mk1-forum.net

As a new member here I thought I'd convey a tip that's helped me for years on. If your car is in storage or just infrequently driven, especially as of late, your carb float bowls with an external vent tube on the float bowls, can allow the petrol inside to evaporate over time. Given enough time the condition will worsen rendering the needle completely stuck in the jet, requiring a complete cleaning and rebuild kit to remedy the situation. After the rebuild of the carbs on my S, as a result, I since added a simple vacuum cap to the float bowl vent tube whilst not running the car which keeps the fuel therein from evaporation, saving future unnecessary carburettor rebuilds.
Here's a photo from that exercise, note the yellow cap Another photo in situ, this time noting the black vacuum caps

Worth mentioning is the car won't start unless the caps are removed...