There are quite a few cars that are equipped with a Pierburg or Zenith 175 CD carburetor. In fact, it is a trouble-free gas factory that hardly runs if it is properly adjusted.
There is also little difference between the performance in the summer and in the winter. It is mounted in various, among others MG B's that came from America and in a heap Volvo's of the type 240. They are usually equipped with a manual choke, but there are also versions where the choke control is automatic. All of this has nothing to do with the occasional problem. The fut is completely out of the car and the engine crushes it to make speed. It is only with the greatest possible effort that it is possible to move forward and it is impossible in any way to drive faster than 50 kilometers per hour. The same problem can also occur when the contact points hardly open and close anymore or when the ignition is off from time. Usually this will be accompanied by thuds and bangs. It could also be that very little fuel is supplied. Years ago I was waiting in front of a traffic light with a car with such a carburetor. The light went green and I gave gas. But very little happened. With great difficulty I moved forward and I drove home very slowly. Once there, it turned out that the car was running well at idle. That is why all the options just mentioned were checked. After all those options had been investigated and lost weight, I got my hands on my hair. Good advice was expensive. What now? In no book could I find information that made the problem comprehensible and soluble. Until someone asked me if the rubber membrane on the piston of the carburetor was still intact and had not hardened. It was hard, but it still looked whole. I got the tip to dismantle it anyway and hold it up to the light to look for damage. And indeed. It had two holes the size of a pinhole. A fresh, flexible membrane was purchased from the dealer and fitted correctly. (There was a lip on it that fits exactly into the lid of the carburetor). Great was my joy when it turned out that the car reacted again to the gas pedal. Because of that small hole the vacuum effect was disrupted and the piston was no longer sucked up, so that very little mixture was available. The membranes were not that cheap but at least they could be driven again.
Photo and text: Jacques van den Bergh