Author Topic: 230SL distributor vacuum advance against cylinder head  (Read 4363 times)

RoyB

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230SL distributor vacuum advance against cylinder head
« on: December 07, 2015, 19:32:48 »
All

I recently installed the Hot Spark Electronic Ignition in my 1963 230SL which uses a Bosch distributor # 0 231 116 046.
The distributor has the vacuum advance facing the rear as shown in the attached image.
The issue I am having is the vacuum advance has to be rotated against the cylinder head to get the timing close.  I still need to rotate the distributor further to get the timing where it needs to be.
According to the Tech Article, I can rotate the Distributor 40 degrees, but I am having difficulties following this thread.
I take this to mean I can remove the distributor then use a magnet to pull the drive gear out, then rotate the gear one tooth.
This is shown in the second image.
Is this correct?  Any feedback is appreciated.
Thanks

ja17

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Re: 230SL distributor vacuum advance against cylinder head
« Reply #1 on: December 09, 2015, 02:42:47 »
Hello Roy,

Yes, you can rotate the gear as needed. For final installation, the most important parameter is that the rotor is pointing to the "slash mark" on the distributor rim, when the engine is ATDC #1, compression stroke. Be very careful to note that the slot on  top of the timing gear is slightly off set to one side. The two cogs on the distributor bottom are also slightly off-set. Be sure to match them up correctly. They can be forced into place 180 degrees off if you are not being careful.
As far as correctly orientating the distributor, you can look at some original photos in the factory BBB to get the exact orientation of the distributor and its advance unit. The orientation is different with the early vacuum advance units and the later vacuum retard units. In every case the rotor should point to the slash mark on the rim at TDC #1 compression stroke. With vacuum cell orientation correct, you should have enough range to correctly adjust your ignition timing.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

RoyB

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Re: 230SL distributor vacuum advance against cylinder head
« Reply #2 on: December 09, 2015, 16:18:06 »
Thanks Joe.  I appreciate your response.
Just needed to know if there was anything unusual in there such as a spring or the like.
Is this issue common on these cars?  The engine was supposedly rebuilt in 1995, and has very few miles on it since the rebuild. 
Maybe a stretched timing chain, but these typically last for a very long time.
I think it is a numbers matching car, but I will need to verify the serial number to make sure. 
There is another 230SL local, and his engine components and distributor look decidedly different than mine.  Mine is serial number 211 in 1963.
The car is at the frame shop getting repair panels installed where the weep holes closed up for draining the tonneau cover.

ja17

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Re: 230SL distributor vacuum advance against cylinder head
« Reply #3 on: December 12, 2015, 05:37:31 »
Most likely the distributor was oriented in the wrong directions during previous repairs. The 230SL had at least five different distributors used over its production. Some were vacuum advance units and the later were vacuum retard units. The "046"  is a vacuum advance distributor. With this distributor, the vacuum cell is oriented pointing toward the back of the car (6 o'clock).  Later vacuum retard distributors had their vacuum cells pointing forward toward the radiator,             (1 o'clock). With the distributor oriented correctly you should have plenty of room for timing adjustments.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

ja17

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Re: 230SL distributor vacuum advance against cylinder head
« Reply #4 on: December 12, 2015, 15:09:53 »
Here is a pic of the correct orientation of a vacuum advance distributor on another 230SL....
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback