if you are sure that coolant channel is blocked. you have my posts and pics on forum ai had that problem, but it is easy to check. between carb and inlet pull off that coolant pipe and see is the coolant flowing from inlet. http://www.shex.max.net.ba/carb/Video184.mp4 - blocked http://www.shex.max.net.ba/carb/Video185.mp4 - flowing
if the air temperature is more than 20 degrees and if it dry, o ring has nothing with perfomanse than. really, tose problems are when it is rain or winter or cold days, than perfomanse goes down more than 50%. and fuel consumption is about doubled. and if you have realy big problems with i ring like i had, consumption was around 16 to 20 litres /100km. a letter on around 9 to 11 litres / 100 km. bad really.
I can only partly agree with your statement here (Shexuel). Yes, the majority of the problems caused by a blocked coolant channel are to do with the cold-start system. Edit: And may not be noticeable once the car is up to temperature. But, if the autochoke housing doesn't (ever) warm up enough to make the choke flap go vertical, or the waxstat doesn't warm up enough to release its influence on the primary throttle, then you'll be burning extra petrol, and running too rich, and (possibly) idling too fast, all the time, n'est ce pas? Ah, as I'm editing this for clarity (?), I see you've added a reply with your 'work-around' detailed, fair enough.
sorry i forgot when i had those problems i refitted flap few mm and waxstat cam and did not have problems even with blocked o ring.
