Mercedes-Benz Ponton Type 220S
Weber Carburetor Conversion

If you are experiencing carburetor problems and view this as the only solution, please step back for a moment. As of this writing, a complete conversion kit is about $850. Before laying out this type of money, you should have performed several tests and repairs before reaching the final conclusion that you have no alternative.

In many cases, what appears to be a carburetor problem is in fact related to intake leaks. Gaskets may be going bad, bolts may have loosened up or you may even have a hairline crack in the intake manifold. I would be especially suspicious if you are having an adjustment problem in which you can get the car to idle well with poor road performance, or the opposite.

Before you do anything else, I strongly recommend that you perform this simple test. Remove the air cleaner and start the car. Let it warm up and settle in at a normal idle. Get a can of carburetor cleaner with the little red jet spray tube.

Starting at the base of each carburetor, carefully spray a stream of fluid directly on mating point between the carb and the intake manifold. If there is a leak, the fluid will be sucked into the manifold, causing a brief change in the air/fuel mixture that will result in a noticeable change in engine RPM and sound. Don't get any into the top of the carb or you will get a "false positive."

Be sure to work your way around the entire base of each carburetor. You should then move on to the mating point between the manifold and the head. Over time, manifolds can warp slightly, or the gasket can deteriorate, or the manifold bolts may have backed off slightly. Perform the same test around the edges of the manifold flanges. Once again, if you experience a change in RPM and/or engine sound, you have found a leak.

If you find leaks, chances are strong that you can solve your problems for considerably less than the cost of a conversion. Treat the situation as a good mechanic should, and fix the obvious problems. Even if you end up doing the conversion, you would still have had to take these steps.

If you have a leak between the manifold and the head, you must remove the carbs and the manifold. Lay a steel straight edge across the flange that attaches to the head. Were the bolts loose? Is it perfectly flat? Does it need to be milled? While it's off, get it tested for micro cracks at your local shop. Can you see odd burn patterns on the gasket?

If the leak is under the carb(s), pull it off and replace the gasket(s). Make sure the mating surfaces are clean and smooth. Try not to drop anything into the manifold openings. Foreign particles sucked into the engine are a BAD THING.

Since you have them off, go ahead and rebuild your Solex carbs. You can do it for well under $100 and step by step instructions and photos can be found on the Ponton Workshop page.

So, for about $100 in parts and gaskets, perhaps twice that if you needed machine work on the manifold, you've corrected your intake leaks and rebuilt your stock carburetors. In most cases, you will have eliminated the need for a Weber conversion and saved yourself a considerable chunk of money. You and your Ponton will be happy campers for many years to come and you don't have to read the rest of this article.

On the other hand, if all of these things don't solve the problem, you will have taken care of the prep work required for the Weber conversion. If your Solex carbs have egged out shaft housings or other problems with the bodies, the cost to have them remanufactured could be extremely high and the Weber becomes the more cost effective solution.

So, you're really serious about this conversion thing. Okay then, let's look at Weber conversions in general. Weber kits are well known and frequently used on virtually all carbureted cars and trucks in the world. The kits allow the installer to retain the original intake manifold, original linkages and original air cleaner canister(s). In most cases, the difference in carbs is not noticeable unless you remove the air cleaner. These kits are clean and relatively easy to install.

Although I have not personally done a Ponton installation, I have installed Webers on several older Toyota land Cruisers. It appears that I am one of the very few International Ponton Owners Group (IPOG) list members with Weber experience and the time to write this up. The basics are all the same from car to car, and this article was peer reviewed by IPOG member Scott Gordon. Scott has done a Ponton installation and has kept this on the straight and narrow. He has also supplied many of the photos you will see here.

For most vehicles, Weber offers a standardized kit at Redline. This means that you would have several sources for kits, parts, accessories and the like for your chosen application. In the case of the Ponton 2.2 liter engine, this is not the case. Two critical components are not available through normal distribution channels.

The heart of the Weber conversion kit is the adapter plate system that mates the Weber to your existing OEM intake manifold. Also important, although not critical if you are handy, is the throttle linkage adapter. Neither of these items are currently being made by Weber.

That brings us to JAM Engineering. The owner, John Moulton has engineered and manufactured the plates and throttle arms for our Pontons. In spite of being the single source, this actually works to our advantage.