In fact, many of the carbs we receive, do not need rebuilding; the problem s lay elsewhere. Screw both the fast-idle screws in until they just touch the fast idle cam. Could my distributor be out of adjustment via the gear drive by one or two teeth? The oil is there to slow the movement of the piston. Then turn it clockwise 2 full turns so it goes up a little bit.
After each adjustment is made, run the engine at about 2, rpm for ten seconds or so to clear the extra fuel which tends to get into the inlet manifold when you are making an adjustment.
Adjusting an SU carburettor
Alternately, having removed the hood bonnetperhaps a large mirror could be solidly mounted and angled to allow a riding mechanic to see the piston height. This got me in the end at about revs idle and a not so horrendous tailpipe noise but plenty of low noise poofs, several a second. Stop wasting time on YouTube and get serious! Great stuff, my friend. The tool is a long L-shaped hexagonal Allen key which goes inside a thick-walled tube.