Distributor related problems??

[dcseidman]

Fellow forum members:

  I have been driving my 1969 280SL (4-spd), man and boy, for 45 years this LaborDay weekend.  In that time, it has covered 174,000 miles (13,000 in year one, with the original owner, 161,000 with me in the ensuing 45 years).  Over the past years, the capable service persons whom I had used have all retired or died, and those caring for her today are much more familiar with later M-B cars/technology than with the running gear of a W113.  She has had regular maintenance, including ignition tune-ups, as required.  Over the past year, she developed a distinct "miss" upon acceleration in higher gears, especially on "full throttle" above @ 3000 RPM (I may be 76, but I still enjoy exercising my SL).   Mechanics trying to address the situation seem to "cure" the problem for a day or two, at best.  Last week, a refiling, clean-up and re-setting of the points produced an amazing amount excellent throttle response for @ 20 minutes, as I drove home, only to have the self same "bad behavior" resume when I got her home. 
  I conclude, as follows:  that the distributor's points will not hold their setting very well, due to the distributor simply being "worn out" (hard to believe that a well-made W113 would wear out after a paltry 174,000 miles and 46 years!).  So, my plan is to replace the distributor works with a Pertronix unit, thus putting points resetting into the past.  ANY comments and suggestions are greatly welcome.  [I replaced the points in a 50 year old Rolls-Royce with Pertronix and have had no further problems.]

Thank you.

[Cees Klumper]

Hi David - others with more knowledge than me will surely chime in, but if I were in your shoes I would replace the entire distributor with a 123 unit. If the distributor doesn't hold the dwell/timing settings well, it could be due to worn bushings, flyweights, vacuum unit etc and a Pertronix unit won't solve that but the 123 will, and is a more sophisticated ignition unit alltogether. You can also have the distributor rebuilt, eg by Dr Dan. But I would also look for fuel delivery issues, check the fuel flow and pressure, the linkages and such.
Good luck with the fix, great to see you have had the car for so long.

[mdsalemi]

The only time you should install a Pertronix (or any other electronic ignition) is when everything else is working fine. If you have unstable distributor issues, adding a Pertronix may create more problems than it solves. Get the distributor rebuilt properly, get it working conventionally in a stable and reliable manner, THEN switch to a Pertronix...

That's a lot of time; surely some money and effort, too.

The quick reliable fix to solve all the issues is, as Cees recommends, the 123.

[Scottcorvette]

Different car I know but I have just fitted a 123 distributor to my wifes Karmann Ghia, and it has transformed it. It was always really hesitant when cold and would sometimes sound like misfiring, I replaced plugs and wires, also fitted a new carburettor as that had been buggered about with and repaired, all these things improved it a bit, but the distributor has fixed all the issues and the car starts and runs well from cold, and really performs better than it  ever has.

I will definitely be putting one in my Mercedes when the time comes, my only criticism is that it has the shiny housing and looks a bit too modern, I don't know how successfully the distributor housing would take paint? Its a pity they don't do an anodized black one.

[mbzse]

.../... 123 distributor .../...only criticism is that it has the shiny housing and looks a bit too modern.../...

I use only 123 distributors in my old Mercedes cars, and so do most of my M-B buddies... Many advantages.
With regards to the looks,; I spray paint my housings in semi-matte black, before installation. Takes an expert to distinguish it from a Bosch 051 unit. If you want to be really serious about things, attach a condenser and an oval metal ID shield from an old Bosch 051 onto your 123 housing (w/o connecting condenser electrically of course). This will certainly convince even the expert you have an original Bosch mounted, he he  .

As usual, I urge 123 users to change the coil as well (Voltage is higher and your tired old coil may not take the strain) and also to use the M4 hole in the housing to run a grounding wire over to your engine block. Good ground is essential for the good functioning of the 123 units !  I know one of the guys who participated in the development of the unit, in the Netherlands, so these tips are direct from him !
/Hans in Sweden
.