Smell of Avgas not unusual in the Luscombe.
It has wing tanks with independent fuel cocks going to a tee and then to the gascolator.
Being an old aeroplane it naturally flies on the chinese manner (Wun Wing Lo) which can result in fuel cross-feeding from one tank to the other if both fuel cocks are on. If they are both pretty full then it can overflow and get into the wing structure.
The remedy is to feed from one tank only in our case.
Mike