Help? Weird ignition (points) problems - '68 220 - Page 2 - PeachParts Mercedes-Benz Forum

Arthur Dalton · #16 02-11-2007, 01:12 PM

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..and they were infamous for that..

Another possible is guys disconnect the Ballast and run the coil with bat voltage..that will also burn the points.

The reason CTH ask about the cond wire is b/c there was a couple of ingition changes from 68-72, where they went from a standard point/ballast system , to adding a Transistor switchgear ignition. Those are the ones with the long green capacitor wire and they were famous for shorted capacitors. The idea of the switchgear was to lower the voltage to the points as they only had to trigger the transistor in the switchgear, putting the primary load/draw on the transistor instead of the points. The problem with these systems is even though you now have point longevity due to lower voltage demand, you still have mechanical switching and dist cam/point block wear..Mod to electronic switching [ Hall Effect or Optical] completely eliminates the mechanics of the points.. an marked Tech improvement . Your lawnmover doesn't even use points anymore, and for good reason........
My personal preference is Optical due to high energy at both cranking and low rpms, but even the hall effect are very reliable.

Mr Basil · #17 02-11-2007, 02:15 PM

On mine there was a screw holding a bracket to the breaker plate vacuum advance arm and I put a ring terminal under the screw. I looked at your picture and didn't see a convenient screw on yours (doesn't mean it's not there. And I should mention mine is a 68 280 SE with the 6 cyl FI engine and looks alot different). You could always remove the plate and tap a hole into it or try soldering it again. It would have to be really clean and fluxed of course.
Looks like a pain.

Good luck,

Basil

t walgamuth · #18 02-11-2007, 04:33 PM

IIRC the 190sl of that era had two carbs.

maybe you have a set of those.

tom w

aircap · #19 02-11-2007, 04:39 PM

OK, I made a new ground strap and attached it to the base of the point set via the lockdown screw. Seems to be working. Installed the new condensor, which is slightly different than the old one, but also seems to be working. I regapped the points to about .016.

The car fires up and idles really nicely. On the road, though, it's got no pep at all...it pulled much stronger with the old crapped-out points (at least until they finally vaporized).

How much do you think having a new set of points (and a fresh gap) affects overall timing? Should I regap to a new spec, or keep the current one (the book says .016-.020) and adjust the timing a little? I don't have a strobe timer handy, by the way, but can get one in my hands in the next couple days.

Thanks to everybody who has replied. You guys are aces!

aircap · #20 02-11-2007, 06:46 PM

Crapola... I tried several different point gap settings, to no avail. In fact, it just keeps running crappier. I even tried swapping the old condensor back in, and now it's got more power again, but hesitates and backfires under load. Starts and idles like a dream.

Heavy sigh. I just hope I can make it to work tomorrow...I met an old MB mechanic who actually has a shop near my office, and he said I could bring it by tomorrow. I feel like I'm this close to having this straightened out...but not quite. I look forward very much to having a smooth-running ignition system.

I'm getting more interested by the minute in a Pertronix-style system, but can't find any identifying marks on my distributor. Can anyone tell from my pictures what kind/model it is? I may start a new thread about that issue if no one stops in here with an answer.

Thanks again, everybody. I will persevere.

Arthur Dalton · #21 02-11-2007, 06:52 PM

There should be an ID plate on the side of the dist.

Starting too many threads on the same problem will limit answers .
Many of us just quit when a poster does that..it can get confusing.

aircap · #22 02-11-2007, 07:18 PM

With a flashlight I was able to barely make out a number...but there may be more digits (at the beginning of the series) obscured by the vacuum pod. Here's what I could make out: 231 115 065. That "2" might be a "7". Does this ring a bell for anybody?

Arthur Dalton · #23 02-11-2007, 07:29 PM

JFUR4 -0231-115-065

That is pre emiisions standard Bosch dist.
Give that to Pert and they will giv you the correct Hall module.
That is the original dist for that chassis.

aircap · #24 02-11-2007, 07:44 PM

Arthur Dalton, you are a prince.

Arthur Dalton · #25 02-11-2007, 07:48 PM

I will have to show that one to the Wife.........been tryin' to tell her that for years ..........

cth350 · #26 02-11-2007, 10:47 PM

Mark's right; my error on the carbs. I had forgotten about the early dual solex setup. I stumbled across the engine manual this afternoon and paged through it because of this thread and there was the nice picture of the dual solex. Also the stromberg, which doesn't show up until 1970.

Every time you change the points, you need to retime the motor. If you skipped that step, it would explain the odd behavior.

The 0231115065 distributor is the US model from '68/69. Take the motor up to 4,500rpm without the vacuum attached and set the timing to 43 degrees. Then check the timing at 1,500 rpm (23-30 degree), and 3,000 rpm (31-38 degrees).

Finally, recheck at idle (800rpm) WITH the vacuum attached and you should see 8-12 ATDC.

With the vacuum disconnected, plug the line. Note that it's a retard not an advance, so if you checked idle with it disconnected, you should see it shift over by 19-25 degrees from the setting I mention above.

For completeness I should mention that at starter speed (about 200rpm), the timing should read 7btdc w/o vacuum. That's useful if the thing goes totally non-running or if you pull the distributor and need to put it back.

-CTH

aircap · #27 02-11-2007, 11:09 PM

cth350: Thanks for the tips on timing. That's good stuff!

So...if it runs great at idle but hesitates and backfires under load, does that mean it's too far advanced or retarded? Or could it be either with those symptoms? Looking down on the distributor, which way (clockwise or counter-) do I turn to advance/retard? I'm gonna go consult my manual and see what it tells me on that front.

As I mentioned before, I plan to take the car in to have a guy look at it tomorrow. I'll certainly post an update. Thanks again, everybody.

250 Coupe · #28 02-11-2007, 11:55 PM

I wonder if the mechanical advance is bound up by the ground strap you had trouble with earlier. The plate the points mount to needs to turn freely to allow the advance to work. Don't mess with the timing until you verify the plate can move freely.

Also, the advance weights could be messed up and either sticking or flopping around.

Michael

Arthur Dalton · #29 02-12-2007, 05:23 AM

If you plan on owning one of these older Benzs, go to ebay and get yourself an old style timing [strobe] light ..I see them for $5..they come in handy for old igniton systems.........
Then you can easily check the advance/retard along with proper timing.
..set it as CTH recommended ...and I also suspect the ground strap not allowing the advance plate to rotate...easy checks with a strobe....................

Here's a brand new one NIB starting at a buck...will prob go for $5.. >>>

http://cgi.ebay.com/ebaymotors/CRAFTSMAN-DIAGNOSTIC-TOOLS-INDUCTIVE-TIMING-LIGHT-NIB_W0QQcmdZViewItemQQcategoryZ43989QQihZ019QQitemZ290082537375QQrdZ1

aircap · #30 02-12-2007, 01:18 PM

Well, I checked this morning before driving to work, and my homemade ground strap wasn't binding the advance plate. However, the plate did seem a little sticky. I put a little spray lube on the ball bearing in there and the vacuum plunger...not much, but enough to where when I advanced the plate back and forth by hand a few times, it seemed smoother and easier.

I used to have a timing light, but a bunch of my tools were stolen a few years back...just never got around to buying another, even though I only drive old cars. The last couple times I've needed one, my buddy Jeff has helped me out. (He has a dwell-tech, too!)

At any rate, with the old condensor back in place, it drove pretty well on the way to work this morning. I do think that now the timing may be off. I'll holler back here after I have the local guy take a look.

Thanks again, everybody!