I have been restoring engines in size from small to large, the older bronze carbs are slightly easier as can heat parts but the die-cast monkey metal ones can be very delicate and more care is needed to get stubborn screws and jets out, many years ago just by accident after washing my hands left a real badly petrol varnish encrusted carburettor in the washing bowl full of hot soapy water, just thinking it might help clean some of the rubbish off the outside. Well it made a tremendous difference most of the brown varnish like deposits left by the petrol had gone whitish and blew away with the air line, even some of the jets just unscrewed easily, so out with a saucepan added a table spoon of washing powder and boiled it for several minutes and left it soaking overnight it was like magic, even managed to clear those very very small cross drillings into the Venturi that some small product carbs have, I had one carburettor brought to me looking like new but wouldn’t idle, I just guessed a long drilling might be blocked, bit of WD 40 or washing up liquid over one end and bit of air in the other and no bubbles and boiling it worked as so easy. Now a word of warning, a DO NOT DO and many people would have said and seen this coming, I would often put a float into hot water to find pin-hole leaks as hot air expands, solder up hole, if it hadn’t got one its important to drill a very small hole and let the float cool and then solder that up and check again. This particular time water must have been near to boiling and just dropped it in and poked it under, I had not checked carefully enough as must have had some bit of petrol in and a minutest hole as instantly it went off pop and took some time teasing it back into shape. Just recently started to rebuild a very early Zenith as jets were so badly damaged had to mill part of them away and make new with screw cut threads as a odd (French?)pitch, one blanking plug had less than three threads. As for good idling I like Zenith and fit those, and can still can get some new, like the 24 T that fitted tractors, Villiers and Petters even the little J.A.P water pumps we still have two in use from the 40s and replaced the old carbs with new 40 odd years ago 13 T CA-2 identical but now I find the petrol pipes are push on. Meetings in London still had parts for the J.A.P and Villiers.
