Tks for the photos, good quality.
I remember having a 1960 European model VW beetle. It had the semaphores on the body side pillars and you mentioned the reserve tank. Mine had that also. There was a small lever on the floor to the right of the gas pedal you pushed with your foot when the fuel tank level dropped below the standard port. That opened a lower port to allow the rest of the gas to flow to the engine. So in a sense there really was no reserve tank just two discharge ports.
Since there was no fuel guage on the dash the car also came with a fuel tank
'dipstick'. It was an aluminum ruler about maybe 20" long graduated in liters. Since the gas cap was inside the trunk of the car you opened the hood, removed the gas filler cap and dipped the ruler. Much like an engine oil dipstick but it told you how much gas was in the tank.
Once when working on a customer's kombi bus I noticed he had a complete disassembled engine in boxes in the vehicle. I asked him if he wanted to sell it. He did and I bought it straight away. Discovered it was an Okrasa engine from a VW specialty engine company in Germany. Put the engine together and into the erstwhile 36hp Euro bug. It was a screamer. In 1970 bought a new BMW 2002 so didn't need the VW any longer. Sold the car minus the engine to another mechanic and the engine to another VW owner.
As Paul Harvey used to say;
'Now you know the rest of the story' BTW, if anybody needs some ancient VW parts my 60 y.o Snap On tool box is loaded with them. Anybody need a transporter (bus) pressure plate?
VW semaphores
Okrasa power
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