Mercedes-Benz Ponton
Solex Carburetor Rebuild
"Lessons Learned"

1- Mr. Will Samples (S&S Imports / Dallas, Texas) said, "Do not touch the mixing supports or jets!." He is right. The one on my front carburetor had the jet and top of the pot metal mixing post missing. The brass jet was found lodged in between the secondary vacuum valve and throttle valve. The missing top of the pot metal post was never found. The rear carburetor’s mixing support/jet was intact, but when I inserted a screw driver into the slot of the jet, it too fell off without any force at all! Since these carburetors had been rebuilt within the past 6-8 years by local mechanics, I have to wonder if these fractures date back to that time.

2- One of the best things I did for my carburetor rebuild was to decide to find a pair of used, intact carburetors to supply parts (mixing tube supports, etc.). I used these to select the best of each pair to end with one best pair. Henry Magno supplied mine, but others had possibilities for sale as well. With limited supplies for parts from vendors, this was well worth the cost. My search also produced Star Classics as a source for the mixing post supports and another source for the dash pot rubber bellows. I have not verified these, but some of this stuff is out there somewhere. Reference the Links page for contact information.

3- The Mercedes-Benz Ponton website (www.mbzponton.org) has a carburetor rebuild article by Jack Kotrba which is an excellent help as a supplement to the factory workshop manuals. In addition to the Ponton website, the International Ponton Owners Group (IPOG) is also a great resource. IPOG member, Doug Broome, provided a lot of useful information on the subject. Carburetor rebuild kits are available by Royze from several retailers. I paid about $50 for the pair, prices are up a bit. Gordon Lewis also has a good write-up on tuning/adjusting dual carburetors on the Ponton website.

4- NAPA sells a liquid carburetor cleaner in a gallon can. Evil looking stuff but soaking the carburetor parts for an hour or two followed by a brush scrubbing in soap and water does a good job. All passages should be blown out with compressed air, no sharp wires.

5- Several sources recommended rechecking the tightness of the threaded fittings after a period of use. I found this to be true in spades! After rechecking several times initially, I checked still again after 250 miles and found that every single one required further tightening and the main jet for the rear secondary was very loose!

6- There have been multiple entries regarding "balancing" the two carburetors after the rebuild. Two of the meters available are a Chinese made "Unisyn" from Edelbrock and a "Synchrometer" sold by JC Whitney and made in Germany. Both require an adaptor to use with the oval opening of our Solex carburetors. The adaptor is easily homemade of cardboard with foam as a sealer. I found the German one to be easier to use, with more precise measurement of air flow and likely of better quality. After initially adjusting the carburetors as per the manual, the flow measurements were within specs and reproducible.

7- One of the 4 bolts attaching the cover of my front accelerator pump had stripped threads. Len Sokoloff said he had the same problem but the other 3 bolts held the cover/gasket well enough that it did not leak. I decided to hold off on any attempt at thread repair based on his experience but mine eventually leaked. I tried to get the 2 mating surfaces as flat as possible by sanding them over a piece of plate glass. I then used a Permatex Stripped Thread kit (about $8 from NAPA) which uses a two part epoxy. It worked surprisingly well and there has been no leak for several weeks now.

8- After fiddling with the adjustments a few days, idle after warm-up is 750-800 rpm and the difference in starting, smoothness and power is remarkable. So for anyone hesitating to attack a nagging carburetor problem and who has the factory workshop manuals available, I would say go ahead. Certainly, no one could be any more ignorant about them than I was!

- James Pancoast / November 10, 2005