You can smell petrol when you park up

• this can be a leaking float chamber gasket, fit a new one
• leaking SU carb jet, buy a kit
• flooding float chamber, needle dirty, buy an inline filter
• the pipe from the petrol tanks has rusted away, check it all along its length. (a quick fix is to cut away the bad section and replace it with a gas hose, but this is NOT a permanent fix!)
• if you have just filled the tank, it may be fuel that has expanded out of the fuel tank breather because petrol is cold in the underground filling station tank and it expands in your fuel tank on a hot day.
• seal on the filler cap is worn out
• the pipe to the carb is leaking, very common this as it is always being pulled on and off, fit a new pipe.
• seal in the base of the float chamber on the flexible jet plastic pipe leaking, buy a kit of use an 'A' series engine valve stem seal.
• vaccuum advance is full of petrol, clean it out and fit a trap (little cigar shaped thing you threw away ages ago, now you know what it was for) Note that if the advance is full of gas the engine will not have much power.

Engine pinks-

• you need a decoke
• if you use a lot of oil, this will reduce the octane rating of petrol
• lead is low or non-existant in gas nowadays
• Note: Pinking causes the pistons to melt. Retard the ignition to help somewhat.

Poor fuel economy means:

• fuel leaking somewhere
• brakes binding
• soft tires
• worn out engine
• blocked up air filter
• choke not fully returning
• sticking piston in SUs
• burnt out hot spot in the manifold on Zenith carb cars
• blocked up exhaust pipe (Have you backed up into any clay banks lately?)
• split rubber pipe to the carb
• too much retard on the ignition

Running on after switching off:

• low lead content in petrol
• the engine runs hot because the advance of the ignition is too much now compared to that needed for old gasoline formulations.
• it is the incandescant cardon in the combustion chamber that ignited the petrol and a decoke may improve things