 051 distributor, advance will start right off idle as soon as the throttle valve opens and vacuum falls off. With the 062 the vacuum portion of the distributor will remain at 0 until the switch over valve closes and then you will get 22 degrees of advance all at one time.
Below 2,200 RPM the switch over valve opens and the vacuum portion returns to 0. At 2,200 RPM the mechanical portion of your distributor will still be advanced fully and it will return to idle timing ( 3 ATDC ) at your idle speed.

MB did this so that they could have a larger overall timing advance curve. This unit has close to 42 degrees of timing available so that idle timing can go into ATDC and still have proper timing for higher RPM over 2,500.

A 051 distributor has 30 of advance and you have to set your idle timing to 8 degrees BTDC to obtain proper top end performance. There is no option to go into ATDC with a 051 because the engine would probably stall and have terrible performance.
While your 062 may, or may not be working, or work great, the initial concept was certainly interesting.

My 061 works fine. The retardation system is wonky, thus evaluating whether to go with out retardation, fix OE system or go with 123 ignition.

I just had no idea the Service Manual was so wrong. I was thinking that the mechanical advance was limited to ~20 degrees and the retard was good for ~20 degrees. So with an 061 if set at 10 degrees BTDC WO vacuum or 5 degrees ATDC w vacuum at idle then at 2200 RPM before speedswitch turns vacuum off timing ~5-10 BTDC then above 2500 RPM all at once retard of ~20 degrees is removed via two way switch and the result is ~38 BTDC. What I don't understand is where does the extra 8 degrees of advance come come from?

BTW what is the difference between an 061 and an 062 distributor? Service Manual says they are the same, but given other errors I wonder.

[Benz Dr.]

Originally Posted by bracurrie

My 061 works fine. The retardation system is wonky, thus evaluating whether to go with out retardation, fix OE system or go with 123 ignition.

I just had no idea the Service Manual was so wrong. I was thinking that the mechanical advance was limited to ~20 degrees and the retard was good for ~20 degrees. So with an 061 if set at 10 degrees BTDC WO vacuum or 5 degrees ATDC w vacuum at idle then at 2200 RPM before speeds witch turns vacuum off timing ~5-10 BTDC then above 2500 RPM all at once retard of ~20 degrees is removed via two way switch and the result is ~38 BTDC. What I don't understand is where does the extra 8 degrees of advance come come from?

BTW what is the difference between an 061 and an 062 distributor? Service Manual says they are the same, but given other errors I wonder.

I believe that the 061 and 062 are basically the same and there are differences in how they're made but not how they work.

The mechanical advance portion is 20 degrees - you have that right. The vacuum portion is about 22 degrees and is a fixed amount meaning it can't be changed because it's built into the system.
If you set your idle timing to 3 degrees ATDC, the mechanical advance portion will advance to 17 degrees BTDC and that's it. You can buzz your engine to 6,000 RPM and you will still only get 17 degrees BTDC.
At or around 2,200 - 2,500 RPM, the speed relay will trigger the vacuum switch over valve to close and without a vacuum signal going to the distributor the spring inside the vacuum cell will force the distributor to advance 22 degrees. This movement is very quick and you can hardly feel it while driving. 17 + 22 = 39 and that's about where your full advance timing will be with a functional system set at 3 degrees ATDC.

The speed relay will sense that your engine is below 2,500 and it will send a signal to the switch over valve and it will apply vacuum to your distributor as yo return to idle. You really don't need 38 degrees of advance below 2,200 RPM and that was designed into this system. It turns on and off when you need it.

One of the problems with running ignition timing ATDC is that it will make your engine run hot.They added a 100c switch but I find it's too little too late.

If you have constant vacuum going to your distributor and the vacuum system isn't working, it's not really any kind of system at all. If the switch over isn't working only the mechanical portion will make your distributor advance and that's 20 degrees. Depending on where you set your idle timing, you could have anywhere from 17 - to as much as 30 degrees BTDC at full mechanical advance. If you set your timing to 10 degrees you will get 30 full and - 3 degrees you get 17.

It's unlikely that the work shop manual is wrong.

If your switch gear isn't working you can get a 123 distributor that you can program to mimic the way the 061 works.

[bracurrie]

Service Manual says dizzy should be at 8 degrees ATDC w vacuum at 800 RPM. Because at cranking speed dizzy should be at 10 degrees BTDC wo vacuum. The amount of retardation is approximately 20 degrees because at 800 RPM a couple of degrees of mechanical advance is present. At no load w vacuum at 1500 RPM dizzy should measure at 0-5 degrees BTDC which according to the curve chart reflects approximately 10 degrees of mechanical advance while remaining under the influence of approximately 20 degrees of retardation.
This is where I get confused because the Service Manual states that w vacuum at 3000 RPM advance should be 25-30 BTDC. But there should be no vacuum retardation at 3000 RPM because the speed switch should have cancelled the retardation at about 2500 RPM. With no entries in the chart for higher RPMs I would infer from the chart that 25-30 BTDC is the highest resulting advancement. There is some logic here that makes sense to me. 10 degrees BTDC at cranking speed with 20 degrees of mechanical advance which tops out at 2000 RPM results in 30 degrees total advance at 3000 RPM.
Retardation at 800 RPM from 10 degrees BTDC to 8 degrees ATDC and at 1500 RPM from 20 degrees BTDC to 0 degrees.
When engine is cold or too hot then the engine is running in only mechanical advance with no retardation. 10 BTDC at cramnking speed. ~12 BTDC at idle, ~20 BTDC at 1500 rpm and ~30 BTDC at 3000 RPM. Retardation only subtracts the way I see it.