Old iron distributor vs. new alu one

[TheEngineer]

I am playing with distributors: Bosch P/N 0 231 185 009 (MB P/N 002 158 38 01) was in the vehicle and I found that I could not obtain 30º advance at 3000 rpm and 3ºATDC at idle because the vacuum retard could only move about 12º. It is limited by a fixed stop and I would have to file the stop to obtain more travel.
Bosch P/N 0 231 116 051 is the old iron distributor which is NLA and has been superseded by the aluminum one shown above. However, the vacuum actuated travel can be adjusted and it was therefore possible to obtain the ignition timing values per the book. The car appears to run better for it.
What is the opinion of the Pagoda experts about using one or the other distributors?

1969 280SL,Signal Red, A/T, P/S, A/C, Both tops, 3.27 axle. Retired engr. West Seattle, WA

[hands_aus]

Wasn't the Bosch 051 the original distributor installed in the car?

If that is the case, then certainly there would be no problems in replacing the later distributor with an 051 that is in good condition.
It seems to be appropriate to have the adjustable vacuum advance unit.

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[George Davis]

One bit of experience is that ignition timing at idle can affect your ability to set the idle air/fuel mix.  More advance speeds up the idle, which means you have to reduce the air and fuel to get proper idle speed, which seems to get the fi pump adjustment into a funny place where it doesn't behave properly.  Even at 3 degrees my pump adjustment becomes non-responsive.  I backed idle timing down 1 degree to solve this, using the vacuum adjustment on the 051 distributor.

From what I've read, the alu 009 distributor is closest to the US-spec '70/'71 distributor, which makes it not right for everything else.  My suggestion is stick with the 051, and if it needs a rebuild, sent it to Dan Caron (Benz Dr.).

George Davis
'69 280 SL Euro manual

[knirk]

I fully agree with George. I had the alu distributor in my 69 as well - and it gave me all kinds of problems when trying to match the settings for the idle and 3000 rpm. Take a look at this old string.

http://www.sl113.com/forums/index.php?topic=1455

I solved the problem by getting a rebuilt 051 distributor from Cees.

Per G. Birkeland
69 280 sl aut 834
Norway

[Bob G]

Can Dan Calton or Dr. Benz please email me. I have a question about my distributor.
Bob Geco
bobgeco@cs.com
1968 280SL

[Benz Dr.]

Just ask anyone who has been through this sort of thing and they'll tel you how much better the car performs with the proper equipment. Matching everything up is the key here. Right distributor working right, good set of wires, hot coil and everything timed right.

What some may not realise is that the distributor timing relates to the IP timing and the amount of fuel that the pump puts out. The pump timing is static but the distributor isn't. Increasing fuel delivery ( amount ) needs advancing ignition to get max performance. At least that's my theory.

Daniel G Caron

[A Dalton]

<<The pump timing is static but the distributor isn't. Increasing fuel delivery ( amount ) needs advancing ignition to get max performance. At least that's my theory...>

 If I can add to that:
The importance of setting these mechanical FI systems to factory specs is that there is no feed-back between the ignition and pump, as there is no feedback from the air to the fuel amounts. [ aside from vac link ]
 These are all predetermined in the measured design of the mechanicaly linked parts...kinda lile an old type-writer, if you will.
 So, the engineering design has set these measured specs to result in the best power/performance band, overall.
 Now, if each car was identical, driven the same , used the same gas, etc, they would not even need any adjusters.. but there are variables, so we can adjust all of these inter-related parts .
 SO , because the design has this spec. BASE LINE , setting everything up to spec  will give each car the best over-all performance. Any further tweaking should only be done after specs are set. Otherwise , you may have a setting way out of wack and still think your car is running well, but then when you go to a different load/rpm range , you get poor perfomance, etc.
 Although it is nice that we are now able to bring systems on these up to date technically [ like point conversion for ignition],there is no way to couple the fuel mix and ignition as the new cars do so well. [closed loop/exhaust 02 sensed]. So our mechanics/measures have to be right on the money and in perfect working order.
 It still is amazing how a little tweak on these can make such a difference...

 

[Benz Dr.]

Hey , that's pretty good.

 You're hired...........

Daniel G Caron

[rwmastel]

quote:Originally posted by George Davis

...... My suggestion is stick with the 051, and if it needs a rebuild, sent it to Dan Caron (Benz Dr.).

George, Dan, and other "Ingition Experienced Individuals",

How does one know when their distributor needs rebuilt?  Is there some imperical measurement or test?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Naj ✝︎]

theengineer,
When you set the timing to 30 degrees btdc @3000 rpm (without vacuum), what readings do you get at say 1500 rpm and at idle - still without vacuum?

naj

65 230SL
68 280SL

[TheEngineer]

To NAJ:
Now you ask, since I have the hood back on. It's really hard to see well because the hood is so much in the way. To give you good data, I'll connect a vacuum gauge, but not today. As I remember, the vacuum collapses as soon as I open the throttle. With no vacuum connected, I read about 14°BTDC. I don't remember at 1500 RPM, but it must have been per the BBB, otherwise I would have tinkered with it. I increased the travel of the vacuum diagphram about 2mm. This resulted in additional retard of about 4°. The 30° at 3,000 RPM did not change. The settings are now per the book and the car seems to run fine, but I haven't had it up to a prolonged 80MPH, that's as fast I can drive here

1969 280SL,Signal Red, A/T, P/S, A/C, Both tops, 3.27 axle. Retired engr. West Seattle, WA

[Benz Dr.]

How do I know thee oh worn distributor? Let me count the ways.....

 One of the ways is to do the idle test.
 Warm the engine fully with a short drive and then let it idle. Blip the throttle a few times and see if the idle speed changes. Throttle up to a bout 1,500 and then slowly release the throttle.
If the idle speed goes back to roughly the same amount every time the flyweight springs are in good shape. If it's all over the place you have weak springs or a lot of sticky goo on the advance plate. To test further run the engine at idle and then shut the ignition off. Wihout touching anything, restart the engine and see what the idle speed is. If it's a lot lower do this test several times. If the engine now runs at the same idle speed every time try increasing idle speed to 1,500 again and then release throttle. If it idles higher than the '' set '' speed you have worn springs or possible binding linckage.
The spings will usually pull the flyweights back when you stop the engine - something that can't happen while running if they're too weak.

Remove the cap and push on the rotor. It should move sideways smoothly and always return to the same position. If you can move it back more it may be sticking. Sometimes the drive at the end of the distributor will have some play but this is a different problem and one that shouldn't affect how the car runs too much. Make sure the small spring is installed bewtween the drive gear and the drive collar on the bootom of the distributor. You can tell it's installed because the whole distributor will spring up as you remove it from the housing it sits in.  This spring is important as it keeps a certain amount of tension between the drive collar and the drive gear.

Try to move the shaft where the rotor sits. It should feel tight with minimal amount of side play. Lifting the shaft up or down should be possible but it should be only a small amount ( maybe 1/8'' or so ) Sometimes the cam will be worn on the main shaft and will need replacement. This is rare but I've seen this and times where the whole thing was completely siezed up. This is most common on cars with CD ignition - less need need for tune ups leads to less maintenance.

In short I haven't seen where ANY distributor couldn't benifit rom a good cleaning and set up. It's rare that I find nothing wrong at all.

I've had number of people ask me about costs so if it's Ok with everyone I'll talk about that now.

The rebuild kits are about $40.00 and it takes 3 - 4 hours to go through and adverage rebuild. This includes complete dissasembly and inpection of all parts. The housing is glass beaded and painted on cast iron models. All new parts are installed unless the bearings are in good shape - everything else is replaced. I install new points and condensor.
Once it's partly assembled I run it on my distributor tester and check for function using a mighty vac to test the advance system. Any djustments are made before final assembly.
After I have it working right I finish assembly and then run it up to 6,000 RPM or higher. The best ones will go to 7,000 before the points start to float. This is an indication of how tight the bearings and other moving pieces are inside of the distributor. I have graphs which tell me what the advance curves are so I know if I have it set properly.

Total costs are a standard $189.00 USD. Any other needed parts would be extra of course. I'm hoping to have a supply of rebuilt units on hand for quicker turn around but most of the time I can have one in and out in a day or two.

Daniel G Caron

[A Dalton]

D.C.
 Do you sell dist individual parts?
Tnx
A Dalton

[Benz Dr.]

Only time you will need extra parts is if the main shaft is worn, the vacuum cell is broken or the cam is worn. Almost all the other small parts you would need come in the rebuild kit.
I have several parted out distributors that I use as long as the parts are the same. These cars use 3 different types of distributor, vaccum advance, vacuum retard and the later aluminum ones. The sedans use similar units so parts can be mixed and matched.

Daniel G Caron

[TheEngineer]

Dear Dr. Benz:
It is exceedingly rare to find such good instructions presented so well. I have saved your thesis in my file entitled:"Operation Linke Spur".
Thank you very much.

1969 280SL,Signal Red, A/T, P/S, A/C, Both tops, 3.27 axle. Retired engr. West Seattle, WA

[Ben]

I have my 051 set for 30deg at 3000RPM which seems to give me roughly 4 or 5 deg at idle........is this correct ?

I thought I had something going bad in the dizzie as the car was doing a lot of bucking at very slow speeds. I had decided to change the lenght of the vacuum rod, the vacuum unit needs to come off right ?

Anyway I discovered that the rod at the fuel pump was not set right, and a small adjustment here has transformed the low speed response, it will lug from about 900RPM in top with no jerkiness at all !

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[George Davis]

A couple of thoughts:

I used a vernier caliper to measure side play in my distributor shaft.  The measurement was a bit rough, but showed at least 0.004 inch play.  I think the factory spec is 0.002, max.  The car actually ran ok, but it burned up points in short order.  After a rebuild by Dan, the points are lasting a lot longer.  Note that electronic ignition conversions can hide this sort of wear.

Did you note something Dan said about cars with CD ignitions having seized shafts due to lack of maintenance?  As far as I'm concerned, that is one of the best arguments for staying with points.  Points force you to do distributor maintenance, which includes oiling the shaft (under the rotor and the little oiler on the side).  Very easy to ignore that if you never need to change points.

Ben, I believe the factory spec is 3 degrees ATDC at idle with vacuum connected.  I removed the vacuum capsule to adjust it, it's easiest with the entire distributor out.  (Yes, Dan had set it spot on at 3 degrees, but I wanted 2 degrees).  You'll probably have to readjust the idle air and fuel if you change the advance at idle.



George Davis
'69 280 SL Euro manual

[Benz Dr.]

The CD ignition units I talk about are the factory installed ones from mid '69 until end of production. These were also used in 250 ( 114 ) and 280S ( M 130 ) until about 1972. Early 450SL's often have seized mechanical advance.

Daniel G Caron

[Ben]

quote:Ben, I believe the factory spec is 3 degrees ATDC at idle with vacuum connected. I removed the vacuum capsule to adjust it, it's easiest with the entire distributor out. (Yes, Dan had set it spot on at 3 degrees, but I wanted 2 degrees). You'll probably have to readjust the idle air and fuel if you change the advance at idle

........is that for my '051 equipped 230 ??

If so I'll readjust just to see if things improve...........though its running and idling great right now !

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[George Davis]

Ben,

according to the Tabellenbuch, all 230, 250, and 280 SL's equipped with the 051 distributor have the following specs:

Idle:  2 +/-1 degrees ATDC, with vacuum
1500 rpm: 12-19 degrees BTDC, without vacuum
3000 rpm: 30 degrees BTDC, without vacuum
4500 rpm: 30 degrees BTDC, without vacuum
All measurements made with no load on the engine.

Please let us know if readjusting the idle timing makes any difference.

George Davis
'69 280 SL Euro manual

[Benz Dr.]

051 distributors have 10 degrees of vacuum movement and 20 degrees of mechanical movement on average. I set them so that they move a total of 30 degrees by fine tunning the vacuum pull rod - the mechanical portion has a pre set limit.
You pretty much have to run these engines at slightly ADTC or they tend to ping. To get 30 degrees at 3,000 RPM the vacuum portion would need 6 degrees of movement on the tester I use ( I have to doubble everything because the distributor turns at 1/2 engine RPM )if you want to run at 2 degrees ATDC.

Daniel G Caron

[A Dalton]

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7928055925&category=33690

[hands_aus]

Hello George,

What version of the workshop manual are you referencing and what job number is it?
I have a manual for cars starting 1959 and I would like to be sure the info matches.
thanks

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[rwmastel]

quote:Originally posted by hands_aus

Hello George,

What version of the workshop manual are you referencing and what job number is it?
I have a manual for cars starting 1959 and I would like to be sure the info matches.
thanks

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

Bob,
George can correct me if I'm wrong, but I think the "Tabellenbuch" is the Technical Data Book.  It supplies charts of info regarding fluid capacities, torque specifications, and other measurements.  Not a shop manual, but a reference manual.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[hands_aus]

Hey Rodd,
Thanks for that info.
I asked because my Service manual 1959- (BBB) says that the timing should be 2 + 2 ATDC at idle, with vacuum and no load. It states because it is a retard system there should be NO vacuum at idle and as such the timing should be adjusted only at IDLE.

I must admit the info difference provides small variances but they could translate into performance problems in the car.

These books should have the same info, given they are produced by MB.
regards

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto