Ignition and distributor

[knirk]

Hello
As I have previously written my engine problem has been lack of throttle response after it’s warm. Naj suggested to look at the ignition – which I did.

The distributor number is 0 231 185 010 JFU6 and is an electronic system. The number is not on the BBB list as correct for any of the engine types. Previously setting was 30 BTDC at 3000 rpm. With this setting the idle showed 14 ATDC (book says 2-4 ATDC) w/vacuum and 11 BTDC wo/vacuum. The retard is then 25 (book 8-14).

I then adjusted the ignition “by ear”, and the engine response improved a lot and is now very good. I had to click back about 10 notches on the FI to get the idle to 800 again. I am now back to the pre-overhaul FI setting. So everything seems nice.

But when I checked the ignition with the strobe light the reading were: 50 BTDC at 3000 / 40 BTDC at 1500 and 8 BTDC at idle. This is way off everything and I am beginning to suspect my stobe light. If this is correct would the engine run so nicely without backfires and pinging?

There is no names on the electronic ignition – anybody out there recognize it?


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Download Attachment: ignition.jpg
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Per G. Birkeland
69 280 sl aut 834
Norway

[Naj ✝︎]

Per,
That trigger mech. in the distributor looks like Crane. The latest boxes are black but I believe Crane were previously Allison??
The alli body of the distributor suggests its from a late car but I don't know which.
On the old distributors, you could adjust the retard value by adjusting the length of the rod on the vacuum unit, but yours looks like a fixed length.
Not much help is it? :x
naj

65 230SL
68 280SL

[Naj ✝︎]

C'mon now guys,
Somebody dive in here and explain (to me like I'm a four year old  :oops: ) why we need to retard the timing at idling?
naj

65 230SL
68 280SL

[George Davis]

Per,

looks like an Allison/Crane system to me, too.  If I had your distributor, I'd replace it as soon as possible with the correct one.  With that much ignition advance you run the risk of damaging the engine when it's operated under load.  Under light load it may run pretty well, but under heavier load the early ignition of the mixture will raise the temperature in the combustion chamber which can lead to detonation or preignition.

Naj,

here's a guess on why the ignition is retarded at idle.  The flame propagation rate of a quiescent air/fuel mixture is fairly constant, but it's much faster in a swirling, turbulent mixture.  These engines appear to have a large "squish" area where the top of the piston comes close to the flat surface of the head.  The mixture is squished out at TDC, resulting in a lot of swirling and turbulence in the combustion chamber.  Coupled with the fine atomization of the injection system, my guess is that the flame propagation rate is very high.  The faster the flame propagates, the less advance is needed.  There, that's my silliness for the day; anyone else?

George Davis
'69 280 SL Euro manual

[knirk]

Agree George,
I guess my distributor is usable as long as I make sure my timing light is correct and keep it at 30/3000.

Now I am looking for a 051 distributor - anybody have one for sale?

Hopfully I can get my electronic part from my freek distributor to fit in a 051.

Per G. Birkeland
69 280 sl aut 834
Norway

[knirk]

I now have a usable distributor.

I made a 4mm treaded hole in the side of the distributor and mounted a 4mm screw with a lock nut. I was then able to adjust directly on the upper plate the amount of retard by adjusting this screw. It worked perfectly and I am back to normal ignition settings and the idle backfire stopped.

I would like everything original so I am still looking for the 051 distributor if anybody have one laying around.

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Per G. Birkeland
69 280 sl aut 834
Norway

[Cees Klumper]

Very creative Per! Although I appreciate this being far from original you would like to have the proper set-up. I do have an extra 051 distributor. Email me offline please for getting this sorted out.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[blairwag]

Per,
What model/year is your car?  I have the "0 231 185 010" distributor in my 1971 208SL, and have been assured that this is the correct replacement for the engine/car. I'm preparing, as I type, to pruchase all I need to upgrade to the Crane XR700 - which appears to be installed in your machine as well. I was feeling pretty confident, until reading this thread.
All,
Why is the "0 231 185 010" not right?  What makes the 051 correct?  Do I have reason to worry?  I can't afford to toss $$$ away purchasing the wrong stuff.


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[George Davis]

Per,

I agree with Cees, very creative and clever solution!

Blair,

I think the 0 231 185 010 is the only available factory replacement distributor, and in your case it's probably ok.  The original distributor for a '70/'71 US-spec 280 SL is the 0 231 116 062 distributor, but the 010 appears to have similar specs (for the vacuum retard, at least).  According to Per's post, the 010 has about 25 degrees of vacuum retard, whereas the spec for the 062 is 17-23 degrees vacuum retard.
Timing specs for the '70/'71 US cars with the 062 are 8 degrees ATDC at idle; 0-5 BTDC at 1500 rpm; and 25-30 BTDC at 3000 rpm... all with vacuum connected.
European 280 SLs appear to all use the 051 distributor, which only has about 8-10 degrees of vacuum retard.

George Davis
'69 280 SL Euro manual

[knirk]

William,

I have a 1969 280 US and should have had the 051 distributor.

I think George comments are correct. MB needed a new distributor with larger vacuum retard for the increased emission control demands in 1970 and 71. This was the 0 231 116 062. From earlier posts I can see that several members with 70/71 sl’s have the 0 231 185 010. It may be the same distributor with just a new part number for the later reproduction.

I am beginning to think that the only difference between 051 and 062/010 is the vacuum advance unit. The 051 has an adjustable arm to adjust the retard. The 062/010 has a fixed length  arm that cannot be adjusted unless you modify it like I did. Probably because the emission rules demanded such a solution.


Per G. Birkeland
69 280 sl aut 834
Norway

[Benz Dr.]

If you retard the ignition you have a burn which is slightly less clean and the back pressure in the exhaust system will help to lower the NOX readings. This is a fairly crude way to reduce emissions.
Vacuum retard is just a better system as far as control goes. You have maximum vacuum at idle so you can easily pull the distributor to the zero position. As soon as you throttle up the vacuum starts to go away and the distributor springs forward ( on the 051 )
 On vacuum advance units the vacuum has to pull the advance forward and this doesn't always work properly, especially if you have any leaks in the system.
The 062 unit has vacuum going to it at all times and a speed relay switches a valve that shuts the vacuum off above 2,500 RPM. This makes the distributor advance all at once and the vacuum portion takes over from the mechanical advance part of the distributor just as it starts to end. The transition is fairly smooth but you can tell if it's not working because the engine will lack mid range power.

regards,
Dan Caron
 SL Barn


Daniel G Caron

[erickmarciano]

my late 280sl from europe has a 051 stock

1971 280sl
1962 VW
1954 Allstate vespa
1958 gs150 vespa
1962 gs160 vespa

[knirk]

Eric,
Then you have the correct one. It's only US 1970 and 1971 280 sl’s that use the other type.


Per G. Birkeland
69 280 sl aut 834
Norway

[blairwag]

Per,
Did you ever solve this initial mystery:
"...ignition with the strobe light the reading were: 50 BTDC at 3000 / 40 BTDC at 1500 and 8 BTDC at idle. This is way off..."

My car operates with virtually the EXACT same timing, using my timing light. My light is good! *AND* it did NOT have the transistorized module - that had been bypassed in favor of a standard kettering ignition system long ago.

Tonight I try to start it for the first time with the Crane XR700, and hope NOT to set toe timing to the correct BBB values. What was your fix?

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[jeffc280sl]

Hello Per,
If you have the later emission system I suggest you look at the operation of the speed relay.  It is part of the emission system in the US and it is supposed to remove vacumm retard on the distributor at 2400 RPMs and re-apply vacumm at 2200 RPMs via the two way valve.  Mine was broken as were two used relays I picked up along the way.  If it is not operating properly it could account for some timing variance from spec at higher revs.  I suggested to someone else that you take a 12 V lamp with about 6 feet of wire and insert the open end of the wire into the connector on the two way valve.  Push the connector with wires back on the valve and place the bulb just outside the hood so that you can see it while driving.  At 2400 RPMs the bulb should turn on.  If it doesn't you nay have a defective relay.  I have intslled an after market digital relay whic performs the same task and it works great.  Let me know if yours works.



Jeff C.
1970 280SL 4-speed

[jeffc280sl]

Per,

By the way, I have the same electronic ignition system and distributor in my 1970 280SL 4 speed

Jeff C.
1970 280SL 4-speed

[knirk]

William,
The problem with my timing numbers came from my wrong type distributor. When I set it “by ear”, what I did was advancing the timing from 14 ATDC to 8 BTDC (shown afterwards by the strobe). At this setting the engine ran very well, but this also gave me 50 at 3000rpm which couldn’t be healthy. Then I found out that I had a wrong distributor with 25 retard (i.s.o. 8-14) and made the modification to be able to adjust the retard. I went back to 30/3000 and adjusted the retard at idle to about 4 ATDC. The idle rpm increased to about 1200 so several IP click backs were necessary to get down to 800rpm. Now the engine runs fine. I still have a lack of throttle response, but I think this is the famous Control Valve/Heat Sensor again. I will be back tomorrow with a new string.

Cees sold me a 051 distributor, and when I get this I expect to be back on track, at least with the ignition problems.


Per G. Birkeland
69 280 sl aut 834
Norway

[knirk]

Jeff
Do you know the exact type of your system? I understand that mine is a Crane, but not what type number it is. Did the 1970/71 sl’s come with electronic ignition as standard?

Per G. Birkeland
69 280 sl aut 834
Norway

[jeffc280sl]

Per,

I have the Crane XR700 ignition system and a lot of documentation.  I know the 70 and 71 SLs came with a   transistorized ignition system as a standard which was mounted under the battery tray.  Let me know if you need documentation.

Jeff C.
1970 280SL 4-speed

[knirk]

Thanks Jeff,

Then I can assume that I also have the Crane XR700, and then I have the correct documentation already. Bob Smith sent me some very useful PDF files.


Per G. Birkeland
69 280 sl aut 834
Norway