1970 280S Choke ??'s - PeachParts Mercedes-Benz Forum

tivoklr · #1 10-14-2007, 11:13 PM

I have a 1970 280S which is going to get some use this winter in a cold environment, and I was hoping some experienced person here could direct me as to setting the chokes correctly on the Zeniths on this car.

Car runs pretty well, has started for me on mornings like 30F degrees, with a little pumping. The rear carb was missing the funky bent wire that went from the choke mechanism to the butterfly but I replaced it. The height of the same wire on the front carb is suspect also.

Wife loves car, wants to be able to start it after working the night shift without any BS starting it...

Thanks for any advice.

p.s. we have a saying, "the Mercedes is the first vehicle out of the driveway every day."

p.p.s. just saw a merc diesel commercial on SNF and I WANT ONE...

MunichTaxi · #2 10-15-2007, 11:40 PM

http://www.jaimekop.com/

On a side note, my current choke issue is that when "setting the choke", the linkage doesn't travel far enough to engage the last 'step' (mechanism inside choke cover). I am going to try and re-bush the thottle shafts with brass pistol cartridge cases. I'm not sure what caliber is appropiate (9mm?).

Mike D · #3 10-16-2007, 07:03 AM

I used .38" special cartridges for my bushings. They are a little loose but they made a world of difference on my twin Solex M115. Thanks to one of the board members who posted the size. 9MM might be a better fit. Keep us updated.

todds · #4 10-16-2007, 10:00 AM

Look at that zenith link and follow all the directions. THEN fine tune your carb for the winter. Just keep at it, making very small adjustments and evaluating them. Eventually your car should start and run with zero fuss and only a modicum of pumping to set the choke (like ONE).

Once you get it to start everytime, the real trick is to keep it running in all temps. The elusive adjustment for that is usually the vacuum pull-off of the choke plate which either engages too little flooding the engine (unlikely) or engages too much opening the plate too wide and stalling it out when cold (more likely)

http://www.jaimekop.com/CarbManual/Page24-25/index.html

The last pieces of the puzzle are the heat riser flaps in the exhaust manifolds. These cause no end of headaches and problems in the summer but in the winter give that last little push to make cold weather starting/running perfect. A lot of people live without these entirely and have no issues even in winter and common advice is to shut them permanently.

Don't worry though, it IS, of course possible to get it to start the way you described. It's a Mercedes, it'll run like a swiss watch when you get it straight. Your ignition system also needs to be in great shape.

tivoklr · #5 10-16-2007, 02:35 PM

My ignition system was just revamped with a Pertronix which has improved the running of this car markedly. The transistor switch box thing gave up the ghost and the new coil and Pertronix unit were cheaper than a used part, so why not...

At least that's one variable out of the way.

I will start slowly and follow the manual, this morning was the coldest day so far that I have tried to start it, the air temp was above freezing but the car had a lot of ice on it from condensation, and it took a few tries but then she started.

I will work little by little and report back. Thanks to everyone.

ggenovez · #6 10-16-2007, 03:25 PM

To add to what Todds said, you can pull a vacuum from the vacuum advance line and the rear dashpot with a t fitting and a mighty-vac, vacuum generator... to simulate the engine running, or if possible pop the choke housing and pushe the arm back by hand. and set the gap.

Personaly, I'm a clutz and I don't like putting drill bits into a carb while the engine is running.