Started to notice that the exhaust fumes of my car smell strongly of unburnt petrol. This still occurs when the engine is up to running temp and the choke is not being used. Is this simply because the car does not have a catalytic converter? Are there any other symptoms of a rich mixture? Also, regarding mixture adjustment, the Haynes manual mentions some kind of tamper-proof seal on the carburettor; does anyone have any info on how to deal with that? I believe it is a Weber 2V TLDM carburettor.