HELP:Distributor P/N is strange

[TheEngineer]

To Dan Caron & whoever else desires to reply:
I just took the distributor out because the allen head screw which secures the housing, and which should be free and accessible for adjusting the timing, was damaged. Wanted to replace it while I had the hood off. My BBB says the car should have Bosch P/N 0 231 116 051   JFUR6(R)  but the distributor is marked: 0231 185 00   JFU6   I called my friendly MB dealer and was told that for this car I should have 002 158 3801. I adjusted the timing per the book: 8º before TDC with vacuum disconnected and checked that, with vacuum connected, it was between 8-14º after TDC at idle (700RPM). At 1500 RPM it advanced to about 15º, all of which is per the book. The car runs fine. Question: Where does the distributor I have in there come from?



1969 280SL,Signal Red, A/T, P/S, A/C, Both tops.    Ret. engr. 1967 230SL - Sold

[ja17]

Hello,
It looks like your bosch part number is missing the last digit. The Bosch part number is ten digits. Look again it may be the #0 231 185 010  The dealer has given you the Mercedes Part number which is not on the distributor but this in fact may cross over to the bosch number on your distributor.
 Mercedes and Bosch do not supply the  original distributors. The replacements are different numbers and may require entirely different contact points than what originally  came with the car. There has been a lot of discussion on the subject. If you do a search you will probably find more than a night's reading. The USA emission cars used different distributors after about 1969 than the other cars. Normally the distributors are identified by the last three digits of the Bosch number. I have seen these numbers come up from conversation with other listers with 280-SL's ; 051, 062, 067, 009, 010. In general the aluminum housing distributors are replacements or the latest version 280-SL. The 051 have a steel housing. Dan Caron does a fine job of rebuilding the original distributors.
Many owners order points for their cars only to find that they do not fit because the original distributors have been changed.

Joe Alexander
Blacklick, Ohio

[TheEngineer]

Thank you Joe for the comeback: You are right, I misread the number: The last three digits are 009. It has a steel housing. I have ordered points,P/N 01-007, we'll see if they fit.

1969 280SL,Signal Red, A/T, P/S, A/C, Both tops.    Ret. engr. 1967 230SL - Sold

[Benz Dr.]

Hi all and thanks for the plug, Joe.

The 051 distributor is one of the most commonly used units on 113 cars. They were seen from about 1965 until mid 1969 and were used all the way to the end of production on Euro cars. NA cars mostly used the aluminum 062 after mid 1969 I believe.

051 units are vacuum retard in that they have vacuum applied to the cell only at idle. As soon as you start to throttle up the vacuum shuts off so the distributor plate will move against rotation and ignition advance will take place. The vacuum advance is probably over at 1200 RPM. I set the vacuum cell pull rod to give about 10 degrees of advance for most units. This can be changed by moving it in or out to the correct amount.

The mechanical advance portion is done by a pair of fly weights that are underneath the plate that the points sit on. There are two small springs that sit just beside the fly weights that are hooked on to these small arms on each side. These springs will get weak over time and will either make the flyweights move out too quickly or will prevent the weights from returning to their resting or idle position. This in turn will cause irratic idle speed - fast one time slower the next because the weights are sticking or not returning properly. The arms can be adjusted so that the springs have more or less tension and this will change the point where advance starts. This can take a fair bit of time just to set this up if it's off a long way. The actual weight of the fly weights determines which distributor you have and all the weights have numbers on them which are probably in grams. Some units have two different size of weights which will give two seperate advance cures - one up to about 2,500 and then one that comes in at a higher speed around 4,000. It's posible to design custom advance curves. Mechanical advance is set at 20 degrees on the 051 so that you have a total of 30 degrees advance.

 Sometimes the cam will get siezed on the shaft and there will be no mechanical advance at all. I rarely see this on 113 cars but have seen it several times on 107 cars. Freeing this up is NOT easy. Make sure you add a few drops of oil to the felt wick under the rotor and a bit more to the small oiler at the base of the distributor body.

The later 062 units work basicaly the same way except the vadvance curves are different. The vacuum portion has a much wider swing on it - somewhere around 15 to 20 degrees. I think the mechanical portion is smaller - maybe 10 to 15 degrees.
This distributor works by mechanical advance first and then at about 2,200 RPM it's all done.  The speed relay will act on the switch gear which shuts off the vacuum signal and the distributor will instantly advance to maximum at this point. Since there's a number of elctrical componets as well as thermo switches it's more than possible that none of it works and you've been driving around with no distributor advance, or at least very little.

Hope this helps to answer a few of your questions.


Daniel G Caron

[Naj ✝︎]

Just to add that the 0 231 185 009 is the alli bodied distributor (MB part# 000 158 3801) that supercedes the 0 231 116 051 cast iron bodied distributor.
So you have the correct distributor.

Points set for '009': Bosch 1 237 013 112  (MB 000 158 3990)
naj

65 230SL
68 280SL

[TheEngineer]

To all you knowledgable Gentlemen: Thank you very much, especially Dr. Benz, your reply would qualify as a term paper at automotive engineering school. Accordingly, I have printed it out and it goes into my file: "Things to keep" Took the car out yesterday evening at 10:30PM. Our freeways are empty by then. Wound it up to 75MPH in 3rd. Runs wonderful !

1969 280SL,Signal Red, A/T, P/S, A/C, Both tops.    Ret. engr. 1967 230SL - Sold

[Benz Dr.]

Well, he doesn't have the right distributor at all.

 It will work but has to be set up differently.
The 051 unit has a 38 degree dwell angle and the aluminum units are usually 30 degrees - don't make that mistake or they'll very poorly.

 The early unit has no switch gear and the advance curve is different. Putting this later unit in the car will make it advance too quickly and at the wrong time. You're far better off using the cast iron unit if your car was originally made that way. The later unit is OK if the car has all the gear that's working as it should.

The later unit will work ( almost anything will work to some degree ) but not like the right one.


Daniel G Caron

[Naj ✝︎]

Dan,
From what I can find out, this distributor '009' is NOT the same as the alli distributors used in the last (70/71) US 280sls with transistorised ignition.

The '009' and '007' are replacements for the '051' and '046' respectively.

naj

65 230SL
68 280SL

[Benz Dr.]

I understand that part. I still think they have different dwell angles and may have different advance curves. Maybe someone knows for sure.

Daniel G Caron

[TheEngineer]

This becomes an interesting dialog: I have verified that it is an aluminum housing ( Or should I call it Aluminium?) According to my BBB the vaccum retard is zero at about 100 mm of vacuum and increases to 8 – 14 degrees at about 300 mm. That is easily within the range of my vacuum gauge and I can measure that. The centrifugal advance starts at 1000 RPM and rises to 20 degrees at 2400 RPM. I can also verify that, using the strobe. The dwell angle is now 38 degrees, but I can change it to 30 and see if it makes a difference. Why didn’t you tell me before I put the hood back on?

1969 280SL,Signal Red, A/T, P/S, A/C, Both tops.    Ret. engr. 1967 230SL - Sold

[Naj ✝︎]

We'll to interested to hear about your findings.
naj

65 230SL
68 280SL