Volkswagen: 1978 vw bus, aircooled vw engine, fuel air mixture

Question
I just bought a 1978 bus champagne edition all original, the engine runs very well, after driving for a while the engine loses power and starts to miss. Is is possible to overheat? What can I do to fix this problem. I am pretty mechanically inclined but know very little about air cooled vw's. Thanks

Answer
Sounds like carburetor icing, which oddly can occur between 20 and 70 degrees F and when there is sufficient humidity.  The Venturi effect inside the carb drastically lowers the temp of the fuel/air mixture, which if the carb itself is too cold, can cause vapor in the air to condense into ice and to gradually build up under these conditions, which eventually chokes off the carb.  When the engine stops sucking, the ice eventually melts and everything runs great again.  Because the carb on an aircooled VW engine is not directly mated to the engine block like on typical water-cooled engines, and therefore cannot get heat from direct metal to metal conduction as efficiently, additional carb heat is normally required to prevent this from happening.  This can occur with an after-market (non-original) carb without heat tubes(this bus is all original?) or any setup that doesn't allow proper carb heating.  Start by researching your engine code (stamped on the case below the alternator) and find out if you have the correct/original engine/carb setup. There might be a non-standard spacer/gasket under the carb also.


Ooops, forgot it would be fuel injected for this year.  Forget the above comments then, sorry I'm stumped for now.