Carb Preferences

[harryskater]

Anybody have any preference of carbs?
The options are Solex 34PICB - which i've already reconditioned but afterwards found that a part of the casting is cracked and could at any moment fall down into the throttle body.
Or Zenith 35/40's off of the donor car which need some TLC, a different manifold and extra wiring (wire) for the automatic choke heater coil.

Im thinking at this stage it would be ideal to find a single spare Solex 34PICB and stick with the original set up but Im curious about fuel consumption and power between the two designs.

[mercmad6.3]

The older carbs are good simple items, the Zeniths are the spawn of satan and should be burned at the cross roads ,preferably at midnight then showered with the urine of a virgin...(last bit might be hard to find in NZ) .

[pedrocamp]

Great to see the Aussie-Kiwi love affair still exists!

I have a set of Zeniths on my 68 230 W110 and once rebuilt, carefully, they function quite well. I added the later throttle return brackets and removed the return valve, I converted to a constant return. I made sure the tops were flat and spent some time adjusting float levels for correct mixture. What problems should I look out for that makes them evil? I don't have experience with the Benz Solex carbs but plenty of Vdub ones.

Thanks.

[mercmad6.3]

They were never any good,I have worked on them on Both mercedes and BMW since the late 1970's .In the old days it was easier because you simply took them off the engine,set them on a jig,replaced anything that looked bad then set them on the flow bench. The latter being the only way to get them to work correctly They would last about 18 months then the customer would be back with more complaints about bad starting,high fuel consumption, hard starting when hot ,flat spotting lower top speed.
Back then these cars were driven hard with many covering up to 100,000 miles every 18 months to two years. (never believe what the odo reads...) . This meant the housings would be warped often, dash pots leaking ,linkages worn and do not forget,the customer wasn't getting rectification work done for free. Now 40 plus years later with many of them tottally worn out from the base gasket upwards folks want them to perform like the fuel injection on the wifes camry...it aint gonna happen.

[pedrocamp]

I've had my car about a year and a half, rebuilt the carbs about a year ago, I suppose I am due for carb issues! I drive it every day. Mechanically the car is in nice condition, I've rebuilt everything but the engine block/head and tranny since I bought it. I am getting about 15 - 19 mpg, 6 - 8 kpl, is that about the range for an auto trans? Terrible when compared to new cars but I figure not too bad for this old car. My dad had a 67 230 back in the mid 70's, I was in my teens, and I do remember him tuning the carbs a bit but generally the car ran pretty good. His memory is going so he isn't a good resource unfortunately. Thanks for your help.

[harryskater]

Thanks for the comments, Im also familiar with Solex from working on VW's. The Zeniths however look pretty involved and i think id like to avoid using them unless they improve power substantially or reduce fuel consumption. Otherwise im happy to stick with the little Solex's!

Does anybody know about Fuel pumps for M180 Engines?

My engine had a blanking plate over where the pump was and has an electronic system rigged up.
Under the blanking plate is a Horizontal Cam.
And this is the fuel pump from the Donor M180 Engine..



I dont see how this pump would work with this engine. Surely it would need something like a vertical cam to operate..

[mercmad6.3]

The part that is missing is the alloy right angle mount which bolts to the block ,and then the pump bolts on top of that. There is a small push rod in the block. The big problem with the mechanical pump is that it must be in good overall condition and the lines from the tank to the pump must be secure with no leaks which can allow air to be sucked in too. When it's all good ,the pumps are very effective .A lot were replaced with Facet pumps to save replacing dodgy fuel lines in the past.

[Carpenterman]

I went through the fuel pump "boogie" last year on my '66 230 (180.945). I was having hard starts after the car sat for a while and was worried about the wear on the starter and the battery.

My research showed that the Solexes were known for evaporation of the fuel from the carb bowl and there was also an issue of gas migrating back in the fuel line to the tank. The older Pierburg fuel pump on the Ponton actually had a priming lever on the pump to fix this problem. You would think that the migration issue would not happen with the check valve in the pump but it seemed that it did. I had checked the hose/fittings for leaks but it was all good.

I could not find an original equipment Pierburg pump after a pretty exhaustive search, but I did find a Vaico pump for about $35 that was specified for my engine. I didn't like it--although it worked, it was cheesey and I still had hard starting. By the way, if you are going with any mechanical pump be sure to check the cam clearance between the pump and engine to be sure it's in tolerance.

My final solution was a Carter electric fuel pump. Pretty easy to install and about $90. You'll have to make a blanking plate for the old fuel pump mount. The pump is rather noisy, but now I turn the ignition on and wait until I hear bubbles in the fuel tank.

Car starts immediately now.

[wbain5280]

Check here for Solex carb info:

Mercedes-Benz Ponton Workshop © www.mbzponton.org

You may also be able to get another.

You can always swap the carbs for throttle body and Megasquirt, a DIY fuel injection system.

http://www.peachparts.com/shopforum/vintage-mercedes/238292-m115-t-b-i-conversion.html

[Carpenterman]

Wbain is right on the money. The Factory Service Manual also has a very complete section on the 38 PDSI Solex (on disc Volume 3, starting on page 13). Your car with the 34 PAJTA or 35/40 INAT can probably be found on disc Volume 2.