timing questiond

[jim 56]

hello I could use some help with the timing of my 1972 M130 engine with automatic tranny and a/c.the serial # on the engine is 30 980 12 066875 I think it is the newer engine.It has the transistor ignition
1)the distributor is aluminum 0231 116 068 j1u6 is this a vacuum advance or retard dist.
2)what should I time the engine at at idle, books are very confusing
3)should I time it with the vacuum to the distributor on or off
Thank You

[Aaron h]

-The engine number should read 130.980-12-066875. 
-Transistorized ignitions and aluminum distributors were present starting in 1969.
-Automatic and with or without air conditioning have no affect on ignition timing settings at the distributor.
-Ignition "retard" is only cancellation of ignition advance.  The timing isn't actually retarded.  Whether or not this engine has this will depend on if it and the
 distributor are a European or a U.S. version.  If your SL has the black RPM and change over switch, then it'll have the advance cancellation.
-Ignition timing at idle (800RPM) is set WITH vacuum connected to 6° a. TDC.
-Ignition advance should be 32°-36° at 3,000 RPM with vacuum connected.  At 4,500 RPM it should be 36°-40°.
-Ignition timing at starter speed (without vacuum) should be 14° b. TDC.   
-All of the above is assuming that you have a U.S. version engine.

[Berggreen]

-All of the above is assuming that you have a U.S. version engine.

....and the US relays and vacuum drives for the distributor actually works! They usuallly do not work, and are expensive to fix. Furthermore, they did nothing good for the performance of the car, as they were only introduced by MB to accommodate stricter US emission control regulations in the late 1960’es.

The European configuration with a 051 distributor and a European throttle house sourching vacuum from under the throttle body is a much better ignition configuration. So if you can get your hands on such a set then go for that.

Alternatively, instead of the 051 distributor, which may also be tired and worn out, you can go for a modern digital 123ignition distributor, which also rules out wear on the old BOSCH distributors, because you replace the entire unit and thus get rid of the old distributor parts. You can in this case reuse the US throttle house with a vacuum port on the side of the body, but you then need to get the programmable version of the 123ignition, and use Mike’s special maps. Otherwise, some of the US throttle bodies already have an unused vacuum port at the bottom of the body, but you need to check if the port has been drilled all the way through. Otherwise, find a European throttle body on EBay and install instead, and then you can use the standard 123ignition in program 8. Last time I looked there were several European throttle bodies for sale for around 2-300 EUR.

I have replaced the US ignition systems and throttle bodies on both my 280SLs with standard 123ignition distributors running them in program 8, and it works GREAT. You have a world of difference to the tired old BOSCH US systems, and furthermore you can now forget about changing points and condensations.

Hope this helps and good luck!

Christian

[Dave H]

Hi Christian
I have a 280 with euro throttle, no emissions equipment and a 123-6RV on program 8.
With vacuum pipe connected and checking with a strobe light Im at 8 degrees BTDC idle and 38 BTDC at 3000 rpm? is this correct ?

[Benz Dr.]

Hi Christian
I have a 280 with euro throttle, no emissions equipment and a 123-6RV on program 8.
With vacuum pipe connected and checking with a strobe light Im at 8 degrees BTDC idle and 38 BTDC at 3000 rpm? is this correct ?

That should work very well.

[Berggreen]

That should work very well.

Agree! Sounds right. So if you still have problems, then I doubt they are ignition related.

How is the car running with this setup?

Cheers,

Christian 

[Dave H]

Not too good, judging by the split linkage test and state of the plugs it’s running way too rich and I can’t lean it.
It’s a brand new fuel pump and the injectors are all good, plugs are B5s.
Barometrics  good and even with no shims it’s still rich.
Idle and full range adjusters are at their  limit and it’s still rich.
Only thing I can think is that the WRD plunger is not leaning it out but I doubt this.
Other thing is when Warm WRD is still drawing some air in and if I block it with my thumb it stalls, should it close off completely.
I have no history with this pump and it’s off a 250 ,when I bought the car it ran badly.
Im tempted to get a 24Y and have it rebuilt.

[Benz Dr.]

Not too good, judging by the split linkage test and state of the plugs it’s running way too rich and I can’t lean it.
It’s a brand new fuel pump and the injectors are all good, plugs are B5s.
Barometrics  good and even with no shims it’s still rich.
Idle and full range adjusters are at their  limit and it’s still rich.
Only thing I can think is that the WRD plunger is not leaning it out but I doubt this.
Other thing is when Warm WRD is still drawing some air in and if I block it with my thumb it stalls, should it close off completely.
I have no history with this pump and it’s off a 250 ,when I bought the car it ran badly.
Im tempted to get a 24Y and have it rebuilt.

Better look more closely at the warm running device. If you can stall the engine it's not shutting off and that's where the extra fuel is coming from. I would also check the cold start valve. They can add a lot of extra fuel if they're leaking.

If you have the wrong pump on your engine it will never run right.

[Peter]

Not too good, judging by the split linkage test and state of the plugs it’s running way too rich and I can’t lean it.
........

maybe the adjustment after all. Below the information from "Haynes" and 123 regarding the ignition setting. This is not 8 BTDC at idling.

[Berggreen]

maybe the adjustment after all. Below the information from "Haynes" and 123 regarding the ignition setting. This is not 8 BTDC at idling.

I think this is timing settings for the US 280SL with the emission control system active, where they push the timing advance back to ADTC in idle to reduce emissions. But this is not doing anything good for performance of the engine, and this is only done like this by MB to comply with the US authority demands back then, so that they could continue selling the 280SL in the USA. Many other European car companies just gave up selling their cars and pulled out of the US market, because these demands made it impossible to sell their cars in the USA.

So generally in my view, the US-spec 280SL is crap compared to the European counterpart. The US spec 280SL was never a good car, and today it should be converted to the European specs to take full advantage of the engine performance. But that is just my 2 cents! 

Cheers,

Christian 

[Berggreen]

Im tempted to get a 24Y and have it rebuilt.

If you have a M129, I don't think a R24Y pump will fit the engine, as this was a special pump type for the US-spec 280SL. The European 280SL's used either a R23 or R25 pump, which I think is superior to the R24Y.

I unfortunately have a R24Y on both my 280SLs, and if they are to be exchanged at some point, I would definately try to get a R25 or R23, if I at that time can get my hands on a European pump.

Check the manual. There is a table with all the pump types and what fitted on which engines.

And I agree with the above statements. Looks like either the WRD or the cold start valve could be the source of the extra fuel, which is enriching your mixture - not the pump, if you have removed all the shims under the barometric compensator. I think most have 2-3 mm shims, so no shims sounds like you are enriching the mixture from another source. Also, prepare to add more shims, once you find the external fuel source, because otherwise you most likely will run much too lean with no shims under the compensator.....

Cheers,

Christian 

[Peter]

I think this is timing settings for the US 280SL with the emission control system active, where they push the timing advance back to ADTC in idle to reduce emissions.............

Not really.
Haynes information shows following about USA ignition.

[Berggreen]

Not really.
Haynes information shows following about USA ignition.

I have difficulties seeing how you can ever make a 280SL run decent with so bad timing adjustments. You have to reach around 35-38 degrees at 3000 RPM; and that will not be possible, if you push the timing advance back to ADTC in idle. The distributor only have so much advance it can deliver, and it will not make the 35-38 degrees with ADTC timing at idle.

But maybe I am wrong.....but I have both my 280SL at 8 degrees BDTC at idle to be able to reach the 38 degree mark at 3000 RPM.

Cheers,

Christian

[Peter]

Maybe you are right, but also the BBB is in line with Haynes.

[Benz Dr.]

I have difficulties seeing how you can ever make a 280SL run decent with so bad timing adjustments. You have to reach around 35-38 degrees at 3000 RPM; and that will not be possible, if you push the timing advance back to ADTC in idle. The distributor only have so much advance it can deliver, and it will not make the 35-38 degrees with ADTC timing at idle.

But maybe I am wrong.....but I have both my 280SL at 8 degrees BDTC at idle to be able to reach the 38 degree mark at 3000 RPM.

Cheers,

Christian

For the early 280SL and Euro verson,  8 degrees BTDC is what you should have. The late USA version has a special distributor that has 22 degrees of advance which allows timing to go ATDC and still advance to 38 degrees BTDC at 3,000 RPM. 

[Berggreen]

For the early 280SL and Euro verson,  8 degrees BTDC is what you should have. The late USA version has a special distributor that has 22 degrees of advance which allows timing to go ATDC and still advance to 38 degrees BTDC at 3,000 RPM.

Yes, exactly, the BOSCH 062 distributor was used on the US-spec 280SL with emission control.

But if the ignition today is converted to a 123ignition or a BOSCH 051 (like on the original Euro-spec 280SL), and the emission control system is disengaged, then I would as you also write, set the timing to 8 degrees BDTC at idle and go for program 8 (Euro spec 280SL), if converting to a standard 123.

I am convinced this is how you get the most performance out of your 280SL, if it is an original US-spec 280SL - which most 280SLs actually are, both in the US and here in Europe as well, because so many US-spec 280SLs have been re-imported back to Europe. Remember that most new w113s were exported to the US, so an original Euro-spec 280SL is actually a rare bird, as it was a very expensive car back then here in Europe, and only the very few could afford it.

As some examples, here in Denmark the approximate prices were in 1969-1970:
MB 280SL: 150.000 DKK
Volvo 1800S: 55.000 DKK
Volvo 121 Amazon: 25.000 DKK
VW Beetle: 12.000 DKK

So this puts things in perspective, and why so few w113s were sold here in Europe.

A contributing factor was probably also that a convertible is less practical in Northern Europe (due to the weather), where most of the wealth were located, compared to Southern Europe where a convertible makes more sense as a daily driver, but where even fewer were able to pay so much for a car like the w113 back in the late ‘60es and early ‘70es.

Cheers,

Christian

[Peter]

Hi Christian,

I did some testing today.
Using 123/MERCEDES-6-R-V at position 8 (replacing Bosch 051), euro throttle with vacuum.

Is your 8 degrees BDTC with or without vacuum hose connected?

My finding:
8 degrees BDTC without vacuum hose connected = 2 degrees ADTC with vacuum hose connected.

[Berggreen]

Hi Christian,

I did some testing today.
Using 123/MERCEDES-6-R-V at position 8 (replacing Bosch 051), euro throttle with vacuum.

Is your 8 degrees BDTC with or without vacuum hose connected?

My finding:
8 degrees BDTC without vacuum hose connected = 2 degrees ADTC with vacuum hose connected.

Hi Peter

I have 8 degrees BDTC with vacuum connected.

I think that with your euro-spec ignition system, you are too low in advance at idle. Have you checked what degrees you have a 3000 RPM?

I initially also trusted the MB service manual, where the 3 degrees ADTC (with vacuum) is stated - and surprisingly for the euro-spec 280SL (see below). For the US spec 280SL they recommend 8 degrees ADTC, see also below.

But reading and listening to people and their experiences here on the forum, I eventually went along with what is the general recommendation of 8 degrees BDTC with vacuum, because this is what works for the euro-spec ignition settings.

Cheers,

Christian

Ps.: One explanation for the 3 degrees ADTC for the euro-spec 280SL could be, that around 1970 some European countries also started to introduce some demands to exhaust emissions, though probably not as strict as in the US at that time. Pushing the ignition timing to ADTC in idle is actually a way of reducing emissions in the rpm range where they are measured, but at the cost of performance. So I am guessing this was a way to get the late 280SLs passed the inspections without too much extra effort as the R107 was soon going to take over, and then people tuned the ignition timing up again on their 280SLs to regain the performance of the engine - at least this is what we prefer to do today. 

[Peter]

Thanks Christian,

So it’s own/forum experience the 8 degrees BTDC with vacuum.

I was always afraid for the engine by being so far out of the original ignition specification, but I’m going to test the 8 degrees BTDC with vacuum to see how the car runs.

[Berggreen]

Thanks Christian,

So it’s own/forum experience the 8 degrees BTDC with vacuum.

I was always afraid for the engine by being so far out of the original ignition specification, but I’m going to test the 8 degrees BTDC with vacuum to see how the car runs.

You are welcome, and yes from experience, and I guess also from the early pre-emission control 280SLs, as well as 250SL and 230SL, for which I think MB stated 8 degrees BTDC with vacuum.

But I am sure others know more about this than me.

[Pawel66]

I have this setting too. Try it.

[Benz Dr.]

There are a number of different ways you can get to 38 degrees at 3,000 RPM but that's the magic number to look for.

[Peter]

Hi Christian, Herr Dr. Benz, Pawel, I did some test-drives today and I have to say, 8 degrees BTDC with vacuum - Bosch 051 - Euro throttle and 123, it is actually much better, it is great! A hug improvement.   

Hopefully there is no downside like burned or overheated valves?

[Berggreen]

Hi Christian, Herr Dr. Benz, Pawel, I did some test-drives today and I have to say, 8 degrees BTDC with vacuum - Bosch 051 - Euro throttle and 123, it is actually much better, it is great! A hug improvement.   

Hopefully there is no downside like burned or overheated valves?

Hi Peter

Happy to hear that! 😊

Watch your spark plugs and the color they have, if you are worried about running too hot and burning valves. If too white then richen the fuel mixture, eg. by adding more shims under your barometric compensator.

I am tuning my two 280SLs in at the moment and are watching my spark plugs closely/often, and I have richened the fuel mixture several times as the plugs were too white, and I was running too lean.

They are running better and better the closer I get to the sweet spot. It is incredible how much a 0.1 or 0.2 mm shim makes a difference !

Cheers,

Christian 😎

[Peter]

Watch your spark plugs and the color they have, if you are worried about running too hot and burning valves. If too white then richen the fuel mixture, eg. by adding more shims under your barometric compensator.

Hi Christian,

Thanks for advice, interesting!
Adding more shims under the barometric compensator will also influence the CO level of the idle speed adjustment which should be between 3,5/4,5%.  Do you have experience what the level than should be?

Thanks, Peter

[Pawel66]

You then re-adjust the idle again to specs.

[Berggreen]

Hi Christian,

Thanks for advice, interesting!
Adding more shims under the barometric compensator will also influence the CO level of the idle speed adjustment which should be between 3,5/4,5%.  Do you have experience what the level than should be?

Thanks, Peter

Hi Peter

Yes and CO% 3.5-4.5 if possible, and it does not go out at the end of the warm runnnng program. If it does, I give it a bit richer mixture at idle with the idle mixture screw.

I think the most important is that the mixture is correct in the mid and high rpm range. And this can only be checked by watching the spark plug color, unless you have access to a dyno-field, where you can measure the CO under load.

Also watch out for pinging, indicating a too high advance. But it should’nt be, if you have 8 degrees BDTC at idle (800 RPM).

Cheers,

Christian

[Peter]

Thanks Gents,

I'm going to take a close look at the spark plugs and fuel mixture as it is not the intention to damage the engine.