For those of you running down-draft webber or dellorto carbs, I just found this very handy tip from the alfa 33 forum.......it just so happens that my 1.7 alf a boxer on twin 40 dellortos is running very rich and makes the air stink of fuel......no surprise last summer it drank fuel like an ocean cruser:



"Black smoke is usually over rich mixture probably due to the floats becoming saturated with fuel (if they are Dellorto carbs, with Webers it would be a leak in the brass float letting in fuel). It could also be a worn float needle assembly or grit under the seat. The idle would have a heavy slow beat to it's rhythm. Aheavy float will result in too high a fuel level in the floatbowl and this can be quickly checked by removing the air filter and looking down the rear barrels of the carbs with the engine running. If there is any fuel dripping fom the auxilary venturi( the small tube in the middle) then that is the area of problem."

just bought a pair of these from a US based ebayer, £15 delivered for the pair!.........interesting info about feed pressure too, aparrently its supposed to be 0.185-0.2Bar (2.6psi) so thats another check to ensure I'm not blasting open the float needle with too much pressure.