Spider2, thanks for your offer. When weather permits (bloody awful out there today!) I'd like to take you up on that offer and am happy to drive, unless you want to see the sights of North London?
I'll get a new air filter handy even though the current one may be just fine.
I'll get some photos of the carbs. Tim, are they visually identifiable? When the car was at Omicron much fiddling was done with the idle mixture screws and balancing was carried out. Presumably once off idle and driving along the main jets are in play - are these adjustable and how would you measure the effect of any changes? Is this a rolling road job?
Thanks
Main jets are really not "adjustable". Stick with manufacturers recommendation unless you are seriously tuning then increase by say 5 (but at expense of mpg!!). Main jet comes into its own after around 2500. Before the the "idle" circuit is managing the transition from idle to 3000. Some folk have found increasing the idle jet overcomes a hesitancy in this transition phase (blamed on modern fuel being thinner). I was one who fiddled around in this area and got convinced increasing the idle jet cured (almost) the hesitancy on my 1600. Then I looked at the valve timing and while near spot on it needed a tweak. After that the hesitancy went away and I dropped back to standard idle jets. Obviously if you up the idle jet this will slightly increase consumption. You need to check that the idle jets have not been changed (easy to do) - they should be 47.5. Your engine has non vernier camshafts so timing this will not be as accurate as the earlier vernier cams fitted to the 303 engine.