Old iron distributor vs. new alu one

[A Dalton]

Bisbane Bob,

 I have the Service Manual starting Aug of 1959 .
 Mine states the same specs [ 2+2 ATDC at idle with vac, no load]
 so, this may be the same book...

 This equates to 2 to 4 degrees ATDC with vac retard.
 You have to have vac at idle for the vac element to bring it to retarded ATDC . So, the throttle has to be completely closed [ full vac.] Once the throttle is opened , vac collapses and ignition immediately goes advanced .  A quick test for the system is to pull the dist. vac line while at idle. This allows NO vac to the distributor and the timing advances due to NO retard, so you should  see the RPMs immediately increase.  That verifies the vac diaphragm  is doing its job.
 
 The timing at 30 degrees is set first and then you bring the retard into spec by adjusting the retard vac diaphragm rod length at idle, no load,full vac.
 The reason for doing  this is that the retard rod adjuster will not change the 30 degree setting ..it only changes the amount the retard will bring the timing into the ATDC range...
 I personally cheat a little on this low end timing and set it at TDC. I prefer a higher than spec idle as I have stick shifts and I like to run slightly rich...
 Does your book also have the # 4 and 5 footnotes on this ?
Tnx
Arthur

[Ben]

I have read those specs from that book and assumed that the idle was 2 deg ADTC +/- 2 degrees, therefore allowing a setting of anywhere between 0deg and 4deg ATDC........whichever delivers your required idle !!

I need to check mine again soon so I'd like if someone clarified this !

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

[Malc]

The picture of the distributor on Ebay (posted by A Dalton) is in "good working order" Note that the shaft into the drive is all rusty and the o-ring seal is missing.....
Or am I missing something here?

Note too that the distributor body is very, very similiar to the ones used by BMW (theres a surprise)
Malc

[hands_aus]

Hey Arthur,
Yes it is the same book and has all the notes.
Thanks for explaining the way to do correct timing adjustment.
I was just doing the timing at idle and set it at 4 degrees ATDC.
I didn't read it as 2 +/- 2 but as it says, 2 + 2, don't know why they didn't just say 4 degrees and be done with it. I suppose that is very specific where a range of 2-4 is more achieveable.

Arthur how do you adjust the vacuum rod in the distributor at idle if the distributor cap is on?
I thought it was done from the inside?

I can't go out and look because my car is in having the rear axle rubbers and bearings replaced. It will be back maybe next, just before the weekend.

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

[George Davis]

Bob et al.,

Rodd is correct, the "Tabellenbuch" is the Technical Data Book, 1969 edition.  The BBB I have gives the same specs, it's the 1971 edition, or thereabouts.

To adjust the vacuum rod, the distributor cap has to come off.  Someone who's done it few times might be able to make the adjustment with the distributor on the engine, but for me doing it the first and only time, taking the distributor off and taking the vacuum capsule off the distributor was easiest.  I think I turned the shaft 1 or 2 turns and got the 1 degree change I was looking for, but it might take a little trial and error.  Note/mark the distributor body orientation each time you pull it out so you can get it back more-or-less in the right position.



George Davis
'69 280 SL Euro manual

[Ben]

quote:Arthur how do you adjust the vacuum rod in the distributor at idle if the distributor cap is on?
I thought it was done from the inside?

........yeah I think you need switch the motor off and remove the actual vacuum unit from the dizzie and then adjust the rod. A bit trial and error by the sounds of it !


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

[A Dalton]

My understanding of 2 +2 ATDC  is that they allow anywhere from 2 ATDC to 4 ATDC.
 If they were to allow you +/- 2 from 2 ATDC , they would allow from zero [ TDC]  to 4 ATDC.

 Some of the vac retards have an outside port/screw to adjust the vac amount...

[Benz Dr.]

Remember how I said I set the distributor to give a combined total of 30 degrees? More vacuum  movement will equal more total movement since the two function seperately yet give a total amount.
Where you set the idle timing has everything to do with your total advance number. If you need more retard at idle and still want to maintain 30 degrees at 3,000 RPM, you will need to move the pull rod to compensate.
Which I think is what everyone is saying.

Daniel G Caron

[A Dalton]

<<<Which I think is what everyone is saying.>>

 Exactly..

 It is two systems [vac activated and centrifical weight/rpm activated]combined...
 So , at idle ,the weights have not started to move yet , but the engine vac is pulling the dist to full retard at  idle .
 So , the TOTAL advance is the degrees from total retard to total mechanical advance settings.
 The great thing about this retard system [ over a vac advance system], is the fact that as soon as one hits the throttle [opening the plate and collapsing the vac], the engine gets immediate advance.
  So, you can have a ATDC idle setting without lossing power at the lower rpm ranges.

 One of the reasons that it  is so important to have the throttle plate completely closed at idle, aside from the fact the the  FI pump requires this for setting idle a/f mix, is that the vac hose port is behind the throttle plate and that is when the vac to dist. is max.  If the throttle plate is not seating properly it not only effects the a/f mix, but also the amount of timing retard ...

[Benz Dr.]

That is basically correct.

The vacuum required to move the advance plate is less than you might think and it starts to move at around 5'' of vacuum. Most are on full by 11 to 13'' so the throttle plate can be opened a small amount and still work.( The average engine will produce at least 15'' or more at idle if everything is in good shape - some produce 19'' or more) The reason I say this is beacuse there are times where you won't get enough air into the engine with the air adjustment screw alone. This is a case of rich running and is not right but it's sometimes the only way to get any kind of an idle. The idle speed will likely be too high but at least the car will drive. You will be forced to open the throttle plate a bit to lean out the mixture and retard the timing to get the idle speed down. Not good but that's the quick choices.

The mechanical portion starts right at or near idle speed. This varies from unit to unit but most start together and the vacuum portion is graduated so it doesn't happen all at once. The mechanical takes longer to top out at around 2,500 RPM on most cars. Some distributors have two curves and another starts above 4,500 RPM ( 450 SL's have this ) These units have two different sized fly weights to give you two seperate curves. It's a combination of flyweight size and spring tension that gives you your advance curve - the springs time when it starts and the weights determine how fast they open ( the spring tension controls this as well to some degree )
Some cars have both vacuum advance and retard controlled by engine temps and other possible inputs. The distributor will advance when cold, retard when hot and advance again if too hot. All these things can be put into the system to deliver the maximum in performance and emission controls.
 
Just try to make it all work after 20 years of non function .......

Daniel G Caron

[A Dalton]

True..
 That is why it is so important to use a vac gauge when setting things up , specially a/f mix..

  side note that slightly pertains here ... if one does have a healthy engine capable of good vac, the air bleed screw should be quite capable of leaning out the idle to 3.5/4.5 at proper rpms without opening the plate..
[ assuming the screw port and lead-in hose are not plugged with crap, which I have seen]
 ... if this "can't lean out" w/bleed screw/ pump detent adjuster combo condition does come up, one  place to look is at the barometric compensator at the top of the pump.
 They wear with age and the pin then  protrudes less than spec, causing the entire range of the pump to be rich biased, no matter what you do.. pretty common complaint on 113s.  This is suspect when one turns the rear pump adjuster to the lean point of no longer feeling the detents/clicks of the screw... you are maxed and still rich..
 The compensator can be turned in to lean out the entire range out, but care is needed here not to go too far..
 If you adjust this correctly, you can then bring the rear fuel adjuster back to click status base line  and get the correct idle and CO with the bleed screw.
 This is tricky work and should be done  w/only slight adjustment at a time and preferably w/gas analyzer
 Excuse getting off the ignition subject here a little, but this does fit into the equation and hopefully will help in undestanding  more  
 .. .. it all makes sense..really..
 For those interested in a good Frank Mallory/Tom Sheppard article on these FI systems workings, , the March '93 issue of Mercedes Collector has a this info in it.

 You can get it and other back issues for $10 , ea.  . if still available

[TheEngineer]

I did play with the barometric adjuster by removing shims, I leaned out the mixture over the entire range. It takes very litte: .003 inch of shim makes a considerable difference.

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

[Ben]

So assuming you can achieve 30deg at 3000RPM, whats next ?

I mean I assume the 2deg ATDC + 2 deg is a variable to allow you to get a clean idle with correct emmissions, i.e it doesn't really matter where its at once you are happy with it ?

What would the effect of over advanced ignition at idle be, assuming you still have 30deg @ 3k and correct idle speed ??

quote:Some of the vac retards have an outside port/screw to adjust the vac amount...

.......where is this. I have seen that 13/14mm end piece but I assume it is for dissembley rather than rod adjustment ?
I recall some of the Italian cars, with Ducelier dizzies, have a very fine threaded adjustment wheel for triiming the dwell and some also have one for adjusting vacuum. I have never seen anything like this on a 113!!

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

[hands_aus]

Hey Arthur,
That info about the barometric compensator is very relevant. I have never seen any other discussion on richness of air/fuel mix mention it.

I will go to the wreckers tomorrow morning on a self education excursion. I was there last week and saw a car with an 051 distributor on it.
cheers

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

[Benz Dr.]

The barometric compensator adjustment is well know to me but I never said anything about it for fear of everyone going out and playing around with thiers and making things worse. Some things are best left to rebuilders.
 You can do a certain amount of adjustment on this but as you say it's tricky and you can go too far and damage your engine very quickly.

The distributor has no external adjustments. There's a cap on the end of the vacuum control but it needs to be on there and tight. If it's loose or missing you will have a vacuum leak and no advanc control. There's a screw unde the cap but I never open this up or touch it. This is pre set at the factory and needs no adjustment - it either works or it doesn't.
Total advance is one thing but how smoothly the dvance curve moves upwards is even more important. It should move in a nice progressive pattern without and flat spots. This is nearly impossible to determine under running conditions with a timing light.

Daniel G Caron

[A Dalton]

The outside adjustment on the vac box is for the start of the  vac range movement .
 Although we never see these specs in the US version manuals , I
was lucky enough to get this info for Euro Versions from Germany through Achim of this group. [ Many Tnx on that ,A]
 I finally got the specs translated with his help and a fellow that works for me.... I have alway been interested in  seeing if there were different spec recommends on Euro versions, mainly due to the difference in the cam and timing bearing plate not seen on US distributors  ...anyway,

 The adjuster specs for this screw are vac movement/start at approx 100 mm/Hg and full range/end at 300 mm/Hg.
 This equates to aprox 4"/Hg and 12"/Hg , respectfully, so Dan C. has it about right .  This adjustment is far beyond running parameters on the retard system, but more important on a vac advance system...
 One could use the end spec to tweak the final +2 degree tolerence , but not neccessary and , as D.C. states , better left alone if no one has fooled w/it...

[A Dalton]

More info

 http://www.slmarket.com/fuel.htm

[Bob G ✝︎]

The bosch number on my ignition distributor single points is 0231 185 009 and the condenson is 237330318 any ideas which car this came out of and how does it compare to an 051 distributor. Alumminun disrtibutor.

Bob Geco
1968 280SL

[TheEngineer]

Hi Bob: I got that all sorted out: The Bosch p/n 0 231 185 009 Distributor (MB 002 158 3801) replaces the Bosch p/n 0 231 116 051. The replacement has an aluminum housing and a fixed (not adjustable) Vacuum retard. The condenser p/n is Bosch 1 237 330 318 and it is very expensive. It has the green wire attached to it. The points p/n is Bosch 1 237 013 112. If you have any questions call 888 667-1042 that's Bosch parts look-up. The alu distributor is still available from MB at $1,640.00 The old iron one is no longer available from the dealers as far as I've been told. But it's better IMHO.

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

[ja17]

Hello Bob,
The "009" aluminum distributor was one of the correct replacement distributors for the "051" and the "062" at sometime. Since then several other numbers have replaced it. My 1972 "Technical Data Booklet" still shows the  "051 as the only distributor number for the 280-SL up until this time. However I have a Bosch catalog which lists the "062" in the latest 280-SL engines and a "067" as its correct replacement. I would guess the "009" aluminum distributor came next? It seems many other 280-SLs now have this distributor installed.
These different distributors may require different combinations of points and condensors than supplied with in the original "051" distributor! Keep recordes or samples so you do not get the wrong parts.

Joe Alexander
Blacklick, Ohio

[TheEngineer]

Hi Bob: with a magnifying glass you can see the Bosch part number on all the consumable parts: On the cap it's on the outside, on the rotor it's on the bottom, on the condenser on the top.

1969 280SL,Signal Red,  Retired engineer, West- Seattle, WA

[Mark in KS]

Thanks to DanC, I switched out this 011 aluminum distributor for an 051.  The performance curve is definitely improved and I'm curious as to whether anyone else has had this distributor on their car.  We're talking about a 127 engine (230SL).

Mark in KS

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[rwmastel]

quote:Originally posted by Mark in KS

The performance curve is definitely improved and I'm curious as to whether anyone else has had this distributor on their car.  We're talking about a 127 engine (230SL).

Has anyone else had which distributor in their 230 SL?  The 011 or the 051?  The 230 SL should have an 051 distributor.

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

[J. Huber]

Rodd, I think there were five different types for the 230SL.

IFUR.6 0.231.116 046
IFUR.6 0.231.116 047
IFUR.6 0.231.116 050
IFUR.6 0.231.116 051
and the earliest (and rarest I understand):
VJUR.6.BR49T which I have in my 1963.

Fortunately it has never given me any trouble.

James
63 230SL

[Bob G ✝︎]

I got an education on early Bosch distributors and the 051 distributor and how it works and what goes wrong. This is a learning curve for me I even learned that the distributor is cast iron and black with the bosch logo on the side.

Now perhaps I can understand some of these post.

Bob Geco