Greetings!
I am trying to revive my 1966 230S Mercedes-Benz with Zenith 35/40s.
I hoping I can get some help - even though this application is for a Mercedes.
There is very very very little information available from Mercedes sources - luckily I found this fine forum and the technical documents posted. It's been very useful. Basically these carbs are about as simple as Zeniths can be compared to the E9 version. The ONLY electronics are the bi-metallic spring for the choke. There are no sensors/switches or emissions devices like the BMW have. I suspect later model MBs probably have some of the this - but not my 1966.
Here's the diagram - except I do NOT have the vacuum actuator 408/410 on the rear carb. My car is a manual - guessing maybe the automatics may have had it.
Backstory of the car is my father bought it new. I learned to drive manual transmission on it and have wrenched on it extensively over the past 30+ years. Unfortunately my other cars, and too many of them, have taken priority and the 230S has been largely neglected for 10+ years. A couple months ago.......after years of procrastination...I devoted 100s of hours to get this thing running again. I'm almost there - just trying to fine tune the carbs. Cold starting, idle, synchronization, and general drivability are good. My two outstanding issues - are the "high idle" and the vacuum secondary diaphragm - I have new diaphragms ordered. It actually runs surprisingly well on 1 barrel. The biggest annoyance - which I believe is the choke "high idle" is that until the car warms up I have to be very careful feathering the throttle several times from stop signs/lights for the first 5-10 minutes or it will die. After that initial 5-10 minutes I can drive it normally.
As I was studying the documentation and adjustments I noticed something different between the front/rear carbs with the choke - the unit on the rear carb rocks slightly compared to the front carb?????
Here's a couple videos to illustrate:
Both carbs -
Rear carb -
I'm not sure what is correct w/ different behavior on the front vs. rear carb and I can't find anything in the literature. Should the choke mechanism move or not move???
I found that the front carb choke mechanism is missing the adjusting screw/spring for the fast idle (286/287 in the diagram). I'm in the process of tracking those parts down - which might be the issue but would be helpful to know if the choke mechanism should be rocking like it is on the rear.
One complaint my father has had since day 1 - the A/C compressor can kill the engine at idle. The simple fix is to increase the idle RPM but I've thought a better solution might be to interrupt the signal to the A/C compressor clutch at idle.
I'm thinking about picking up a used/parts carb on eBay which will hopefully supply the spring/screw I need as well as the linkage (mine doesn't have the stop circled in red) and vacuum actuator. I would then modify the actuator to an switch of some type that would be open at idle and closed when off idle. This way I could shutoff the A/C compressor at idle. Before I do so....seeing how the BWM carbs have evolved - is there a better solution from the BMW I could leverage?
EDIT - should have mentioned I thoroughly cleaned and rebuilt these carbs w/ the Walker kit (which is 70% garbage IMO). I also added a Ignition 123 distributor, new spark plugs, new fuel pump, and all new fuel lines.
Thanks for your time -
Dave
1966 230S
2002 E46...track car
I am trying to revive my 1966 230S Mercedes-Benz with Zenith 35/40s.
I hoping I can get some help - even though this application is for a Mercedes.
There is very very very little information available from Mercedes sources - luckily I found this fine forum and the technical documents posted. It's been very useful. Basically these carbs are about as simple as Zeniths can be compared to the E9 version. The ONLY electronics are the bi-metallic spring for the choke. There are no sensors/switches or emissions devices like the BMW have. I suspect later model MBs probably have some of the this - but not my 1966.
Here's the diagram - except I do NOT have the vacuum actuator 408/410 on the rear carb. My car is a manual - guessing maybe the automatics may have had it.
Backstory of the car is my father bought it new. I learned to drive manual transmission on it and have wrenched on it extensively over the past 30+ years. Unfortunately my other cars, and too many of them, have taken priority and the 230S has been largely neglected for 10+ years. A couple months ago.......after years of procrastination...I devoted 100s of hours to get this thing running again. I'm almost there - just trying to fine tune the carbs. Cold starting, idle, synchronization, and general drivability are good. My two outstanding issues - are the "high idle" and the vacuum secondary diaphragm - I have new diaphragms ordered. It actually runs surprisingly well on 1 barrel. The biggest annoyance - which I believe is the choke "high idle" is that until the car warms up I have to be very careful feathering the throttle several times from stop signs/lights for the first 5-10 minutes or it will die. After that initial 5-10 minutes I can drive it normally.
As I was studying the documentation and adjustments I noticed something different between the front/rear carbs with the choke - the unit on the rear carb rocks slightly compared to the front carb?????
Here's a couple videos to illustrate:
Both carbs -
Rear carb -
I'm not sure what is correct w/ different behavior on the front vs. rear carb and I can't find anything in the literature. Should the choke mechanism move or not move???
I found that the front carb choke mechanism is missing the adjusting screw/spring for the fast idle (286/287 in the diagram). I'm in the process of tracking those parts down - which might be the issue but would be helpful to know if the choke mechanism should be rocking like it is on the rear.
One complaint my father has had since day 1 - the A/C compressor can kill the engine at idle. The simple fix is to increase the idle RPM but I've thought a better solution might be to interrupt the signal to the A/C compressor clutch at idle.
I'm thinking about picking up a used/parts carb on eBay which will hopefully supply the spring/screw I need as well as the linkage (mine doesn't have the stop circled in red) and vacuum actuator. I would then modify the actuator to an switch of some type that would be open at idle and closed when off idle. This way I could shutoff the A/C compressor at idle. Before I do so....seeing how the BWM carbs have evolved - is there a better solution from the BMW I could leverage?
EDIT - should have mentioned I thoroughly cleaned and rebuilt these carbs w/ the Walker kit (which is 70% garbage IMO). I also added a Ignition 123 distributor, new spark plugs, new fuel pump, and all new fuel lines.
Thanks for your time -
Dave
1966 230S
2002 E46...track car
